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[Clang] fix crash by avoiding invalidation of extern main declaration during strictness checks #104594

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Merged
merged 5 commits into from
Aug 16, 2024
Merged

[Clang] fix crash by avoiding invalidation of extern main declaration during strictness checks #104594

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9ffe477
[Clang] fix crash by avoiding invalidation of extern main declaration…
a-tarasyuk Aug 16, 2024
0ea146a
cleanup
a-tarasyuk Aug 16, 2024
3b87654
Merge branch 'main' of https://github.com/llvm/llvm-project into fix/…
a-tarasyuk Aug 16, 2024
4ca1469
simplify test
a-tarasyuk Aug 16, 2024
3234a79
test void main functions
a-tarasyuk Aug 16, 2024
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5 changes: 1 addition & 4 deletions clang/lib/Sema/SemaDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12230,12 +12230,9 @@ void Sema::CheckMain(FunctionDecl *FD, const DeclSpec &DS) {
// The main function shall not be declared with a linkage-specification.
if (FD->isExternCContext() ||
(FD->isExternCXXContext() &&
FD->getDeclContext()->getRedeclContext()->isTranslationUnit())) {
FD->getDeclContext()->getRedeclContext()->isTranslationUnit()))
Diag(FD->getLocation(), diag::ext_main_invalid_linkage_specification)
<< FD->getLanguageLinkage();
FD->setInvalidDecl();
return;
}

// C++11 [basic.start.main]p3:
// A program that [...] declares main to be inline, static or
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28 changes: 21 additions & 7 deletions clang/test/CXX/basic/basic.start/basic.start.main/p3.cpp
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Expand Up @@ -11,6 +11,8 @@
// RUN: %clang_cc1 -fsyntax-only -verify -pedantic %s -DTEST11
// RUN: %clang_cc1 -fsyntax-only -verify -pedantic %s -DTEST12
// RUN: %clang_cc1 -fsyntax-only -verify -pedantic %s -DTEST13
// RUN: %clang_cc1 -fsyntax-only -verify -pedantic %s -DTEST14
// RUN: %clang_cc1 -triple x86_64-linux -emit-llvm-only -verify -pedantic %s -DTEST15

#if TEST1
int main; // expected-error{{main cannot be declared as a variable in the global scope}}
Expand Down Expand Up @@ -78,12 +80,14 @@ namespace ns {
extern "C" struct A { int main(); }; // ok

namespace c {
extern "C" void main(); // expected-warning {{'main' should not be 'extern "C"'}}
extern "C" void main(); // expected-error {{'main' must return 'int'}} \
// expected-warning {{'main' should not be 'extern "C"'}}
}

extern "C" {
namespace Z {
void main(); // expected-warning {{'main' should not be 'extern "C"'}}
void main(); // expected-error {{'main' must return 'int'}} \
// expected-warning {{'main' should not be 'extern "C"'}}
}
}

Expand All @@ -102,11 +106,6 @@ extern "C++" {
int main(); // expected-warning {{'main' should not be 'extern "C++"'}}
}

extern "C" {
int main(); // expected-warning {{'main' should not be 'extern "C"'}}
}

extern "C" int main(); // expected-warning {{'main' should not be 'extern "C"'}}
extern "C++" int main(); // expected-warning {{'main' should not be 'extern "C++"'}}

namespace ns1 {
Expand All @@ -122,6 +121,21 @@ namespace ns2 {
extern "C++" void main() {} // ok
}

#elif TEST14
extern "C" {
int main(); // expected-warning {{'main' should not be 'extern "C"'}}
}

extern "C" int main(); // expected-warning {{'main' should not be 'extern "C"'}}

#elif TEST15
extern "C" __attribute__((visibility("default"))) __attribute__((weak))
int main(); // expected-warning {{'main' should not be 'extern "C"'}}

unsigned long g() {
return reinterpret_cast<unsigned long>(&main); // expected-warning {{referring to 'main' within an expression is a Clang extension}}
}

#else
#error Unknown Test
#endif
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