test/Sema/builtin-redecl.cpp

// RUN: %clang_cc1 %s -fsyntax-only -verify 
// RUN: %clang_cc1 %s -fsyntax-only -verify -x c
// RUN: %clang_cc1 %s -fsyntax-only -verify -fms-compatibility

// Redeclaring library builtins is OK.
void exit(int);

// expected-error@+2 {{cannot redeclare builtin function '__builtin_va_copy'}}
// expected-note@+1 {{'__builtin_va_copy' is a builtin with type}}
void __builtin_va_copy(double d);

// expected-error@+2 {{cannot redeclare builtin function '__builtin_va_end'}}
// expected-note@+1 {{'__builtin_va_end' is a builtin with type}}
void __builtin_va_end(__builtin_va_list);
// RUN: %clang_cc1 %s -fsyntax-only -verify 
// RUN: %clang_cc1 %s -fsyntax-only -verify -x c

void __va_start(__builtin_va_list*, ...);