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llvm / clang / e8264bb9815647b4c6558aeb045c65965cdb26d3 / . / lib / Sema / SemaStmt.cpp
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//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for statements.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/SemaInternal.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTDiagnostic.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/TypeOrdering.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
using namespace clang;
using namespace sema;
StmtResult Sema::ActOnExprStmt(ExprResult FE) {
if (FE.isInvalid())
return StmtError();
FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(),
/*DiscardedValue*/ true);
if (FE.isInvalid())
return StmtError();
// C99 6.8.3p2: The expression in an expression statement is evaluated as a
// void expression for its side effects. Conversion to void allows any
// operand, even incomplete types.
// Same thing in for stmt first clause (when expr) and third clause.
return StmtResult(FE.getAs<Stmt>());
}
StmtResult Sema::ActOnExprStmtError() {
DiscardCleanupsInEvaluationContext();
return StmtError();
}
StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc,
bool HasLeadingEmptyMacro) {
return new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro);
}
StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc,
SourceLocation EndLoc) {
DeclGroupRef DG = dg.get();
// If we have an invalid decl, just return an error.
if (DG.isNull()) return StmtError();
return new (Context) DeclStmt(DG, StartLoc, EndLoc);
}
void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
DeclGroupRef DG = dg.get();
// If we don't have a declaration, or we have an invalid declaration,
// just return.
if (DG.isNull() || !DG.isSingleDecl())
return;
Decl *decl = DG.getSingleDecl();
if (!decl || decl->isInvalidDecl())
return;
// Only variable declarations are permitted.
VarDecl *var = dyn_cast<VarDecl>(decl);
if (!var) {
Diag(decl->getLocation(), diag::err_non_variable_decl_in_for);
decl->setInvalidDecl();
return;
}
// foreach variables are never actually initialized in the way that
// the parser came up with.
var->setInit(nullptr);
// In ARC, we don't need to retain the iteration variable of a fast
// enumeration loop. Rather than actually trying to catch that
// during declaration processing, we remove the consequences here.
if (getLangOpts().ObjCAutoRefCount) {
QualType type = var->getType();
// Only do this if we inferred the lifetime. Inferred lifetime
// will show up as a local qualifier because explicit lifetime
// should have shown up as an AttributedType instead.
if (type.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong) {
// Add 'const' and mark the variable as pseudo-strong.
var->setType(type.withConst());
var->setARCPseudoStrong(true);
}
}
}
/// \brief Diagnose unused comparisons, both builtin and overloaded operators.
/// For '==' and '!=', suggest fixits for '=' or '|='.
///
/// Adding a cast to void (or other expression wrappers) will prevent the
/// warning from firing.
static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) {
SourceLocation Loc;
bool CanAssign;
enum { Equality, Inequality, Relational, ThreeWay } Kind;
if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
if (!Op->isComparisonOp())
return false;
if (Op->getOpcode() == BO_EQ)
Kind = Equality;
else if (Op->getOpcode() == BO_NE)
Kind = Inequality;
else if (Op->getOpcode() == BO_Cmp)
Kind = ThreeWay;
else {
assert(Op->isRelationalOp());
Kind = Relational;
}
Loc = Op->getOperatorLoc();
CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
} else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
switch (Op->getOperator()) {
case OO_EqualEqual:
Kind = Equality;
break;
case OO_ExclaimEqual:
Kind = Inequality;
break;
case OO_Less:
case OO_Greater:
case OO_GreaterEqual:
case OO_LessEqual:
Kind = Relational;
break;
case OO_Spaceship:
Kind = ThreeWay;
break;
default:
return false;
}
Loc = Op->getOperatorLoc();
CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
} else {
// Not a typo-prone comparison.
return false;
}
// Suppress warnings when the operator, suspicious as it may be, comes from
// a macro expansion.
if (S.SourceMgr.isMacroBodyExpansion(Loc))
return false;
S.Diag(Loc, diag::warn_unused_comparison)
<< (unsigned)Kind << E->getSourceRange();
// If the LHS is a plausible entity to assign to, provide a fixit hint to
// correct common typos.
if (CanAssign) {
if (Kind == Inequality)
S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
<< FixItHint::CreateReplacement(Loc, "|=");
else if (Kind == Equality)
S.Diag(Loc, diag::note_equality_comparison_to_assign)
<< FixItHint::CreateReplacement(Loc, "=");
}
return true;
}
void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
return DiagnoseUnusedExprResult(Label->getSubStmt());
const Expr *E = dyn_cast_or_null<Expr>(S);
if (!E)
return;
// If we are in an unevaluated expression context, then there can be no unused
// results because the results aren't expected to be used in the first place.
if (isUnevaluatedContext())
return;
SourceLocation ExprLoc = E->IgnoreParenImpCasts()->getExprLoc();
// In most cases, we don't want to warn if the expression is written in a
// macro body, or if the macro comes from a system header. If the offending
// expression is a call to a function with the warn_unused_result attribute,
// we warn no matter the location. Because of the order in which the various
// checks need to happen, we factor out the macro-related test here.
bool ShouldSuppress =
SourceMgr.isMacroBodyExpansion(ExprLoc) ||
SourceMgr.isInSystemMacro(ExprLoc);
const Expr *WarnExpr;
SourceLocation Loc;
SourceRange R1, R2;
if (!E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context))
return;
// If this is a GNU statement expression expanded from a macro, it is probably
// unused because it is a function-like macro that can be used as either an
// expression or statement. Don't warn, because it is almost certainly a
// false positive.
if (isa<StmtExpr>(E) && Loc.isMacroID())
return;
// Check if this is the UNREFERENCED_PARAMETER from the Microsoft headers.
// That macro is frequently used to suppress "unused parameter" warnings,
// but its implementation makes clang's -Wunused-value fire. Prevent this.
if (isa<ParenExpr>(E->IgnoreImpCasts()) && Loc.isMacroID()) {
SourceLocation SpellLoc = Loc;
if (findMacroSpelling(SpellLoc, "UNREFERENCED_PARAMETER"))
return;
}
// Okay, we have an unused result. Depending on what the base expression is,
// we might want to make a more specific diagnostic. Check for one of these
// cases now.
unsigned DiagID = diag::warn_unused_expr;
if (const ExprWithCleanups *Temps = dyn_cast<ExprWithCleanups>(E))
E = Temps->getSubExpr();
if (const CXXBindTemporaryExpr *TempExpr = dyn_cast<CXXBindTemporaryExpr>(E))
E = TempExpr->getSubExpr();
if (DiagnoseUnusedComparison(*this, E))
return;
E = WarnExpr;
if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
if (E->getType()->isVoidType())
return;
// If the callee has attribute pure, const, or warn_unused_result, warn with
// a more specific message to make it clear what is happening. If the call
// is written in a macro body, only warn if it has the warn_unused_result
// attribute.
if (const Decl *FD = CE->getCalleeDecl()) {
if (const Attr *A = isa<FunctionDecl>(FD)
? cast<FunctionDecl>(FD)->getUnusedResultAttr()
: FD->getAttr<WarnUnusedResultAttr>()) {
Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
return;
}
if (ShouldSuppress)
return;
if (FD->hasAttr<PureAttr>()) {
Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
return;
}
if (FD->hasAttr<ConstAttr>()) {
Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
return;
}
}
} else if (ShouldSuppress)
return;
if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) {
Diag(Loc, diag::err_arc_unused_init_message) << R1;
return;
}
const ObjCMethodDecl *MD = ME->getMethodDecl();
if (MD) {
if (const auto *A = MD->getAttr<WarnUnusedResultAttr>()) {
Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
return;
}
}
} else if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
const Expr *Source = POE->getSyntacticForm();
if (isa<ObjCSubscriptRefExpr>(Source))
DiagID = diag::warn_unused_container_subscript_expr;
else
DiagID = diag::warn_unused_property_expr;
} else if (const CXXFunctionalCastExpr *FC
= dyn_cast<CXXFunctionalCastExpr>(E)) {
const Expr *E = FC->getSubExpr();
if (const CXXBindTemporaryExpr *TE = dyn_cast<CXXBindTemporaryExpr>(E))
E = TE->getSubExpr();
if (isa<CXXTemporaryObjectExpr>(E))
return;
if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(E))
if (const CXXRecordDecl *RD = CE->getType()->getAsCXXRecordDecl())
if (!RD->getAttr<WarnUnusedAttr>())
return;
}
// Diagnose "(void*) blah" as a typo for "(void) blah".
else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
QualType T = TI->getType();
// We really do want to use the non-canonical type here.
if (T == Context.VoidPtrTy) {
PointerTypeLoc TL = TI->getTypeLoc().castAs<PointerTypeLoc>();
Diag(Loc, diag::warn_unused_voidptr)
<< FixItHint::CreateRemoval(TL.getStarLoc());
return;
}
}
if (E->isGLValue() && E->getType().isVolatileQualified()) {
Diag(Loc, diag::warn_unused_volatile) << R1 << R2;
return;
}
DiagRuntimeBehavior(Loc, nullptr, PDiag(DiagID) << R1 << R2);
}
void Sema::ActOnStartOfCompoundStmt() {
PushCompoundScope();
}
void Sema::ActOnFinishOfCompoundStmt() {
PopCompoundScope();
}
sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
return getCurFunction()->CompoundScopes.back();
}
StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
ArrayRef<Stmt *> Elts, bool isStmtExpr) {
const unsigned NumElts = Elts.size();
// If we're in C89 mode, check that we don't have any decls after stmts. If
// so, emit an extension diagnostic.
if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
// Note that __extension__ can be around a decl.
unsigned i = 0;
// Skip over all declarations.
for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
/*empty*/;
// We found the end of the list or a statement. Scan for another declstmt.
for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
/*empty*/;
if (i != NumElts) {
Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
Diag(D->getLocation(), diag::ext_mixed_decls_code);
}
}
// Warn about unused expressions in statements.
for (unsigned i = 0; i != NumElts; ++i) {
// Ignore statements that are last in a statement expression.
if (isStmtExpr && i == NumElts - 1)
continue;
DiagnoseUnusedExprResult(Elts[i]);
}
// Check for suspicious empty body (null statement) in `for' and `while'
// statements. Don't do anything for template instantiations, this just adds
// noise.
if (NumElts != 0 && !CurrentInstantiationScope &&
getCurCompoundScope().HasEmptyLoopBodies) {
for (unsigned i = 0; i != NumElts - 1; ++i)
DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]);
}
return CompoundStmt::Create(Context, Elts, L, R);
}
StmtResult
Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
SourceLocation DotDotDotLoc, Expr *RHSVal,
SourceLocation ColonLoc) {
assert(LHSVal && "missing expression in case statement");
if (getCurFunction()->SwitchStack.empty()) {
Diag(CaseLoc, diag::err_case_not_in_switch);
return StmtError();
}
ExprResult LHS =
CorrectDelayedTyposInExpr(LHSVal, [this](class Expr *E) {
if (!getLangOpts().CPlusPlus11)
return VerifyIntegerConstantExpression(E);
if (Expr *CondExpr =
getCurFunction()->SwitchStack.back()->getCond()) {
QualType CondType = CondExpr->getType();
llvm::APSInt TempVal;
return CheckConvertedConstantExpression(E, CondType, TempVal,
CCEK_CaseValue);
}
return ExprError();
});
if (LHS.isInvalid())
return StmtError();
LHSVal = LHS.get();
if (!getLangOpts().CPlusPlus11) {
// C99 6.8.4.2p3: The expression shall be an integer constant.
// However, GCC allows any evaluatable integer expression.
if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent()) {
LHSVal = VerifyIntegerConstantExpression(LHSVal).get();
if (!LHSVal)
return StmtError();
}
// GCC extension: The expression shall be an integer constant.
if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent()) {
RHSVal = VerifyIntegerConstantExpression(RHSVal).get();
// Recover from an error by just forgetting about it.
}
}
LHS = ActOnFinishFullExpr(LHSVal, LHSVal->getExprLoc(), false,
getLangOpts().CPlusPlus11);
if (LHS.isInvalid())
return StmtError();
auto RHS = RHSVal ? ActOnFinishFullExpr(RHSVal, RHSVal->getExprLoc(), false,
getLangOpts().CPlusPlus11)
: ExprResult();
if (RHS.isInvalid())
return StmtError();
CaseStmt *CS = new (Context)
CaseStmt(LHS.get(), RHS.get(), CaseLoc, DotDotDotLoc, ColonLoc);
getCurFunction()->SwitchStack.back()->addSwitchCase(CS);
return CS;
}
/// ActOnCaseStmtBody - This installs a statement as the body of a case.
void Sema::ActOnCaseStmtBody(Stmt *caseStmt, Stmt *SubStmt) {
DiagnoseUnusedExprResult(SubStmt);
CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
CS->setSubStmt(SubStmt);
}
StmtResult
Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
Stmt *SubStmt, Scope *CurScope) {
DiagnoseUnusedExprResult(SubStmt);
if (getCurFunction()->SwitchStack.empty()) {
Diag(DefaultLoc, diag::err_default_not_in_switch);
return SubStmt;
}
DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
getCurFunction()->SwitchStack.back()->addSwitchCase(DS);
return DS;
}
StmtResult
Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
SourceLocation ColonLoc, Stmt *SubStmt) {
// If the label was multiply defined, reject it now.
if (TheDecl->getStmt()) {
Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName();
Diag(TheDecl->getLocation(), diag::note_previous_definition);
return SubStmt;
}
// Otherwise, things are good. Fill in the declaration and return it.
LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt);
TheDecl->setStmt(LS);
if (!TheDecl->isGnuLocal()) {
TheDecl->setLocStart(IdentLoc);
if (!TheDecl->isMSAsmLabel()) {
// Don't update the location of MS ASM labels. These will result in
// a diagnostic, and changing the location here will mess that up.
TheDecl->setLocation(IdentLoc);
}
}
return LS;
}
StmtResult Sema::ActOnAttributedStmt(SourceLocation AttrLoc,
ArrayRef<const Attr*> Attrs,
Stmt *SubStmt) {
// Fill in the declaration and return it.
AttributedStmt *LS = AttributedStmt::Create(Context, AttrLoc, Attrs, SubStmt);
return LS;
}
namespace {
class CommaVisitor : public EvaluatedExprVisitor<CommaVisitor> {
typedef EvaluatedExprVisitor<CommaVisitor> Inherited;
Sema &SemaRef;
public:
CommaVisitor(Sema &SemaRef) : Inherited(SemaRef.Context), SemaRef(SemaRef) {}
void VisitBinaryOperator(BinaryOperator *E) {
if (E->getOpcode() == BO_Comma)
SemaRef.DiagnoseCommaOperator(E->getLHS(), E->getExprLoc());
EvaluatedExprVisitor<CommaVisitor>::VisitBinaryOperator(E);
}
};
}
StmtResult
Sema::ActOnIfStmt(SourceLocation IfLoc, bool IsConstexpr, Stmt *InitStmt,
ConditionResult Cond,
Stmt *thenStmt, SourceLocation ElseLoc,
Stmt *elseStmt) {
if (Cond.isInvalid())
Cond = ConditionResult(
*this, nullptr,
MakeFullExpr(new (Context) OpaqueValueExpr(SourceLocation(),
Context.BoolTy, VK_RValue),
IfLoc),
false);
Expr *CondExpr = Cond.get().second;
if (!Diags.isIgnored(diag::warn_comma_operator,
CondExpr->getExprLoc()))
CommaVisitor(*this).Visit(CondExpr);
if (!elseStmt)
DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), thenStmt,
diag::warn_empty_if_body);
return BuildIfStmt(IfLoc, IsConstexpr, InitStmt, Cond, thenStmt, ElseLoc,
elseStmt);
}
StmtResult Sema::BuildIfStmt(SourceLocation IfLoc, bool IsConstexpr,
Stmt *InitStmt, ConditionResult Cond,
Stmt *thenStmt, SourceLocation ElseLoc,
Stmt *elseStmt) {
if (Cond.isInvalid())
return StmtError();
if (IsConstexpr || isa<ObjCAvailabilityCheckExpr>(Cond.get().second))
getCurFunction()->setHasBranchProtectedScope();
DiagnoseUnusedExprResult(thenStmt);
DiagnoseUnusedExprResult(elseStmt);
return new (Context)
IfStmt(Context, IfLoc, IsConstexpr, InitStmt, Cond.get().first,
Cond.get().second, thenStmt, ElseLoc, elseStmt);
}
namespace {
struct CaseCompareFunctor {
bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
const llvm::APSInt &RHS) {
return LHS.first < RHS;
}
bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
return LHS.first < RHS.first;
}
bool operator()(const llvm::APSInt &LHS,
const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
return LHS < RHS.first;
}
};
}
/// CmpCaseVals - Comparison predicate for sorting case values.
///
static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
if (lhs.first < rhs.first)
return true;
if (lhs.first == rhs.first &&
lhs.second->getCaseLoc().getRawEncoding()
< rhs.second->getCaseLoc().getRawEncoding())
return true;
return false;
}
/// CmpEnumVals - Comparison predicate for sorting enumeration values.
///
static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
{
return lhs.first < rhs.first;
}
/// EqEnumVals - Comparison preficate for uniqing enumeration values.
///
static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
{
return lhs.first == rhs.first;
}
/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
/// potentially integral-promoted expression @p expr.
static QualType GetTypeBeforeIntegralPromotion(const Expr *&E) {
if (const auto *CleanUps = dyn_cast<ExprWithCleanups>(E))
E = CleanUps->getSubExpr();
while (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
if (ImpCast->getCastKind() != CK_IntegralCast) break;
E = ImpCast->getSubExpr();
}
return E->getType();
}
ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) {
class SwitchConvertDiagnoser : public ICEConvertDiagnoser {
Expr *Cond;
public:
SwitchConvertDiagnoser(Expr *Cond)
: ICEConvertDiagnoser(/*AllowScopedEnumerations*/true, false, true),
Cond(Cond) {}
SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
QualType T) override {
return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T;
}
SemaDiagnosticBuilder diagnoseIncomplete(
Sema &S, SourceLocation Loc, QualType T) override {
return S.Diag(Loc, diag::err_switch_incomplete_class_type)
<< T << Cond->getSourceRange();
}
SemaDiagnosticBuilder diagnoseExplicitConv(
Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy;
}
SemaDiagnosticBuilder noteExplicitConv(
Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
<< ConvTy->isEnumeralType() << ConvTy;
}
SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
QualType T) override {
return S.Diag(Loc, diag::err_switch_multiple_conversions) << T;
}
SemaDiagnosticBuilder noteAmbiguous(
Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
<< ConvTy->isEnumeralType() << ConvTy;
}
SemaDiagnosticBuilder diagnoseConversion(
Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
llvm_unreachable("conversion functions are permitted");
}
} SwitchDiagnoser(Cond);
ExprResult CondResult =
PerformContextualImplicitConversion(SwitchLoc, Cond, SwitchDiagnoser);
if (CondResult.isInvalid())
return ExprError();
// C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
return UsualUnaryConversions(CondResult.get());
}
StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
Stmt *InitStmt, ConditionResult Cond) {
if (Cond.isInvalid())
return StmtError();
getCurFunction()->setHasBranchIntoScope();
SwitchStmt *SS = new (Context)
SwitchStmt(Context, InitStmt, Cond.get().first, Cond.get().second);
getCurFunction()->SwitchStack.push_back(SS);
return SS;
}
static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
Val = Val.extOrTrunc(BitWidth);
Val.setIsSigned(IsSigned);
}
/// Check the specified case value is in range for the given unpromoted switch
/// type.
static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val,
unsigned UnpromotedWidth, bool UnpromotedSign) {
// If the case value was signed and negative and the switch expression is
// unsigned, don't bother to warn: this is implementation-defined behavior.
// FIXME: Introduce a second, default-ignored warning for this case?
if (UnpromotedWidth < Val.getBitWidth()) {
llvm::APSInt ConvVal(Val);
AdjustAPSInt(ConvVal, UnpromotedWidth, UnpromotedSign);
AdjustAPSInt(ConvVal, Val.getBitWidth(), Val.isSigned());
// FIXME: Use different diagnostics for overflow in conversion to promoted
// type versus "switch expression cannot have this value". Use proper
// IntRange checking rather than just looking at the unpromoted type here.
if (ConvVal != Val)
S.Diag(Loc, diag::warn_case_value_overflow) << Val.toString(10)
<< ConvVal.toString(10);
}
}
typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
/// Returns true if we should emit a diagnostic about this case expression not
/// being a part of the enum used in the switch controlling expression.
static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
const EnumDecl *ED,
const Expr *CaseExpr,
EnumValsTy::iterator &EI,
EnumValsTy::iterator &EIEnd,
const llvm::APSInt &Val) {
if (!ED->isClosed())
return false;
if (const DeclRefExpr *DRE =
dyn_cast<DeclRefExpr>(CaseExpr->IgnoreParenImpCasts())) {
if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
QualType VarType = VD->getType();
QualType EnumType = S.Context.getTypeDeclType(ED);
if (VD->hasGlobalStorage() && VarType.isConstQualified() &&
S.Context.hasSameUnqualifiedType(EnumType, VarType))
return false;
}
}
if (ED->hasAttr<FlagEnumAttr>())
return !S.IsValueInFlagEnum(ED, Val, false);
while (EI != EIEnd && EI->first < Val)
EI++;
if (EI != EIEnd && EI->first == Val)
return false;
return true;
}
static void checkEnumTypesInSwitchStmt(Sema &S, const Expr *Cond,
const Expr *Case) {
QualType CondType = GetTypeBeforeIntegralPromotion(Cond);
QualType CaseType = Case->getType();
const EnumType *CondEnumType = CondType->getAs<EnumType>();
const EnumType *CaseEnumType = CaseType->getAs<EnumType>();
if (!CondEnumType || !CaseEnumType)
return;
// Ignore anonymous enums.
if (!CondEnumType->getDecl()->getIdentifier() &&
!CondEnumType->getDecl()->getTypedefNameForAnonDecl())
return;
if (!CaseEnumType->getDecl()->getIdentifier() &&
!CaseEnumType->getDecl()->getTypedefNameForAnonDecl())
return;
if (S.Context.hasSameUnqualifiedType(CondType, CaseType))
return;
S.Diag(Case->getExprLoc(), diag::warn_comparison_of_mixed_enum_types_switch)
<< CondType << CaseType << Cond->getSourceRange()
<< Case->getSourceRange();
}
StmtResult
Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
Stmt *BodyStmt) {
SwitchStmt *SS = cast<SwitchStmt>(Switch);
assert(SS == getCurFunction()->SwitchStack.back() &&
"switch stack missing push/pop!");
getCurFunction()->SwitchStack.pop_back();
if (!BodyStmt) return StmtError();
SS->setBody(BodyStmt, SwitchLoc);
Expr *CondExpr = SS->getCond();
if (!CondExpr) return StmtError();
QualType CondType = CondExpr->getType();
const Expr *CondExprBeforePromotion = CondExpr;
QualType CondTypeBeforePromotion =
GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
// C++ 6.4.2.p2:
// Integral promotions are performed (on the switch condition).
//
// A case value unrepresentable by the original switch condition
// type (before the promotion) doesn't make sense, even when it can
// be represented by the promoted type. Therefore we need to find
// the pre-promotion type of the switch condition.
if (!CondExpr->isTypeDependent()) {
// We have already converted the expression to an integral or enumeration
// type, when we started the switch statement. If we don't have an
// appropriate type now, just return an error.
if (!CondType->isIntegralOrEnumerationType())
return StmtError();
if (CondExpr->isKnownToHaveBooleanValue()) {
// switch(bool_expr) {...} is often a programmer error, e.g.
// switch(n && mask) { ... } // Doh - should be "n & mask".
// One can always use an if statement instead of switch(bool_expr).
Diag(SwitchLoc, diag::warn_bool_switch_condition)
<< CondExpr->getSourceRange();
}
}
// Get the bitwidth of the switched-on value after promotions. We must
// convert the integer case values to this width before comparison.
bool HasDependentValue
= CondExpr->isTypeDependent() || CondExpr->isValueDependent();
unsigned CondWidth = HasDependentValue ? 0 : Context.getIntWidth(CondType);
bool CondIsSigned = CondType->isSignedIntegerOrEnumerationType();
// Get the width and signedness that the condition might actually have, for
// warning purposes.
// FIXME: Grab an IntRange for the condition rather than using the unpromoted
// type.
unsigned CondWidthBeforePromotion
= HasDependentValue ? 0 : Context.getIntWidth(CondTypeBeforePromotion);
bool CondIsSignedBeforePromotion
= CondTypeBeforePromotion->isSignedIntegerOrEnumerationType();
// Accumulate all of the case values in a vector so that we can sort them
// and detect duplicates. This vector contains the APInt for the case after
// it has been converted to the condition type.
typedef SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
CaseValsTy CaseVals;
// Keep track of any GNU case ranges we see. The APSInt is the low value.
typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
CaseRangesTy CaseRanges;
DefaultStmt *TheDefaultStmt = nullptr;
bool CaseListIsErroneous = false;
for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
SC = SC->getNextSwitchCase()) {
if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
if (TheDefaultStmt) {
Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
// FIXME: Remove the default statement from the switch block so that
// we'll return a valid AST. This requires recursing down the AST and
// finding it, not something we are set up to do right now. For now,
// just lop the entire switch stmt out of the AST.
CaseListIsErroneous = true;
}
TheDefaultStmt = DS;
} else {
CaseStmt *CS = cast<CaseStmt>(SC);
Expr *Lo = CS->getLHS();
if (Lo->isTypeDependent() || Lo->isValueDependent()) {
HasDependentValue = true;
break;
}
checkEnumTypesInSwitchStmt(*this, CondExpr, Lo);
llvm::APSInt LoVal;
if (getLangOpts().CPlusPlus11) {
// C++11 [stmt.switch]p2: the constant-expression shall be a converted
// constant expression of the promoted type of the switch condition.
ExprResult ConvLo =
CheckConvertedConstantExpression(Lo, CondType, LoVal, CCEK_CaseValue);
if (ConvLo.isInvalid()) {
CaseListIsErroneous = true;
continue;
}
Lo = ConvLo.get();
} else {
// We already verified that the expression has a i-c-e value (C99
// 6.8.4.2p3) - get that value now.
LoVal = Lo->EvaluateKnownConstInt(Context);
// If the LHS is not the same type as the condition, insert an implicit
// cast.
Lo = DefaultLvalueConversion(Lo).get();
Lo = ImpCastExprToType(Lo, CondType, CK_IntegralCast).get();
}
// Check the unconverted value is within the range of possible values of
// the switch expression.
checkCaseValue(*this, Lo->getLocStart(), LoVal,
CondWidthBeforePromotion, CondIsSignedBeforePromotion);
// Convert the value to the same width/sign as the condition.
AdjustAPSInt(LoVal, CondWidth, CondIsSigned);
CS->setLHS(Lo);
// If this is a case range, remember it in CaseRanges, otherwise CaseVals.
if (CS->getRHS()) {
if (CS->getRHS()->isTypeDependent() ||
CS->getRHS()->isValueDependent()) {
HasDependentValue = true;
break;
}
CaseRanges.push_back(std::make_pair(LoVal, CS));
} else
CaseVals.push_back(std::make_pair(LoVal, CS));
}
}
if (!HasDependentValue) {
// If we don't have a default statement, check whether the
// condition is constant.
llvm::APSInt ConstantCondValue;
bool HasConstantCond = false;
if (!HasDependentValue && !TheDefaultStmt) {
HasConstantCond = CondExpr->EvaluateAsInt(ConstantCondValue, Context,
Expr::SE_AllowSideEffects);
assert(!HasConstantCond ||
(ConstantCondValue.getBitWidth() == CondWidth &&
ConstantCondValue.isSigned() == CondIsSigned));
}
bool ShouldCheckConstantCond = HasConstantCond;
// Sort all the scalar case values so we can easily detect duplicates.
std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
if (!CaseVals.empty()) {
for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
if (ShouldCheckConstantCond &&
CaseVals[i].first == ConstantCondValue)
ShouldCheckConstantCond = false;
if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
// If we have a duplicate, report it.
// First, determine if either case value has a name
StringRef PrevString, CurrString;
Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts();
Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts();
if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(PrevCase)) {
PrevString = DeclRef->getDecl()->getName();
}
if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(CurrCase)) {
CurrString = DeclRef->getDecl()->getName();
}
SmallString<16> CaseValStr;
CaseVals[i-1].first.toString(CaseValStr);
if (PrevString == CurrString)
Diag(CaseVals[i].second->getLHS()->getLocStart(),
diag::err_duplicate_case) <<
(PrevString.empty() ? StringRef(CaseValStr) : PrevString);
else
Diag(CaseVals[i].second->getLHS()->getLocStart(),
diag::err_duplicate_case_differing_expr) <<
(PrevString.empty() ? StringRef(CaseValStr) : PrevString) <<
(CurrString.empty() ? StringRef(CaseValStr) : CurrString) <<
CaseValStr;
Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
diag::note_duplicate_case_prev);
// FIXME: We really want to remove the bogus case stmt from the
// substmt, but we have no way to do this right now.
CaseListIsErroneous = true;
}
}
}
// Detect duplicate case ranges, which usually don't exist at all in
// the first place.
if (!CaseRanges.empty()) {
// Sort all the case ranges by their low value so we can easily detect
// overlaps between ranges.
std::stable_sort(CaseRanges.begin(), CaseRanges.end());
// Scan the ranges, computing the high values and removing empty ranges.
std::vector<llvm::APSInt> HiVals;
for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
llvm::APSInt &LoVal = CaseRanges[i].first;
CaseStmt *CR = CaseRanges[i].second;
Expr *Hi = CR->getRHS();
llvm::APSInt HiVal;
if (getLangOpts().CPlusPlus11) {
// C++11 [stmt.switch]p2: the constant-expression shall be a converted
// constant expression of the promoted type of the switch condition.
ExprResult ConvHi =
CheckConvertedConstantExpression(Hi, CondType, HiVal,
CCEK_CaseValue);
if (ConvHi.isInvalid()) {
CaseListIsErroneous = true;
continue;
}
Hi = ConvHi.get();
} else {
HiVal = Hi->EvaluateKnownConstInt(Context);
// If the RHS is not the same type as the condition, insert an
// implicit cast.
Hi = DefaultLvalueConversion(Hi).get();
Hi = ImpCastExprToType(Hi, CondType, CK_IntegralCast).get();
}
// Check the unconverted value is within the range of possible values of
// the switch expression.
checkCaseValue(*this, Hi->getLocStart(), HiVal,
CondWidthBeforePromotion, CondIsSignedBeforePromotion);
// Convert the value to the same width/sign as the condition.
AdjustAPSInt(HiVal, CondWidth, CondIsSigned);
CR->setRHS(Hi);
// If the low value is bigger than the high value, the case is empty.
if (LoVal > HiVal) {
Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
<< SourceRange(CR->getLHS()->getLocStart(),
Hi->getLocEnd());
CaseRanges.erase(CaseRanges.begin()+i);
--i;
--e;
continue;
}
if (ShouldCheckConstantCond &&
LoVal <= ConstantCondValue &&
ConstantCondValue <= HiVal)
ShouldCheckConstantCond = false;
HiVals.push_back(HiVal);
}
// Rescan the ranges, looking for overlap with singleton values and other
// ranges. Since the range list is sorted, we only need to compare case
// ranges with their neighbors.
for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
llvm::APSInt &CRLo = CaseRanges[i].first;
llvm::APSInt &CRHi = HiVals[i];
CaseStmt *CR = CaseRanges[i].second;
// Check to see whether the case range overlaps with any
// singleton cases.
CaseStmt *OverlapStmt = nullptr;
llvm::APSInt OverlapVal(32);
// Find the smallest value >= the lower bound. If I is in the
// case range, then we have overlap.
CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
CaseVals.end(), CRLo,
CaseCompareFunctor());
if (I != CaseVals.end() && I->first < CRHi) {
OverlapVal = I->first; // Found overlap with scalar.
OverlapStmt = I->second;
}
// Find the smallest value bigger than the upper bound.
I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
OverlapVal = (I-1)->first; // Found overlap with scalar.
OverlapStmt = (I-1)->second;
}
// Check to see if this case stmt overlaps with the subsequent
// case range.
if (i && CRLo <= HiVals[i-1]) {
OverlapVal = HiVals[i-1]; // Found overlap with range.
OverlapStmt = CaseRanges[i-1].second;
}
if (OverlapStmt) {
// If we have a duplicate, report it.
Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
<< OverlapVal.toString(10);
Diag(OverlapStmt->getLHS()->getLocStart(),
diag::note_duplicate_case_prev);
// FIXME: We really want to remove the bogus case stmt from the
// substmt, but we have no way to do this right now.
CaseListIsErroneous = true;
}
}
}
// Complain if we have a constant condition and we didn't find a match.
if (!CaseListIsErroneous && ShouldCheckConstantCond) {
// TODO: it would be nice if we printed enums as enums, chars as
// chars, etc.
Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
<< ConstantCondValue.toString(10)
<< CondExpr->getSourceRange();
}
// Check to see if switch is over an Enum and handles all of its
// values. We only issue a warning if there is not 'default:', but
// we still do the analysis to preserve this information in the AST
// (which can be used by flow-based analyes).
//
const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
// If switch has default case, then ignore it.
if (!CaseListIsErroneous && !HasConstantCond && ET &&
ET->getDecl()->isCompleteDefinition()) {
const EnumDecl *ED = ET->getDecl();
EnumValsTy EnumVals;
// Gather all enum values, set their type and sort them,
// allowing easier comparison with CaseVals.
for (auto *EDI : ED->enumerators()) {
llvm::APSInt Val = EDI->getInitVal();
AdjustAPSInt(Val, CondWidth, CondIsSigned);
EnumVals.push_back(std::make_pair(Val, EDI));
}
std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
auto EI = EnumVals.begin(), EIEnd =
std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
// See which case values aren't in enum.
for (CaseValsTy::const_iterator CI = CaseVals.begin();
CI != CaseVals.end(); CI++) {
Expr *CaseExpr = CI->second->getLHS();
if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
CI->first))
Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
<< CondTypeBeforePromotion;
}
// See which of case ranges aren't in enum
EI = EnumVals.begin();
for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
RI != CaseRanges.end(); RI++) {
Expr *CaseExpr = RI->second->getLHS();
if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
RI->first))
Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
<< CondTypeBeforePromotion;
llvm::APSInt Hi =
RI->second->getRHS()->EvaluateKnownConstInt(Context);
AdjustAPSInt(Hi, CondWidth, CondIsSigned);
CaseExpr = RI->second->getRHS();
if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
Hi))
Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
<< CondTypeBeforePromotion;
}
// Check which enum vals aren't in switch
auto CI = CaseVals.begin();
auto RI = CaseRanges.begin();
bool hasCasesNotInSwitch = false;
SmallVector<DeclarationName,8> UnhandledNames;
for (EI = EnumVals.begin(); EI != EIEnd; EI++){
// Drop unneeded case values
while (CI != CaseVals.end() && CI->first < EI->first)
CI++;
if (CI != CaseVals.end() && CI->first == EI->first)
continue;
// Drop unneeded case ranges
for (; RI != CaseRanges.end(); RI++) {
llvm::APSInt Hi =
RI->second->getRHS()->EvaluateKnownConstInt(Context);
AdjustAPSInt(Hi, CondWidth, CondIsSigned);
if (EI->first <= Hi)
break;
}
if (RI == CaseRanges.end() || EI->first < RI->first) {
hasCasesNotInSwitch = true;
UnhandledNames.push_back(EI->second->getDeclName());
}
}
if (TheDefaultStmt && UnhandledNames.empty() && ED->isClosedNonFlag())
Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
// Produce a nice diagnostic if multiple values aren't handled.
if (!UnhandledNames.empty()) {
DiagnosticBuilder DB = Diag(CondExpr->getExprLoc(),
TheDefaultStmt ? diag::warn_def_missing_case
: diag::warn_missing_case)
<< (int)UnhandledNames.size();
for (size_t I = 0, E = std::min(UnhandledNames.size(), (size_t)3);
I != E; ++I)
DB << UnhandledNames[I];
}
if (!hasCasesNotInSwitch)
SS->setAllEnumCasesCovered();
}
}
if (BodyStmt)
DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), BodyStmt,
diag::warn_empty_switch_body);
// FIXME: If the case list was broken is some way, we don't have a good system
// to patch it up. Instead, just return the whole substmt as broken.
if (CaseListIsErroneous)
return StmtError();
return SS;
}
void
Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
Expr *SrcExpr) {
if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc()))
return;
if (const EnumType *ET = DstType->getAs<EnumType>())
if (!Context.hasSameUnqualifiedType(SrcType, DstType) &&
SrcType->isIntegerType()) {
if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
SrcExpr->isIntegerConstantExpr(Context)) {
// Get the bitwidth of the enum value before promotions.
unsigned DstWidth = Context.getIntWidth(DstType);
bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
AdjustAPSInt(RhsVal, DstWidth, DstIsSigned);
const EnumDecl *ED = ET->getDecl();
if (!ED->isClosed())
return;
if (ED->hasAttr<FlagEnumAttr>()) {
if (!IsValueInFlagEnum(ED, RhsVal, true))
Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
<< DstType.getUnqualifiedType();
} else {
typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl *>, 64>
EnumValsTy;
EnumValsTy EnumVals;
// Gather all enum values, set their type and sort them,
// allowing easier comparison with rhs constant.
for (auto *EDI : ED->enumerators()) {
llvm::APSInt Val = EDI->getInitVal();
AdjustAPSInt(Val, DstWidth, DstIsSigned);
EnumVals.push_back(std::make_pair(Val, EDI));
}
if (EnumVals.empty())
return;
std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
EnumValsTy::iterator EIend =
std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
// See which values aren't in the enum.
EnumValsTy::const_iterator EI = EnumVals.begin();
while (EI != EIend && EI->first < RhsVal)
EI++;
if (EI == EIend || EI->first != RhsVal) {
Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
<< DstType.getUnqualifiedType();
}
}
}
}
}
StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc, ConditionResult Cond,
Stmt *Body) {
if (Cond.isInvalid())
return StmtError();
auto CondVal = Cond.get();
CheckBreakContinueBinding(CondVal.second);
if (CondVal.second &&
!Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc()))
CommaVisitor(*this).Visit(CondVal.second);
DiagnoseUnusedExprResult(Body);
if (isa<NullStmt>(Body))
getCurCompoundScope().setHasEmptyLoopBodies();
return new (Context)
WhileStmt(Context, CondVal.first, CondVal.second, Body, WhileLoc);
}
StmtResult
Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
SourceLocation WhileLoc, SourceLocation CondLParen,
Expr *Cond, SourceLocation CondRParen) {
assert(Cond && "ActOnDoStmt(): missing expression");
CheckBreakContinueBinding(Cond);
ExprResult CondResult = CheckBooleanCondition(DoLoc, Cond);
if (CondResult.isInvalid())
return StmtError();
Cond = CondResult.get();
CondResult = ActOnFinishFullExpr(Cond, DoLoc);
if (CondResult.isInvalid())
return StmtError();
Cond = CondResult.get();
DiagnoseUnusedExprResult(Body);
return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen);
}
namespace {
// Use SetVector since the diagnostic cares about the ordering of the Decl's.
using DeclSetVector =
llvm::SetVector<VarDecl *, llvm::SmallVector<VarDecl *, 8>,
llvm::SmallPtrSet<VarDecl *, 8>>;
// This visitor will traverse a conditional statement and store all
// the evaluated decls into a vector. Simple is set to true if none
// of the excluded constructs are used.
class DeclExtractor : public EvaluatedExprVisitor<DeclExtractor> {
DeclSetVector &Decls;
SmallVectorImpl<SourceRange> &Ranges;
bool Simple;
public:
typedef EvaluatedExprVisitor<DeclExtractor> Inherited;
DeclExtractor(Sema &S, DeclSetVector &Decls,
SmallVectorImpl<SourceRange> &Ranges) :
Inherited(S.Context),
Decls(Decls),
Ranges(Ranges),
Simple(true) {}
bool isSimple() { return Simple; }
// Replaces the method in EvaluatedExprVisitor.
void VisitMemberExpr(MemberExpr* E) {
Simple = false;
}
// Any Stmt not whitelisted will cause the condition to be marked complex.
void VisitStmt(Stmt *S) {
Simple = false;
}
void VisitBinaryOperator(BinaryOperator *E) {
Visit(E->getLHS());
Visit(E->getRHS());
}
void VisitCastExpr(CastExpr *E) {
Visit(E->getSubExpr());
}
void VisitUnaryOperator(UnaryOperator *E) {
// Skip checking conditionals with derefernces.
if (E->getOpcode() == UO_Deref)
Simple = false;
else
Visit(E->getSubExpr());
}
void VisitConditionalOperator(ConditionalOperator *E) {
Visit(E->getCond());
Visit(E->getTrueExpr());
Visit(E->getFalseExpr());
}
void VisitParenExpr(ParenExpr *E) {
Visit(E->getSubExpr());
}
void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
Visit(E->getOpaqueValue()->getSourceExpr());
Visit(E->getFalseExpr());
}
void VisitIntegerLiteral(IntegerLiteral *E) { }
void VisitFloatingLiteral(FloatingLiteral *E) { }
void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { }
void VisitCharacterLiteral(CharacterLiteral *E) { }
void VisitGNUNullExpr(GNUNullExpr *E) { }
void VisitImaginaryLiteral(ImaginaryLiteral *E) { }
void VisitDeclRefExpr(DeclRefExpr *E) {
VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
if (!VD) return;
Ranges.push_back(E->getSourceRange());
Decls.insert(VD);
}
}; // end class DeclExtractor
// DeclMatcher checks to see if the decls are used in a non-evaluated
// context.
class DeclMatcher : public EvaluatedExprVisitor<DeclMatcher> {
DeclSetVector &Decls;
bool FoundDecl;
public:
typedef EvaluatedExprVisitor<DeclMatcher> Inherited;
DeclMatcher(Sema &S, DeclSetVector &Decls, Stmt *Statement) :
Inherited(S.Context), Decls(Decls), FoundDecl(false) {
if (!Statement) return;
Visit(Statement);
}
void VisitReturnStmt(ReturnStmt *S) {
FoundDecl = true;
}
void VisitBreakStmt(BreakStmt *S) {
FoundDecl = true;
}
void VisitGotoStmt(GotoStmt *S) {
FoundDecl = true;
}
void VisitCastExpr(CastExpr *E) {
if (E->getCastKind() == CK_LValueToRValue)
CheckLValueToRValueCast(E->getSubExpr());
else
Visit(E->getSubExpr());
}
void CheckLValueToRValueCast(Expr *E) {
E = E->IgnoreParenImpCasts();
if (isa<DeclRefExpr>(E)) {
return;
}
if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
Visit(CO->getCond());
CheckLValueToRValueCast(CO->getTrueExpr());
CheckLValueToRValueCast(CO->getFalseExpr());
return;
}
if (BinaryConditionalOperator *BCO =
dyn_cast<BinaryConditionalOperator>(E)) {
CheckLValueToRValueCast(BCO->getOpaqueValue()->getSourceExpr());
CheckLValueToRValueCast(BCO->getFalseExpr());
return;
}
Visit(E);
}
void VisitDeclRefExpr(DeclRefExpr *E) {
if (VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
if (Decls.count(VD))
FoundDecl = true;
}
void VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
// Only need to visit the semantics for POE.
// SyntaticForm doesn't really use the Decal.
for (auto *S : POE->semantics()) {
if (auto *OVE = dyn_cast<OpaqueValueExpr>(S))
// Look past the OVE into the expression it binds.
Visit(OVE->getSourceExpr());
else
Visit(S);
}
}
bool FoundDeclInUse() { return FoundDecl; }
}; // end class DeclMatcher
void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
Expr *Third, Stmt *Body) {
// Condition is empty
if (!Second) return;
if (S.Diags.isIgnored(diag::warn_variables_not_in_loop_body,
Second->getLocStart()))
return;
PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body);
DeclSetVector Decls;
SmallVector<SourceRange, 10> Ranges;
DeclExtractor DE(S, Decls, Ranges);
DE.Visit(Second);
// Don't analyze complex conditionals.
if (!DE.isSimple()) return;
// No decls found.
if (Decls.size() == 0) return;
// Don't warn on volatile, static, or global variables.
for (auto *VD : Decls)
if (VD->getType().isVolatileQualified() || VD->hasGlobalStorage())
return;
if (DeclMatcher(S, Decls, Second).FoundDeclInUse() ||
DeclMatcher(S, Decls, Third).FoundDeclInUse() ||
DeclMatcher(S, Decls, Body).FoundDeclInUse())
return;
// Load decl names into diagnostic.
if (Decls.size() > 4) {
PDiag << 0;
} else {
PDiag << (unsigned)Decls.size();
for (auto *VD : Decls)
PDiag << VD->getDeclName();
}
for (auto Range : Ranges)
PDiag << Range;
S.Diag(Ranges.begin()->getBegin(), PDiag);
}
// If Statement is an incemement or decrement, return true and sets the
// variables Increment and DRE.
bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment,
DeclRefExpr *&DRE) {
if (auto Cleanups = dyn_cast<ExprWithCleanups>(Statement))
if (!Cleanups->cleanupsHaveSideEffects())
Statement = Cleanups->getSubExpr();
if (UnaryOperator *UO = dyn_cast<UnaryOperator>(Statement)) {
switch (UO->getOpcode()) {
default: return false;
case UO_PostInc:
case UO_PreInc:
Increment = true;
break;
case UO_PostDec:
case UO_PreDec:
Increment = false;
break;
}
DRE = dyn_cast<DeclRefExpr>(UO->getSubExpr());
return DRE;
}
if (CXXOperatorCallExpr *Call = dyn_cast<CXXOperatorCallExpr>(Statement)) {
FunctionDecl *FD = Call->getDirectCallee();
if (!FD || !FD->isOverloadedOperator()) return false;
switch (FD->getOverloadedOperator()) {
default: return false;
case OO_PlusPlus:
Increment = true;
break;
case OO_MinusMinus:
Increment = false;
break;
}
DRE = dyn_cast<DeclRefExpr>(Call->getArg(0));
return DRE;
}
return false;
}
// A visitor to determine if a continue or break statement is a
// subexpression.
class BreakContinueFinder : public ConstEvaluatedExprVisitor<BreakContinueFinder> {
SourceLocation BreakLoc;
SourceLocation ContinueLoc;
bool InSwitch = false;
public:
BreakContinueFinder(Sema &S, const Stmt* Body) :
Inherited(S.Context) {
Visit(Body);
}
typedef ConstEvaluatedExprVisitor<BreakContinueFinder> Inherited;
void VisitContinueStmt(const ContinueStmt* E) {
ContinueLoc = E->getContinueLoc();
}
void VisitBreakStmt(const BreakStmt* E) {
if (!InSwitch)
BreakLoc = E->getBreakLoc();
}
void VisitSwitchStmt(const SwitchStmt* S) {
if (const Stmt *Init = S->getInit())
Visit(Init);
if (const Stmt *CondVar = S->getConditionVariableDeclStmt())
Visit(CondVar);
if (const Stmt *Cond = S->getCond())
Visit(Cond);
// Don't return break statements from the body of a switch.
InSwitch = true;
if (const Stmt *Body = S->getBody())
Visit(Body);
InSwitch = false;
}
void VisitForStmt(const ForStmt *S) {
// Only visit the init statement of a for loop; the body
// has a different break/continue scope.
if (const Stmt *Init = S->getInit())
Visit(Init);
}
void VisitWhileStmt(const WhileStmt *) {
// Do nothing; the children of a while loop have a different
// break/continue scope.
}
void VisitDoStmt(const DoStmt *) {
// Do nothing; the children of a while loop have a different
// break/continue scope.
}
void VisitCXXForRangeStmt(const CXXForRangeStmt *S) {
// Only visit the initialization of a for loop; the body
// has a different break/continue scope.
if (const Stmt *Range = S->getRangeStmt())
Visit(Range);
if (const Stmt *Begin = S->getBeginStmt())
Visit(Begin);
if (const Stmt *End = S->getEndStmt())
Visit(End);
}
void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S) {
// Only visit the initialization of a for loop; the body
// has a different break/continue scope.
if (const Stmt *Element = S->getElement())
Visit(Element);
if (const Stmt *Collection = S->getCollection())
Visit(Collection);
}
bool ContinueFound() { return ContinueLoc.isValid(); }
bool BreakFound() { return BreakLoc.isValid(); }
SourceLocation GetContinueLoc() { return ContinueLoc; }
SourceLocation GetBreakLoc() { return BreakLoc; }
}; // end class BreakContinueFinder
// Emit a warning when a loop increment/decrement appears twice per loop
// iteration. The conditions which trigger this warning are:
// 1) The last statement in the loop body and the third expression in the
// for loop are both increment or both decrement of the same variable
// 2) No continue statements in the loop body.
void CheckForRedundantIteration(Sema &S, Expr *Third, Stmt *Body) {
// Return when there is nothing to check.
if (!Body || !Third) return;
if (S.Diags.isIgnored(diag::warn_redundant_loop_iteration,
Third->getLocStart()))
return;
// Get the last statement from the loop body.
CompoundStmt *CS = dyn_cast<CompoundStmt>(Body);
if (!CS || CS->body_empty()) return;
Stmt *LastStmt = CS->body_back();
if (!LastStmt) return;
bool LoopIncrement, LastIncrement;
DeclRefExpr *LoopDRE, *LastDRE;
if (!ProcessIterationStmt(S, Third, LoopIncrement, LoopDRE)) return;
if (!ProcessIterationStmt(S, LastStmt, LastIncrement, LastDRE)) return;
// Check that the two statements are both increments or both decrements
// on the same variable.
if (LoopIncrement != LastIncrement ||
LoopDRE->getDecl() != LastDRE->getDecl()) return;
if (BreakContinueFinder(S, Body).ContinueFound()) return;
S.Diag(LastDRE->getLocation(), diag::warn_redundant_loop_iteration)
<< LastDRE->getDecl() << LastIncrement;
S.Diag(LoopDRE->getLocation(), diag::note_loop_iteration_here)
<< LoopIncrement;
}
} // end namespace
void Sema::CheckBreakContinueBinding(Expr *E) {
if (!E || getLangOpts().CPlusPlus)
return;
BreakContinueFinder BCFinder(*this, E);
Scope *BreakParent = CurScope->getBreakParent();
if (BCFinder.BreakFound() && BreakParent) {
if (BreakParent->getFlags() & Scope::SwitchScope) {
Diag(BCFinder.GetBreakLoc(), diag::warn_break_binds_to_switch);
} else {
Diag(BCFinder.GetBreakLoc(), diag::warn_loop_ctrl_binds_to_inner)
<< "break";
}
} else if (BCFinder.ContinueFound() && CurScope->getContinueParent()) {
Diag(BCFinder.GetContinueLoc(), diag::warn_loop_ctrl_binds_to_inner)
<< "continue";
}
}
StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
Stmt *First, ConditionResult Second,
FullExprArg third, SourceLocation RParenLoc,
Stmt *Body) {
if (Second.isInvalid())
return StmtError();
if (!getLangOpts().CPlusPlus) {
if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
// C99 6.8.5p3: The declaration part of a 'for' statement shall only
// declare identifiers for objects having storage class 'auto' or
// 'register'.
for (auto *DI : DS->decls()) {
VarDecl *VD = dyn_cast<VarDecl>(DI);
if (VD && VD->isLocalVarDecl() && !VD->hasLocalStorage())
VD = nullptr;
if (!VD) {
Diag(DI->getLocation(), diag::err_non_local_variable_decl_in_for);
DI->setInvalidDecl();
}
}
}
}
CheckBreakContinueBinding(Second.get().second);
CheckBreakContinueBinding(third.get());
if (!Second.get().first)
CheckForLoopConditionalStatement(*this, Second.get().second, third.get(),
Body);
CheckForRedundantIteration(*this, third.get(), Body);
if (Second.get().second &&
!Diags.isIgnored(diag::warn_comma_operator,
Second.get().second->getExprLoc()))
CommaVisitor(*this).Visit(Second.get().second);
Expr *Third = third.release().getAs<Expr>();
DiagnoseUnusedExprResult(First);
DiagnoseUnusedExprResult(Third);
DiagnoseUnusedExprResult(Body);
if (isa<NullStmt>(Body))
getCurCompoundScope().setHasEmptyLoopBodies();
return new (Context)
ForStmt(Context, First, Second.get().second, Second.get().first, Third,
Body, ForLoc, LParenLoc, RParenLoc);
}
/// In an Objective C collection iteration statement:
/// for (x in y)
/// x can be an arbitrary l-value expression. Bind it up as a
/// full-expression.
StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
// Reduce placeholder expressions here. Note that this rejects the
// use of pseudo-object l-values in this position.
ExprResult result = CheckPlaceholderExpr(E);
if (result.isInvalid()) return StmtError();
E = result.get();
ExprResult FullExpr = ActOnFinishFullExpr(E);
if (FullExpr.isInvalid())
return StmtError();
return StmtResult(static_cast<Stmt*>(FullExpr.get()));
}
ExprResult
Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) {
if (!collection)
return ExprError();
ExprResult result = CorrectDelayedTyposInExpr(collection);
if (!result.isUsable())
return ExprError();
collection = result.get();
// Bail out early if we've got a type-dependent expression.
if (collection->isTypeDependent()) return collection;
// Perform normal l-value conversion.
result = DefaultFunctionArrayLvalueConversion(collection);
if (result.isInvalid())
return ExprError();
collection = result.get();
// The operand needs to have object-pointer type.
// TODO: should we do a contextual conversion?
const ObjCObjectPointerType *pointerType =
collection->getType()->getAs<ObjCObjectPointerType>();
if (!pointerType)
return Diag(forLoc, diag::err_collection_expr_type)
<< collection->getType() << collection->getSourceRange();
// Check that the operand provides
// - countByEnumeratingWithState:objects:count:
const ObjCObjectType *objectType = pointerType->getObjectType();
ObjCInterfaceDecl *iface = objectType->getInterface();
// If we have a forward-declared type, we can't do this check.
// Under ARC, it is an error not to have a forward-declared class.
if (iface &&
(getLangOpts().ObjCAutoRefCount
? RequireCompleteType(forLoc, QualType(objectType, 0),
diag::err_arc_collection_forward, collection)
: !isCompleteType(forLoc, QualType(objectType, 0)))) {
// Otherwise, if we have any useful type information, check that
// the type declares the appropriate method.
} else if (iface || !objectType->qual_empty()) {
IdentifierInfo *selectorIdents[] = {
&Context.Idents.get("countByEnumeratingWithState"),
&Context.Idents.get("objects"),
&Context.Idents.get("count")
};
Selector selector = Context.Selectors.getSelector(3, &selectorIdents[0]);
ObjCMethodDecl *method = nullptr;
// If there's an interface, look in both the public and private APIs.
if (iface) {
method = iface->lookupInstanceMethod(selector);
if (!method) method = iface->lookupPrivateMethod(selector);
}
// Also check protocol qualifiers.
if (!method)
method = LookupMethodInQualifiedType(selector, pointerType,
/*instance*/ true);
// If we didn't find it anywhere, give up.
if (!method) {
Diag(forLoc, diag::warn_collection_expr_type)
<< collection->getType() << selector << collection->getSourceRange();
}
// TODO: check for an incompatible signature?
}
// Wrap up any cleanups in the expression.
return collection;
}
StmtResult
Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
Stmt *First, Expr *collection,
SourceLocation RParenLoc) {
getCurFunction()->setHasBranchProtectedScope();
ExprResult CollectionExprResult =
CheckObjCForCollectionOperand(ForLoc, collection);
if (First) {
QualType FirstType;
if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
if (!DS->isSingleDecl())
return StmtError(Diag((*DS->decl_begin())->getLocation(),
diag::err_toomany_element_decls));
VarDecl *D = dyn_cast<VarDecl>(DS->getSingleDecl());
if (!D || D->isInvalidDecl())
return StmtError();
FirstType = D->getType();
// C99 6.8.5p3: The declaration part of a 'for' statement shall only
// declare identifiers for objects having storage class 'auto' or
// 'register'.
if (!D->hasLocalStorage())
return StmtError(Diag(D->getLocation(),
diag::err_non_local_variable_decl_in_for));
// If the type contained 'auto', deduce the 'auto' to 'id'.
if (FirstType->getContainedAutoType()) {
OpaqueValueExpr OpaqueId(D->getLocation(), Context.getObjCIdType(),
VK_RValue);
Expr *DeducedInit = &OpaqueId;
if (DeduceAutoType(D->getTypeSourceInfo(), DeducedInit, FirstType) ==
DAR_Failed)
DiagnoseAutoDeductionFailure(D, DeducedInit);
if (FirstType.isNull()) {
D->setInvalidDecl();
return StmtError();
}
D->setType(FirstType);
if (!inTemplateInstantiation()) {
SourceLocation Loc =
D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
Diag(Loc, diag::warn_auto_var_is_id)
<< D->getDeclName();
}
}
} else {
Expr *FirstE = cast<Expr>(First);
if (!FirstE->isTypeDependent() && !FirstE->isLValue())
return StmtError(Diag(First->getLocStart(),
diag::err_selector_element_not_lvalue)
<< First->getSourceRange());
FirstType = static_cast<Expr*>(First)->getType();
if (FirstType.isConstQualified())
Diag(ForLoc, diag::err_selector_element_const_type)
<< FirstType << First->getSourceRange();
}
if (!FirstType->isDependentType() &&
!FirstType->isObjCObjectPointerType() &&
!FirstType->isBlockPointerType())
return StmtError(Diag(ForLoc, diag::err_selector_element_type)
<< FirstType << First->getSourceRange());
}
if (CollectionExprResult.isInvalid())
return StmtError();
CollectionExprResult = ActOnFinishFullExpr(CollectionExprResult.get());
if (CollectionExprResult.isInvalid())
return StmtError();
return new (Context) ObjCForCollectionStmt(First, CollectionExprResult.get(),
nullptr, ForLoc, RParenLoc);
}
/// Finish building a variable declaration for a for-range statement.
/// \return true if an error occurs.
static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
SourceLocation Loc, int DiagID) {
if (Decl->getType()->isUndeducedType()) {
ExprResult Res = SemaRef.CorrectDelayedTyposInExpr(Init);
if (!Res.isUsable()) {
Decl->setInvalidDecl();
return true;
}
Init = Res.get();
}
// Deduce the type for the iterator variable now rather than leaving it to
// AddInitializerToDecl, so we can produce a more suitable diagnostic.
QualType InitType;
if ((!isa<InitListExpr>(Init) && Init->getType()->isVoidType()) ||
SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitType) ==
Sema::DAR_Failed)
SemaRef.Diag(Loc, DiagID) << Init->getType();
if (InitType.isNull()) {
Decl->setInvalidDecl();
return true;
}
Decl->setType(InitType);
// In ARC, infer lifetime.
// FIXME: ARC may want to turn this into 'const __unsafe_unretained' if
// we're doing the equivalent of fast iteration.
if (SemaRef.getLangOpts().ObjCAutoRefCount &&
SemaRef.inferObjCARCLifetime(Decl))
Decl->setInvalidDecl();
SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false);
SemaRef.FinalizeDeclaration(Decl);
SemaRef.CurContext->addHiddenDecl(Decl);
return false;
}
namespace {
// An enum to represent whether something is dealing with a call to begin()
// or a call to end() in a range-based for loop.
enum BeginEndFunction {
BEF_begin,
BEF_end
};
/// Produce a note indicating which begin/end function was implicitly called
/// by a C++11 for-range statement. This is often not obvious from the code,
/// nor from the diagnostics produced when analysing the implicit expressions
/// required in a for-range statement.
void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
BeginEndFunction BEF) {
CallExpr *CE = dyn_cast<CallExpr>(E);
if (!CE)
return;
FunctionDecl *D = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
if (!D)
return;
SourceLocation Loc = D->getLocation();
std::string Description;
bool IsTemplate = false;
if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) {
Description = SemaRef.getTemplateArgumentBindingsText(
FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs());
IsTemplate = true;
}
SemaRef.Diag(Loc, diag::note_for_range_begin_end)
<< BEF << IsTemplate << Description << E->getType();
}
/// Build a variable declaration for a for-range statement.
VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
QualType Type, const char *Name) {
DeclContext *DC = SemaRef.CurContext;
IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc);
VarDecl *Decl = VarDecl::Create(SemaRef.Context, DC, Loc, Loc, II, Type,
TInfo, SC_None);
Decl->setImplicit();
return Decl;
}
}
static bool ObjCEnumerationCollection(Expr *Collection) {
return !Collection->isTypeDependent()
&& Collection->getType()->getAs<ObjCObjectPointerType>() != nullptr;
}
/// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement.
///
/// C++11 [stmt.ranged]:
/// A range-based for statement is equivalent to
///
/// {
/// auto && __range = range-init;
/// for ( auto __begin = begin-expr,
/// __end = end-expr;
/// __begin != __end;
/// ++__begin ) {
/// for-range-declaration = *__begin;
/// statement
/// }
/// }
///
/// The body of the loop is not available yet, since it cannot be analysed until
/// we have determined the type of the for-range-declaration.
StmtResult Sema::ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc,
SourceLocation CoawaitLoc, Stmt *First,
SourceLocation ColonLoc, Expr *Range,
SourceLocation RParenLoc,
BuildForRangeKind Kind) {
if (!First)
return StmtError();
if (Range && ObjCEnumerationCollection(Range))
return ActOnObjCForCollectionStmt(ForLoc, First, Range, RParenLoc);
DeclStmt *DS = dyn_cast<DeclStmt>(First);
assert(DS && "first part of for range not a decl stmt");
if (!DS->isSingleDecl()) {
Diag(DS->getStartLoc(), diag::err_type_defined_in_for_range);
return StmtError();
}
Decl *LoopVar = DS->getSingleDecl();
if (LoopVar->isInvalidDecl() || !Range ||
DiagnoseUnexpandedParameterPack(Range, UPPC_Expression)) {
LoopVar->setInvalidDecl();
return StmtError();
}
// Build the coroutine state immediately and not later during template
// instantiation
if (!CoawaitLoc.isInvalid()) {
if (!ActOnCoroutineBodyStart(S, CoawaitLoc, "co_await"))
return StmtError();
}
// Build auto && __range = range-init
SourceLocation RangeLoc = Range->getLocStart();
VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc,
Context.getAutoRRefDeductType(),
"__range");
if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
diag::err_for_range_deduction_failure)) {
LoopVar->setInvalidDecl();
return StmtError();
}
// Claim the type doesn't contain auto: we've already done the checking.
DeclGroupPtrTy RangeGroup =
BuildDeclaratorGroup(MutableArrayRef<Decl *>((Decl **)&RangeVar, 1));
StmtResult RangeDecl = ActOnDeclStmt(RangeGroup, RangeLoc, RangeLoc);
if (RangeDecl.isInvalid()) {
LoopVar->setInvalidDecl();
return StmtError();
}
return BuildCXXForRangeStmt(ForLoc, CoawaitLoc, ColonLoc, RangeDecl.get(),
/*BeginStmt=*/nullptr, /*EndStmt=*/nullptr,
/*Cond=*/nullptr, /*Inc=*/nullptr,
DS, RParenLoc, Kind);
}
/// \brief Create the initialization, compare, and increment steps for
/// the range-based for loop expression.
/// This function does not handle array-based for loops,
/// which are created in Sema::BuildCXXForRangeStmt.
///
/// \returns a ForRangeStatus indicating success or what kind of error occurred.
/// BeginExpr and EndExpr are set and FRS_Success is returned on success;
/// CandidateSet and BEF are set and some non-success value is returned on
/// failure.
static Sema::ForRangeStatus
BuildNonArrayForRange(Sema &SemaRef, Expr *BeginRange, Expr *EndRange,
QualType RangeType, VarDecl *BeginVar, VarDecl *EndVar,
SourceLocation ColonLoc, SourceLocation CoawaitLoc,
OverloadCandidateSet *CandidateSet, ExprResult *BeginExpr,
ExprResult *EndExpr, BeginEndFunction *BEF) {
DeclarationNameInfo BeginNameInfo(
&SemaRef.PP.getIdentifierTable().get("begin"), ColonLoc);
DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get("end"),
ColonLoc);
LookupResult BeginMemberLookup(SemaRef, BeginNameInfo,
Sema::LookupMemberName);
LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName);
if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) {
// - if _RangeT is a class type, the unqualified-ids begin and end are
// looked up in the scope of class _RangeT as if by class member access
// lookup (3.4.5), and if either (or both) finds at least one
// declaration, begin-expr and end-expr are __range.begin() and
// __range.end(), respectively;
SemaRef.LookupQualifiedName(BeginMemberLookup, D);
SemaRef.LookupQualifiedName(EndMemberLookup, D);
if (BeginMemberLookup.empty() != EndMemberLookup.empty()) {
SourceLocation RangeLoc = BeginVar->getLocation();
*BEF = BeginMemberLookup.empty() ? BEF_end : BEF_begin;
SemaRef.Diag(RangeLoc, diag::err_for_range_member_begin_end_mismatch)
<< RangeLoc << BeginRange->getType() << *BEF;
return Sema::FRS_DiagnosticIssued;
}
} else {
// - otherwise, begin-expr and end-expr are begin(__range) and
// end(__range), respectively, where begin and end are looked up with
// argument-dependent lookup (3.4.2). For the purposes of this name
// lookup, namespace std is an associated namespace.
}
*BEF = BEF_begin;
Sema::ForRangeStatus RangeStatus =
SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, BeginNameInfo,
BeginMemberLookup, CandidateSet,
BeginRange, BeginExpr);
if (RangeStatus != Sema::FRS_Success) {
if (RangeStatus == Sema::FRS_DiagnosticIssued)
SemaRef.Diag(BeginRange->getLocStart(), diag::note_in_for_range)
<< ColonLoc << BEF_begin << BeginRange->getType();
return RangeStatus;
}
if (!CoawaitLoc.isInvalid()) {
// FIXME: getCurScope() should not be used during template instantiation.
// We should pick up the set of unqualified lookup results for operator
// co_await during the initial parse.
*BeginExpr = SemaRef.ActOnCoawaitExpr(SemaRef.getCurScope(), ColonLoc,
BeginExpr->get());
if (BeginExpr->isInvalid())
return Sema::FRS_DiagnosticIssued;
}
if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc,
diag::err_for_range_iter_deduction_failure)) {
NoteForRangeBeginEndFunction(SemaRef, BeginExpr->get(), *BEF);
return Sema::FRS_DiagnosticIssued;
}
*BEF = BEF_end;
RangeStatus =
SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, EndNameInfo,
EndMemberLookup, CandidateSet,
EndRange, EndExpr);
if (RangeStatus != Sema::FRS_Success) {
if (RangeStatus == Sema::FRS_DiagnosticIssued)
SemaRef.Diag(EndRange->getLocStart(), diag::note_in_for_range)
<< ColonLoc << BEF_end << EndRange->getType();
return RangeStatus;
}
if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc,
diag::err_for_range_iter_deduction_failure)) {
NoteForRangeBeginEndFunction(SemaRef, EndExpr->get(), *BEF);
return Sema::FRS_DiagnosticIssued;
}
return Sema::FRS_Success;
}
/// Speculatively attempt to dereference an invalid range expression.
/// If the attempt fails, this function will return a valid, null StmtResult
/// and emit no diagnostics.
static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S,
SourceLocation ForLoc,
SourceLocation CoawaitLoc,
Stmt *LoopVarDecl,
SourceLocation ColonLoc,
Expr *Range,
SourceLocation RangeLoc,
SourceLocation RParenLoc) {
// Determine whether we can rebuild the for-range statement with a
// dereferenced range expression.
ExprResult AdjustedRange;
{
Sema::SFINAETrap Trap(SemaRef);
AdjustedRange = SemaRef.BuildUnaryOp(S, RangeLoc, UO_Deref, Range);
if (AdjustedRange.isInvalid())
return StmtResult();
StmtResult SR = SemaRef.ActOnCXXForRangeStmt(
S, ForLoc, CoawaitLoc, LoopVarDecl, ColonLoc, AdjustedRange.get(),
RParenLoc, Sema::BFRK_Check);
if (SR.isInvalid())
return StmtResult();
}
// The attempt to dereference worked well enough that it could produce a valid
// loop. Produce a fixit, and rebuild the loop with diagnostics enabled, in
// case there are any other (non-fatal) problems with it.
SemaRef.Diag(RangeLoc, diag::err_for_range_dereference)
<< Range->getType() << FixItHint::CreateInsertion(RangeLoc, "*");
return SemaRef.ActOnCXXForRangeStmt(S, ForLoc, CoawaitLoc, LoopVarDecl,
ColonLoc, AdjustedRange.get(), RParenLoc,
Sema::BFRK_Rebuild);
}
namespace {
/// RAII object to automatically invalidate a declaration if an error occurs.
struct InvalidateOnErrorScope {
InvalidateOnErrorScope(Sema &SemaRef, Decl *D, bool Enabled)
: Trap(SemaRef.Diags), D(D), Enabled(Enabled) {}
~InvalidateOnErrorScope() {
if (Enabled && Trap.hasErrorOccurred())
D->setInvalidDecl();
}
DiagnosticErrorTrap Trap;
Decl *D;
bool Enabled;
};
}
/// BuildCXXForRangeStmt - Build or instantiate a C++11 for-range statement.
StmtResult
Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation CoawaitLoc,
SourceLocation ColonLoc, Stmt *RangeDecl,
Stmt *Begin, Stmt *End, Expr *Cond,
Expr *Inc, Stmt *LoopVarDecl,
SourceLocation RParenLoc, BuildForRangeKind Kind) {
// FIXME: This should not be used during template instantiation. We should
// pick up the set of unqualified lookup results for the != and + operators
// in the initial parse.
//
// Testcase (accepts-invalid):
// template<typename T> void f() { for (auto x : T()) {} }
// namespace N { struct X { X begin(); X end(); int operator*(); }; }
// bool operator!=(N::X, N::X); void operator++(N::X);
// void g() { f<N::X>(); }
Scope *S = getCurScope();
DeclStmt *RangeDS = cast<DeclStmt>(RangeDecl);
VarDecl *RangeVar = cast<VarDecl>(RangeDS->getSingleDecl());
QualType RangeVarType = RangeVar->getType();
DeclStmt *LoopVarDS = cast<DeclStmt>(LoopVarDecl);
VarDecl *LoopVar = cast<VarDecl>(LoopVarDS->getSingleDecl());
// If we hit any errors, mark the loop variable as invalid if its type
// contains 'auto'.
InvalidateOnErrorScope Invalidate(*this, LoopVar,
LoopVar->getType()->isUndeducedType());
StmtResult BeginDeclStmt = Begin;
StmtResult EndDeclStmt = End;
ExprResult NotEqExpr = Cond, IncrExpr = Inc;
if (RangeVarType->isDependentType()) {
// The range is implicitly used as a placeholder when it is dependent.
RangeVar->markUsed(Context);
// Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill
// them in properly when we instantiate the loop.
if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
if (auto *DD = dyn_cast<DecompositionDecl>(LoopVar))
for (auto *Binding : DD->bindings())
Binding->setType(Context.DependentTy);
LoopVar->setType(SubstAutoType(LoopVar->getType(), Context.DependentTy));
}
} else if (!BeginDeclStmt.get()) {
SourceLocation RangeLoc = RangeVar->getLocation();
const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
VK_LValue, ColonLoc);
if (BeginRangeRef.isInvalid())
return StmtError();
ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
VK_LValue, ColonLoc);
if (EndRangeRef.isInvalid())
return StmtError();
QualType AutoType = Context.getAutoDeductType();
Expr *Range = RangeVar->getInit();
if (!Range)
return StmtError();
QualType RangeType = Range->getType();
if (RequireCompleteType(RangeLoc, RangeType,
diag::err_for_range_incomplete_type))
return StmtError();
// Build auto __begin = begin-expr, __end = end-expr.
VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
"__begin");
VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
"__end");
// Build begin-expr and end-expr and attach to __begin and __end variables.
ExprResult BeginExpr, EndExpr;
if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) {
// - if _RangeT is an array type, begin-expr and end-expr are __range and
// __range + __bound, respectively, where __bound is the array bound. If
// _RangeT is an array of unknown size or an array of incomplete type,
// the program is ill-formed;
// begin-expr is __range.
BeginExpr = BeginRangeRef;
if (!CoawaitLoc.isInvalid()) {
BeginExpr = ActOnCoawaitExpr(S, ColonLoc, BeginExpr.get());
if (BeginExpr.isInvalid())
return StmtError();
}
if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc,
diag::err_for_range_iter_deduction_failure)) {
NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
return StmtError();
}
// Find the array bound.
ExprResult BoundExpr;
if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(UnqAT))
BoundExpr = IntegerLiteral::Create(
Context, CAT->getSize(), Context.getPointerDiffType(), RangeLoc);
else if (const VariableArrayType *VAT =
dyn_cast<VariableArrayType>(UnqAT)) {
// For a variably modified type we can't just use the expression within
// the array bounds, since we don't want that to be re-evaluated here.
// Rather, we need to determine what it was when the array was first
// created - so we resort to using sizeof(vla)/sizeof(element).
// For e.g.
// void f(int b) {
// int vla[b];
// b = -1; <-- This should not affect the num of iterations below
// for (int &c : vla) { .. }
// }
// FIXME: This results in codegen generating IR that recalculates the
// run-time number of elements (as opposed to just using the IR Value
// that corresponds to the run-time value of each bound that was
// generated when the array was created.) If this proves too embarassing
// even for unoptimized IR, consider passing a magic-value/cookie to
// codegen that then knows to simply use that initial llvm::Value (that
// corresponds to the bound at time of array creation) within
// getelementptr. But be prepared to pay the price of increasing a
// customized form of coupling between the two components - which could
// be hard to maintain as the codebase evolves.
ExprResult SizeOfVLAExprR = ActOnUnaryExprOrTypeTraitExpr(
EndVar->getLocation(), UETT_SizeOf,
/*isType=*/true,
CreateParsedType(VAT->desugar(), Context.getTrivialTypeSourceInfo(
VAT->desugar(), RangeLoc))
.getAsOpaquePtr(),
EndVar->getSourceRange());
if (SizeOfVLAExprR.isInvalid())
return StmtError();
ExprResult SizeOfEachElementExprR = ActOnUnaryExprOrTypeTraitExpr(
EndVar->getLocation(), UETT_SizeOf,
/*isType=*/true,
CreateParsedType(VAT->desugar(),
Context.getTrivialTypeSourceInfo(
VAT->getElementType(), RangeLoc))
.getAsOpaquePtr(),
EndVar->getSourceRange());
if (SizeOfEachElementExprR.isInvalid())
return StmtError();
BoundExpr =
ActOnBinOp(S, EndVar->getLocation(), tok::slash,
SizeOfVLAExprR.get(), SizeOfEachElementExprR.get());
if (BoundExpr.isInvalid())
return StmtError();
} else {
// Can't be a DependentSizedArrayType or an IncompleteArrayType since
// UnqAT is not incomplete and Range is not type-dependent.
llvm_unreachable("Unexpected array type in for-range");
}
// end-expr is __range + __bound.
EndExpr = ActOnBinOp(S, ColonLoc, tok::plus, EndRangeRef.get(),
BoundExpr.get());
if (EndExpr.isInvalid())
return StmtError();
if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc,
diag::err_for_range_iter_deduction_failure)) {
NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
return StmtError();
}
} else {
OverloadCandidateSet CandidateSet(RangeLoc,
OverloadCandidateSet::CSK_Normal);
BeginEndFunction BEFFailure;
ForRangeStatus RangeStatus = BuildNonArrayForRange(
*this, BeginRangeRef.get(), EndRangeRef.get(), RangeType, BeginVar,
EndVar, ColonLoc, CoawaitLoc, &CandidateSet, &BeginExpr, &EndExpr,
&BEFFailure);
if (Kind == BFRK_Build && RangeStatus == FRS_NoViableFunction &&
BEFFailure == BEF_begin) {
// If the range is being built from an array parameter, emit a
// a diagnostic that it is being treated as a pointer.
if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Range)) {
if (ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
QualType ArrayTy = PVD->getOriginalType();
QualType PointerTy = PVD->getType();
if (PointerTy->isPointerType() && ArrayTy->isArrayType()) {
Diag(Range->getLocStart(), diag::err_range_on_array_parameter)
<< RangeLoc << PVD << ArrayTy << PointerTy;
Diag(PVD->getLocation(), diag::note_declared_at);
return StmtError();
}
}
}
// If building the range failed, try dereferencing the range expression
// unless a diagnostic was issued or the end function is problematic.
StmtResult SR = RebuildForRangeWithDereference(*this, S, ForLoc,
CoawaitLoc,
LoopVarDecl, ColonLoc,
Range, RangeLoc,
RParenLoc);
if (SR.isInvalid() || SR.isUsable())
return SR;
}
// Otherwise, emit diagnostics if we haven't already.
if (RangeStatus == FRS_NoViableFunction) {
Expr *Range = BEFFailure ? EndRangeRef.get() : BeginRangeRef.get();
Diag(Range->getLocStart(), diag::err_for_range_invalid)
<< RangeLoc << Range->getType() << BEFFailure;
CandidateSet.NoteCandidates(*this, OCD_AllCandidates, Range);
}
// Return an error if no fix was discovered.
if (RangeStatus != FRS_Success)
return StmtError();
}
assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() &&
"invalid range expression in for loop");
// C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same.
// C++1z removes this restriction.
QualType BeginType = BeginVar->getType(), EndType = EndVar->getType();
if (!Context.hasSameType(BeginType, EndType)) {
Diag(RangeLoc, getLangOpts().CPlusPlus17
? diag::warn_for_range_begin_end_types_differ
: diag::ext_for_range_begin_end_types_differ)
<< BeginType << EndType;
NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
}
BeginDeclStmt =
ActOnDeclStmt(ConvertDeclToDeclGroup(BeginVar), ColonLoc, ColonLoc);
EndDeclStmt =
ActOnDeclStmt(ConvertDeclToDeclGroup(EndVar), ColonLoc, ColonLoc);
const QualType BeginRefNonRefType = BeginType.getNonReferenceType();
ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
VK_LValue, ColonLoc);
if (BeginRef.isInvalid())
return StmtError();
ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(),
VK_LValue, ColonLoc);
if (EndRef.isInvalid())
return StmtError();
// Build and check __begin != __end expression.
NotEqExpr = ActOnBinOp(S, ColonLoc, tok::exclaimequal,
BeginRef.get(), EndRef.get());
if (!NotEqExpr.isInvalid())
NotEqExpr = CheckBooleanCondition(ColonLoc, NotEqExpr.get());
if (!NotEqExpr.isInvalid())
NotEqExpr = ActOnFinishFullExpr(NotEqExpr.get());
if (NotEqExpr.isInvalid()) {
Diag(RangeLoc, diag::note_for_range_invalid_iterator)
<< RangeLoc << 0 << BeginRangeRef.get()->getType();
NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
if (!Context.hasSameType(BeginType, EndType))
NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
return StmtError();
}
// Build and check ++__begin expression.
BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
VK_LValue, ColonLoc);
if (BeginRef.isInvalid())
return StmtError();
IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get());
if (!IncrExpr.isInvalid() && CoawaitLoc.isValid())
// FIXME: getCurScope() should not be used during template instantiation.
// We should pick up the set of unqualified lookup results for operator
// co_await during the initial parse.
IncrExpr = ActOnCoawaitExpr(S, CoawaitLoc, IncrExpr.get());
if (!IncrExpr.isInvalid())
IncrExpr = ActOnFinishFullExpr(IncrExpr.get());
if (IncrExpr.isInvalid()) {
Diag(RangeLoc, diag::note_for_range_invalid_iterator)
<< RangeLoc << 2 << BeginRangeRef.get()->getType() ;
NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
return StmtError();
}
// Build and check *__begin expression.
BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
VK_LValue, ColonLoc);
if (BeginRef.isInvalid())
return StmtError();
ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get());
if (DerefExpr.isInvalid()) {
Diag(RangeLoc, diag::note_for_range_invalid_iterator)
<< RangeLoc << 1 << BeginRangeRef.get()->getType();
NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
return StmtError();
}
// Attach *__begin as initializer for VD. Don't touch it if we're just
// trying to determine whether this would be a valid range.
if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false);
if (LoopVar->isInvalidDecl())
NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
}
}
// Don't bother to actually allocate the result if we're just trying to
// determine whether it would be valid.
if (Kind == BFRK_Check)
return StmtResult();
return new (Context) CXXForRangeStmt(
RangeDS, cast_or_null<DeclStmt>(BeginDeclStmt.get()),
cast_or_null<DeclStmt>(EndDeclStmt.get()), NotEqExpr.get(),
IncrExpr.get(), LoopVarDS, /*Body=*/nullptr, ForLoc, CoawaitLoc,
ColonLoc, RParenLoc);
}
/// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach
/// statement.
StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) {
if (!S || !B)
return StmtError();
ObjCForCollectionStmt * ForStmt = cast<ObjCForCollectionStmt>(S);
ForStmt->setBody(B);
return S;
}
// Warn when the loop variable is a const reference that creates a copy.
// Suggest using the non-reference type for copies. If a copy can be prevented
// suggest the const reference type that would do so.
// For instance, given "for (const &Foo : Range)", suggest
// "for (const Foo : Range)" to denote a copy is made for the loop. If
// possible, also suggest "for (const &Bar : Range)" if this type prevents
// the copy altogether.
static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef,
const VarDecl *VD,
QualType RangeInitType) {
const Expr *InitExpr = VD->getInit();
if (!InitExpr)
return;
QualType VariableType = VD->getType();
if (auto Cleanups = dyn_cast<ExprWithCleanups>(InitExpr))
if (!Cleanups->cleanupsHaveSideEffects())
InitExpr = Cleanups->getSubExpr();
const MaterializeTemporaryExpr *MTE =
dyn_cast<MaterializeTemporaryExpr>(InitExpr);
// No copy made.
if (!MTE)
return;
const Expr *E = MTE->GetTemporaryExpr()->IgnoreImpCasts();
// Searching for either UnaryOperator for dereference of a pointer or
// CXXOperatorCallExpr for handling iterators.
while (!isa<CXXOperatorCallExpr>(E) && !isa<UnaryOperator>(E)) {
if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(E)) {
E = CCE->getArg(0);
} else if (const CXXMemberCallExpr *Call = dyn_cast<CXXMemberCallExpr>(E)) {
const MemberExpr *ME = cast<MemberExpr>(Call->getCallee());
E = ME->getBase();
} else {
const MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E);
E = MTE->GetTemporaryExpr();
}
E = E->IgnoreImpCasts();
}
bool ReturnsReference = false;
if (isa<UnaryOperator>(E)) {
ReturnsReference = true;
} else {
const CXXOperatorCallExpr *Call = cast<CXXOperatorCallExpr>(E);
const FunctionDecl *FD = Call->getDirectCallee();
QualType ReturnType = FD->getReturnType();
ReturnsReference = ReturnType->isReferenceType();
}
if (ReturnsReference) {
// Loop variable creates a temporary. Suggest either to go with
// non-reference loop variable to indiciate a copy is made, or
// the correct time to bind a const reference.
SemaRef.Diag(VD->getLocation(), diag::warn_for_range_const_reference_copy)
<< VD << VariableType << E->getType();
QualType NonReferenceType = VariableType.getNonReferenceType();
NonReferenceType.removeLocalConst();
QualType NewReferenceType =
SemaRef.Context.getLValueReferenceType(E->getType().withConst());
SemaRef.Diag(VD->getLocStart(), diag::note_use_type_or_non_reference)
<< NonReferenceType << NewReferenceType << VD->getSourceRange();
} else {
// The range always returns a copy, so a temporary is always created.
// Suggest removing the reference from the loop variable.
SemaRef.Diag(VD->getLocation(), diag::warn_for_range_variable_always_copy)
<< VD << RangeInitType;
QualType NonReferenceType = VariableType.getNonReferenceType();
NonReferenceType.removeLocalConst();
SemaRef.Diag(VD->getLocStart(), diag::note_use_non_reference_type)
<< NonReferenceType << VD->getSourceRange();
}
}
// Warns when the loop variable can be changed to a reference type to
// prevent a copy. For instance, if given "for (const Foo x : Range)" suggest
// "for (const Foo &x : Range)" if this form does not make a copy.
static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef,
const VarDecl *VD) {
const Expr *InitExpr = VD->getInit();
if (!InitExpr)
return;
QualType VariableType = VD->getType();
if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(InitExpr)) {
if (!CE->getConstructor()->isCopyConstructor())
return;
} else if (const CastExpr *CE = dyn_cast<CastExpr>(InitExpr)) {
if (CE->getCastKind