bugprone-infinite-loop false positive with CATCH2

[pavelkryukov]

Bugzilla Link	44816
Resolution	FIXED
Resolved on	Feb 17, 2020 04:50
Version	unspecified
OS	All
Depends On	#44239
Blocks	#43900
CC	@EugeneZelenko,@zmodem,@VReichelt
Fixed by commit(s)	rGc69ec6476806147e46bf09b693acb24177982dc2

Extended Description

bugprone-infinite-loop has a false positive for CATCH2 assertion macro.

Example: https://godbolt.org/z/bzHeuz

#include <catch.hpp>
int foo();
int bar();

TEST_CASE("Hello World")
{
int x = foo();
int y = bar();
CHECK( x < y);
}

Output:

clang-tidy (trunk) #​2 with x86-64 gcc 9.2
-checks='*,-modernize-use-trailing-return-type'

:10:5: warning: this loop is infinite; none of its condition variables (x, y) are updated in the loop body [bugprone-infinite-loop] CHECK( x < y); ^ /opt/compiler-explorer/libs/catch2/v2.11.1/include/catch.hpp:217:22: note: expanded from macro 'CHECK' #define CHECK( ... ) INTERNAL_CATCH_TEST( "CHECK", Catch::ResultDisposition::ContinueOnFailure, __VA_ARGS__ ) ^ /opt/compiler-explorer/libs/catch2/v2.11.1/include/internal/catch_capture.hpp:43:5: note: expanded from macro 'INTERNAL_CATCH_TEST' do { \ ^

[pavelkryukov]

The problematic loop is:

do {

} while( (void)0, false && static_cast( !!(VA_ARGS) ) )
// the expression here is never evaluated at runtime but it forces the compiler to give it a look

[llvmbot]

minimum reproducible test case

void fail(bool a) {
do {
} while (false && a);
}

Should ignore loops with conditions that always eval to false

[llvmbot]

Fixed in https://reviews.llvm.org/rGc69ec6476806147e46bf09b693acb24177982dc2

[pavelkryukov]

Thanks! Could you please tell if it lands to LLVM 10?

[EugeneZelenko]

Thanks! Could you please tell if it lands to LLVM 10?

It's necessary to create new merge request and make bug 44555 depended on it.

[pavelkryukov]

I’ve added the dependency - should I reopen the bug?

[llvmbot]

I've done it for you. But if it's not reopened it won't appear to block the release

[zmodem]

Fixed in https://reviews.llvm.org/rGc69ec6476806147e46bf09b693acb24177982dc2

Pushed to 10.x in 7a136d2.

[VReichelt]

This probably caused bug 44894.

[VReichelt]

mentioned in issue #44239

[horenmar]

mentioned in issue llvm/llvm-bugzilla-archive#52081