Index: cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td =================================================================== --- cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td +++ cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td @@ -173,6 +173,9 @@ def warn_gcc_attribute_location : Warning< "GCC does not allow an attribute in this position on a function declaration">, InGroup; +def warn_gcc_variable_decl_in_for_loop : Warning< + "GCC does not allow variable declarations in for loop initializers before " + "C99">, InGroup; def warn_attribute_no_decl : Warning< "attribute %0 ignored, because it is not attached to a declaration">, InGroup; Index: cfe/trunk/lib/Parse/ParseStmt.cpp =================================================================== --- cfe/trunk/lib/Parse/ParseStmt.cpp +++ cfe/trunk/lib/Parse/ParseStmt.cpp @@ -1624,8 +1624,10 @@ ParenBraceBracketBalancer BalancerRAIIObj(*this); // Parse declaration, which eats the ';'. - if (!C99orCXXorObjC) // Use of C99-style for loops in C90 mode? + if (!C99orCXXorObjC) { // Use of C99-style for loops in C90 mode? Diag(Tok, diag::ext_c99_variable_decl_in_for_loop); + Diag(Tok, diag::warn_gcc_variable_decl_in_for_loop); + } // In C++0x, "for (T NS:a" might not be a typo for :: bool MightBeForRangeStmt = getLangOpts().CPlusPlus; Index: cfe/trunk/test/Parser/gcc-for-loop-init-compatibility.c =================================================================== --- cfe/trunk/test/Parser/gcc-for-loop-init-compatibility.c +++ cfe/trunk/test/Parser/gcc-for-loop-init-compatibility.c @@ -0,0 +1,15 @@ +// RUN: %clang_cc1 -std=c89 -fsyntax-only -verify %s +// RUN: %clang_cc1 -std=gnu89 -fsyntax-only -verify %s +// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify %s -DC99 + +#ifdef C99 +// expected-no-diagnostics +#endif + +void foo() { +#ifndef C99 + // expected-warning@+2{{GCC does not allow variable declarations in for loop initializers before C99}} +#endif + for (int i = 0; i < 10; i++) + ; +}