diff options
| -rw-r--r-- | lib/Sema/SemaDecl.cpp | 32 | ||||
| -rw-r--r-- | test/Sema/extern-redecl.c | 20 |
2 files changed, 41 insertions, 11 deletions
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp index b3cbbf203e..52d39d323f 100644 --- a/lib/Sema/SemaDecl.cpp +++ b/lib/Sema/SemaDecl.cpp @@ -2697,21 +2697,31 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, Decl *OldD, Scope *S) { // Fall through to diagnose conflicting types. } - // A function that has already been declared has been redeclared or defined - // with a different type- show appropriate diagnostic - if (unsigned BuiltinID = Old->getBuiltinID()) { - // The user has declared a builtin function with an incompatible - // signature. + // A function that has already been declared has been redeclared or + // defined with a different type; show an appropriate diagnostic. + + // If the previous declaration was an implicitly-generated builtin + // declaration, then at the very least we should use a specialized note. + unsigned BuiltinID; + if (Old->isImplicit() && (BuiltinID = Old->getBuiltinID())) { + // If it's actually a library-defined builtin function like 'malloc' + // or 'printf', just warn about the incompatible redeclaration. if (Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) { - // The function the user is redeclaring is a library-defined - // function like 'malloc' or 'printf'. Warn about the - // redeclaration, then pretend that we don't know about this - // library built-in. Diag(New->getLocation(), diag::warn_redecl_library_builtin) << New; Diag(Old->getLocation(), diag::note_previous_builtin_declaration) << Old << Old->getType(); - New->getIdentifier()->setBuiltinID(Builtin::NotBuiltin); - Old->setInvalidDecl(); + + // If this is a global redeclaration, just forget hereafter + // about the "builtin-ness" of the function. + // + // Doing this for local extern declarations is problematic. If + // the builtin declaration remains visible, a second invalid + // local declaration will produce a hard error; if it doesn't + // remain visible, a single bogus local redeclaration (which is + // actually only a warning) could break all the downstream code. + if (!New->getDeclContext()->isFunctionOrMethod()) + New->getIdentifier()->setBuiltinID(Builtin::NotBuiltin); + return false; } diff --git a/test/Sema/extern-redecl.c b/test/Sema/extern-redecl.c index 64885a08d3..e9a4c571bd 100644 --- a/test/Sema/extern-redecl.c +++ b/test/Sema/extern-redecl.c @@ -42,3 +42,23 @@ void test4() { } int x = sizeof(test4_array); // expected-error {{invalid application of 'sizeof' to an incomplete type 'int []'}} } + +// Test that invalid local extern declarations of library +// builtins behave reasonably. +extern void abort(void); // expected-note 2 {{previous declaration is here}} +extern float *calloc(); // expected-warning {{incompatible redeclaration of library function}} expected-note {{is a builtin}} expected-note 2 {{previous declaration is here}} +void test5a() { + int abort(); // expected-error {{conflicting types}} + float *malloc(); // expected-warning {{incompatible redeclaration of library function}} expected-note 2 {{is a builtin}} + int *calloc(); // expected-error {{conflicting types}} +} +void test5b() { + int abort(); // expected-error {{conflicting types}} + float *malloc(); // expected-warning {{incompatible redeclaration of library function}} + int *calloc(); // expected-error {{conflicting types}} +} +void test5c() { + void (*_abort)(void) = &abort; + void *(*_malloc)() = &malloc; + float *(*_calloc)() = &calloc; +} |