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Handle incompatible redeclarations of library builtins better. 

Invalid redeclarations of valid explicit declarations shouldn't
take the same path as redeclarations of implicit declarations,
and invalid local extern declarations shouldn't foul things up
for everybody else.

llvm-svn: 179482
This commit is contained in:
John McCall 2013-04-14 08:50:55 +00:00
parent 512dc38f81
commit ad327cd214
2 changed files with 41 additions and 11 deletions
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32
clang/lib/Sema/SemaDecl.cpp
View File

@ -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;
}

20
clang/test/Sema/extern-redecl.c
View File

@ -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;
}