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//===--- InclusionRewriter.cpp - Rewrite includes into their expansions ---===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This code rewrites include invocations into their expansions. This gives you
// a file with all included files merged into it.
#include "clang/Rewrite/Frontend/Rewriters.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Frontend/PreprocessorOutputOptions.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/Pragma.h"
#include "clang/Lex/Preprocessor.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace llvm;
namespace {
class InclusionRewriter : public PPCallbacks {
/// Information about which #includes were actually performed,
/// created by preprocessor callbacks.
struct IncludedFile {
FileID Id;
SrcMgr::CharacteristicKind FileType;
const DirectoryLookup *DirLookup;
IncludedFile(FileID Id, SrcMgr::CharacteristicKind FileType,
const DirectoryLookup *DirLookup)
: Id(Id), FileType(FileType), DirLookup(DirLookup) {}
Preprocessor &PP; ///< Used to find inclusion directives.
SourceManager &SM; ///< Used to read and manage source files.
raw_ostream &OS; ///< The destination stream for rewritten contents.
StringRef MainEOL; ///< The line ending marker to use.
const llvm::MemoryBuffer *PredefinesBuffer; ///< The preprocessor predefines.
bool ShowLineMarkers; ///< Show #line markers.
bool UseLineDirectives; ///< Use of line directives or line markers.
/// Tracks where inclusions that change the file are found.
std::map<unsigned, IncludedFile> FileIncludes;
/// Tracks where inclusions that import modules are found.
std::map<unsigned, const Module *> ModuleIncludes;
/// Tracks where inclusions that enter modules (in a module build) are found.
std::map<unsigned, const Module *> ModuleEntryIncludes;
/// Tracks where #if and #elif directives get evaluated and whether to true.
std::map<unsigned, bool> IfConditions;
/// Used transitively for building up the FileIncludes mapping over the
/// various \c PPCallbacks callbacks.
SourceLocation LastInclusionLocation;
InclusionRewriter(Preprocessor &PP, raw_ostream &OS, bool ShowLineMarkers,
bool UseLineDirectives);
void Process(FileID FileId, SrcMgr::CharacteristicKind FileType,
const DirectoryLookup *DirLookup);
void setPredefinesBuffer(const llvm::MemoryBuffer *Buf) {
PredefinesBuffer = Buf;
void detectMainFileEOL();
void handleModuleBegin(Token &Tok) {
assert(Tok.getKind() == tok::annot_module_begin);
(Module *)Tok.getAnnotationValue()});
void FileChanged(SourceLocation Loc, FileChangeReason Reason,
SrcMgr::CharacteristicKind FileType,
FileID PrevFID) override;
void FileSkipped(const FileEntryRef &SkippedFile, const Token &FilenameTok,
SrcMgr::CharacteristicKind FileType) override;
void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
StringRef FileName, bool IsAngled,
CharSourceRange FilenameRange, const FileEntry *File,
StringRef SearchPath, StringRef RelativePath,
const Module *Imported,
SrcMgr::CharacteristicKind FileType) override;
void If(SourceLocation Loc, SourceRange ConditionRange,
ConditionValueKind ConditionValue) override;
void Elif(SourceLocation Loc, SourceRange ConditionRange,
ConditionValueKind ConditionValue, SourceLocation IfLoc) override;
void WriteLineInfo(StringRef Filename, int Line,
SrcMgr::CharacteristicKind FileType,
StringRef Extra = StringRef());
void WriteImplicitModuleImport(const Module *Mod);
void OutputContentUpTo(const MemoryBuffer &FromFile,
unsigned &WriteFrom, unsigned WriteTo,
StringRef EOL, int &lines,
bool EnsureNewline);
void CommentOutDirective(Lexer &DirectivesLex, const Token &StartToken,
const MemoryBuffer &FromFile, StringRef EOL,
unsigned &NextToWrite, int &Lines);
const IncludedFile *FindIncludeAtLocation(SourceLocation Loc) const;
const Module *FindModuleAtLocation(SourceLocation Loc) const;
const Module *FindEnteredModule(SourceLocation Loc) const;
bool IsIfAtLocationTrue(SourceLocation Loc) const;
StringRef NextIdentifierName(Lexer &RawLex, Token &RawToken);
} // end anonymous namespace
/// Initializes an InclusionRewriter with a \p PP source and \p OS destination.
InclusionRewriter::InclusionRewriter(Preprocessor &PP, raw_ostream &OS,
bool ShowLineMarkers,
bool UseLineDirectives)
: PP(PP), SM(PP.getSourceManager()), OS(OS), MainEOL("\n"),
PredefinesBuffer(nullptr), ShowLineMarkers(ShowLineMarkers),
LastInclusionLocation(SourceLocation()) {}
/// Write appropriate line information as either #line directives or GNU line
/// markers depending on what mode we're in, including the \p Filename and
/// \p Line we are located at, using the specified \p EOL line separator, and
/// any \p Extra context specifiers in GNU line directives.
void InclusionRewriter::WriteLineInfo(StringRef Filename, int Line,
SrcMgr::CharacteristicKind FileType,
StringRef Extra) {
if (!ShowLineMarkers)
if (UseLineDirectives) {
OS << "#line" << ' ' << Line << ' ' << '"';
OS << '"';
} else {
// Use GNU linemarkers as described here:
OS << '#' << ' ' << Line << ' ' << '"';
OS << '"';
if (!Extra.empty())
OS << Extra;
if (FileType == SrcMgr::C_System)
// "`3' This indicates that the following text comes from a system header
// file, so certain warnings should be suppressed."
OS << " 3";
else if (FileType == SrcMgr::C_ExternCSystem)
// as above for `3', plus "`4' This indicates that the following text
// should be treated as being wrapped in an implicit extern "C" block."
OS << " 3 4";
OS << MainEOL;
void InclusionRewriter::WriteImplicitModuleImport(const Module *Mod) {
OS << "#pragma clang module import " << Mod->getFullModuleName(true)
<< " /* clang -frewrite-includes: implicit import */" << MainEOL;
/// FileChanged - Whenever the preprocessor enters or exits a #include file
/// it invokes this handler.
void InclusionRewriter::FileChanged(SourceLocation Loc,
FileChangeReason Reason,
SrcMgr::CharacteristicKind NewFileType,
FileID) {
if (Reason != EnterFile)
if (LastInclusionLocation.isInvalid())
// we didn't reach this file (eg: the main file) via an inclusion directive
FileID Id = FullSourceLoc(Loc, SM).getFileID();
auto P = FileIncludes.insert(
IncludedFile(Id, NewFileType, PP.GetCurDirLookup())));
assert(P.second && "Unexpected revisitation of the same include directive");
LastInclusionLocation = SourceLocation();
/// Called whenever an inclusion is skipped due to canonical header protection
/// macros.
void InclusionRewriter::FileSkipped(const FileEntryRef & /*SkippedFile*/,
const Token & /*FilenameTok*/,
SrcMgr::CharacteristicKind /*FileType*/) {
assert(LastInclusionLocation.isValid() &&
"A file, that wasn't found via an inclusion directive, was skipped");
LastInclusionLocation = SourceLocation();
/// This should be called whenever the preprocessor encounters include
/// directives. It does not say whether the file has been included, but it
/// provides more information about the directive (hash location instead
/// of location inside the included file). It is assumed that the matching
/// FileChanged() or FileSkipped() is called after this (or neither is
/// called if this #include results in an error or does not textually include
/// anything).
void InclusionRewriter::InclusionDirective(SourceLocation HashLoc,
const Token &/*IncludeTok*/,
StringRef /*FileName*/,
bool /*IsAngled*/,
CharSourceRange /*FilenameRange*/,
const FileEntry * /*File*/,
StringRef /*SearchPath*/,
StringRef /*RelativePath*/,
const Module *Imported,
SrcMgr::CharacteristicKind FileType){
if (Imported) {
auto P = ModuleIncludes.insert(
std::make_pair(HashLoc.getRawEncoding(), Imported));
assert(P.second && "Unexpected revisitation of the same include directive");
} else
LastInclusionLocation = HashLoc;
void InclusionRewriter::If(SourceLocation Loc, SourceRange ConditionRange,
ConditionValueKind ConditionValue) {
auto P = IfConditions.insert(
std::make_pair(Loc.getRawEncoding(), ConditionValue == CVK_True));
assert(P.second && "Unexpected revisitation of the same if directive");
void InclusionRewriter::Elif(SourceLocation Loc, SourceRange ConditionRange,
ConditionValueKind ConditionValue,
SourceLocation IfLoc) {
auto P = IfConditions.insert(
std::make_pair(Loc.getRawEncoding(), ConditionValue == CVK_True));
assert(P.second && "Unexpected revisitation of the same elif directive");
/// Simple lookup for a SourceLocation (specifically one denoting the hash in
/// an inclusion directive) in the map of inclusion information, FileChanges.
const InclusionRewriter::IncludedFile *
InclusionRewriter::FindIncludeAtLocation(SourceLocation Loc) const {
const auto I = FileIncludes.find(Loc.getRawEncoding());
if (I != FileIncludes.end())
return &I->second;
return nullptr;
/// Simple lookup for a SourceLocation (specifically one denoting the hash in
/// an inclusion directive) in the map of module inclusion information.
const Module *
InclusionRewriter::FindModuleAtLocation(SourceLocation Loc) const {
const auto I = ModuleIncludes.find(Loc.getRawEncoding());
if (I != ModuleIncludes.end())
return I->second;
return nullptr;
/// Simple lookup for a SourceLocation (specifically one denoting the hash in
/// an inclusion directive) in the map of module entry information.
const Module *
InclusionRewriter::FindEnteredModule(SourceLocation Loc) const {
const auto I = ModuleEntryIncludes.find(Loc.getRawEncoding());
if (I != ModuleEntryIncludes.end())
return I->second;
return nullptr;
bool InclusionRewriter::IsIfAtLocationTrue(SourceLocation Loc) const {
const auto I = IfConditions.find(Loc.getRawEncoding());
if (I != IfConditions.end())
return I->second;
return false;
/// Detect the likely line ending style of \p FromFile by examining the first
/// newline found within it.
static StringRef DetectEOL(const MemoryBuffer &FromFile) {
// Detect what line endings the file uses, so that added content does not mix
// the style. We need to check for "\r\n" first because "\n\r" will match
// "\r\n\r\n".
const char *Pos = strchr(FromFile.getBufferStart(), '\n');
if (!Pos)
return "\n";
if (Pos - 1 >= FromFile.getBufferStart() && Pos[-1] == '\r')
return "\r\n";
if (Pos + 1 < FromFile.getBufferEnd() && Pos[1] == '\r')
return "\n\r";
return "\n";
void InclusionRewriter::detectMainFileEOL() {
bool Invalid;
const MemoryBuffer &FromFile = *SM.getBuffer(SM.getMainFileID(), &Invalid);
if (Invalid)
return; // Should never happen, but whatever.
MainEOL = DetectEOL(FromFile);
/// Writes out bytes from \p FromFile, starting at \p NextToWrite and ending at
/// \p WriteTo - 1.
void InclusionRewriter::OutputContentUpTo(const MemoryBuffer &FromFile,
unsigned &WriteFrom, unsigned WriteTo,
StringRef LocalEOL, int &Line,
bool EnsureNewline) {
if (WriteTo <= WriteFrom)
if (&FromFile == PredefinesBuffer) {
// Ignore the #defines of the predefines buffer.
WriteFrom = WriteTo;
// If we would output half of a line ending, advance one character to output
// the whole line ending. All buffers are null terminated, so looking ahead
// one byte is safe.
if (LocalEOL.size() == 2 &&
LocalEOL[0] == (FromFile.getBufferStart() + WriteTo)[-1] &&
LocalEOL[1] == (FromFile.getBufferStart() + WriteTo)[0])
StringRef TextToWrite(FromFile.getBufferStart() + WriteFrom,
WriteTo - WriteFrom);
if (MainEOL == LocalEOL) {
OS << TextToWrite;
// count lines manually, it's faster than getPresumedLoc()
Line += TextToWrite.count(LocalEOL);
if (EnsureNewline && !TextToWrite.endswith(LocalEOL))
OS << MainEOL;
} else {
// Output the file one line at a time, rewriting the line endings as we go.
StringRef Rest = TextToWrite;
while (!Rest.empty()) {
StringRef LineText;
std::tie(LineText, Rest) = Rest.split(LocalEOL);
OS << LineText;
if (!Rest.empty())
OS << MainEOL;
if (TextToWrite.endswith(LocalEOL) || EnsureNewline)
OS << MainEOL;
WriteFrom = WriteTo;
/// Print characters from \p FromFile starting at \p NextToWrite up until the
/// inclusion directive at \p StartToken, then print out the inclusion
/// inclusion directive disabled by a #if directive, updating \p NextToWrite
/// and \p Line to track the number of source lines visited and the progress
/// through the \p FromFile buffer.
void InclusionRewriter::CommentOutDirective(Lexer &DirectiveLex,
const Token &StartToken,
const MemoryBuffer &FromFile,
StringRef LocalEOL,
unsigned &NextToWrite, int &Line) {
OutputContentUpTo(FromFile, NextToWrite,
SM.getFileOffset(StartToken.getLocation()), LocalEOL, Line,
Token DirectiveToken;
do {
} while (! && DirectiveToken.isNot(tok::eof));
if (&FromFile == PredefinesBuffer) {
// OutputContentUpTo() would not output anything anyway.
OS << "#if 0 /* expanded by -frewrite-includes */" << MainEOL;
OutputContentUpTo(FromFile, NextToWrite,
SM.getFileOffset(DirectiveToken.getLocation()) +
LocalEOL, Line, true);
OS << "#endif /* expanded by -frewrite-includes */" << MainEOL;
/// Find the next identifier in the pragma directive specified by \p RawToken.
StringRef InclusionRewriter::NextIdentifierName(Lexer &RawLex,
Token &RawToken) {
if (
if (
return RawToken.getIdentifierInfo()->getName();
return StringRef();
/// Use a raw lexer to analyze \p FileId, incrementally copying parts of it
/// and including content of included files recursively.
void InclusionRewriter::Process(FileID FileId,
SrcMgr::CharacteristicKind FileType,
const DirectoryLookup *DirLookup) {
bool Invalid;
const MemoryBuffer &FromFile = *SM.getBuffer(FileId, &Invalid);
assert(!Invalid && "Attempting to process invalid inclusion");
StringRef FileName = FromFile.getBufferIdentifier();
Lexer RawLex(FileId, &FromFile, PP.getSourceManager(), PP.getLangOpts());
StringRef LocalEOL = DetectEOL(FromFile);
// Per the GNU docs: "1" indicates entering a new file.
if (FileId == SM.getMainFileID() || FileId == PP.getPredefinesFileID())
WriteLineInfo(FileName, 1, FileType, "");
WriteLineInfo(FileName, 1, FileType, " 1");
if (SM.getFileIDSize(FileId) == 0)
// The next byte to be copied from the source file, which may be non-zero if
// the lexer handled a BOM.
unsigned NextToWrite = SM.getFileOffset(RawLex.getSourceLocation());
assert(SM.getLineNumber(FileId, NextToWrite) == 1);
int Line = 1; // The current input file line number.
Token RawToken;
// TODO: Consider adding a switch that strips possibly unimportant content,
// such as comments, to reduce the size of repro files.
while (RawToken.isNot(tok::eof)) {
if ( && RawToken.isAtStartOfLine()) {
Token HashToken = RawToken;
if (
if (RawToken.getIdentifierInfo() != nullptr) {
switch (RawToken.getIdentifierInfo()->getPPKeywordID()) {
case tok::pp_include:
case tok::pp_include_next:
case tok::pp_import: {
CommentOutDirective(RawLex, HashToken, FromFile, LocalEOL, NextToWrite,
if (FileId != PP.getPredefinesFileID())
WriteLineInfo(FileName, Line - 1, FileType, "");
StringRef LineInfoExtra;
SourceLocation Loc = HashToken.getLocation();
if (const Module *Mod = FindModuleAtLocation(Loc))
else if (const IncludedFile *Inc = FindIncludeAtLocation(Loc)) {
const Module *Mod = FindEnteredModule(Loc);
if (Mod)
OS << "#pragma clang module begin "
<< Mod->getFullModuleName(true) << "\n";
// Include and recursively process the file.
Process(Inc->Id, Inc->FileType, Inc->DirLookup);
if (Mod)
OS << "#pragma clang module end /*"
<< Mod->getFullModuleName(true) << "*/\n";
// Add line marker to indicate we're returning from an included
// file.
LineInfoExtra = " 2";
// fix up lineinfo (since commented out directive changed line
// numbers) for inclusions that were skipped due to header guards
WriteLineInfo(FileName, Line, FileType, LineInfoExtra);
case tok::pp_pragma: {
StringRef Identifier = NextIdentifierName(RawLex, RawToken);
if (Identifier == "clang" || Identifier == "GCC") {
if (NextIdentifierName(RawLex, RawToken) == "system_header") {
// keep the directive in, commented out
CommentOutDirective(RawLex, HashToken, FromFile, LocalEOL,
NextToWrite, Line);
// update our own type
FileType = SM.getFileCharacteristic(RawToken.getLocation());
WriteLineInfo(FileName, Line, FileType);
} else if (Identifier == "once") {
// keep the directive in, commented out
CommentOutDirective(RawLex, HashToken, FromFile, LocalEOL,
NextToWrite, Line);
WriteLineInfo(FileName, Line, FileType);
case tok::pp_if:
case tok::pp_elif: {
bool elif = (RawToken.getIdentifierInfo()->getPPKeywordID() ==
bool isTrue = IsIfAtLocationTrue(RawToken.getLocation());
OutputContentUpTo(FromFile, NextToWrite,
LocalEOL, Line, /*EnsureNewline=*/true);
do {
} while (! && RawToken.isNot(tok::eof));
// We need to disable the old condition, but that is tricky.
// Trying to comment it out can easily lead to comment nesting.
// So instead make the condition harmless by making it enclose
// and empty block. Moreover, put it itself inside an #if 0 block
// to disable it from getting evaluated (e.g. __has_include_next
// warns if used from the primary source file).
OS << "#if 0 /* disabled by -frewrite-includes */" << MainEOL;
if (elif) {
OS << "#if 0" << MainEOL;
OutputContentUpTo(FromFile, NextToWrite,
SM.getFileOffset(RawToken.getLocation()) +
LocalEOL, Line, /*EnsureNewline=*/true);
// Close the empty block and the disabling block.
OS << "#endif" << MainEOL;
OS << "#endif /* disabled by -frewrite-includes */" << MainEOL;
OS << (elif ? "#elif " : "#if ") << (isTrue ? "1" : "0")
<< " /* evaluated by -frewrite-includes */" << MainEOL;
WriteLineInfo(FileName, Line, FileType);
case tok::pp_endif:
case tok::pp_else: {
// We surround every #include by #if 0 to comment it out, but that
// changes line numbers. These are fixed up right after that, but
// the whole #include could be inside a preprocessor conditional
// that is not processed. So it is necessary to fix the line
// numbers one the next line after each #else/#endif as well.
do {
} while (RawToken.isNot(tok::eod) && RawToken.isNot(tok::eof));
OutputContentUpTo(FromFile, NextToWrite,
SM.getFileOffset(RawToken.getLocation()) +
LocalEOL, Line, /*EnsureNewline=*/ true);
WriteLineInfo(FileName, Line, FileType);
OutputContentUpTo(FromFile, NextToWrite,
SM.getFileOffset(SM.getLocForEndOfFile(FileId)), LocalEOL,
Line, /*EnsureNewline=*/true);
/// InclusionRewriterInInput - Implement -frewrite-includes mode.
void clang::RewriteIncludesInInput(Preprocessor &PP, raw_ostream *OS,
const PreprocessorOutputOptions &Opts) {
SourceManager &SM = PP.getSourceManager();
InclusionRewriter *Rewrite = new InclusionRewriter(
PP, *OS, Opts.ShowLineMarkers, Opts.UseLineDirectives);
// First let the preprocessor process the entire file and call callbacks.
// Callbacks will record which #include's were actually performed.
Token Tok;
// Only preprocessor directives matter here, so disable macro expansion
// everywhere else as an optimization.
// TODO: It would be even faster if the preprocessor could be switched
// to a mode where it would parse only preprocessor directives and comments,
// nothing else matters for parsing or processing.
do {
if (
} while (Tok.isNot(tok::eof));
Rewrite->Process(PP.getPredefinesFileID(), SrcMgr::C_User, nullptr);
Rewrite->Process(SM.getMainFileID(), SrcMgr::C_User, nullptr);