commit | b77109ff8c17cd20ac2c791761028a358c9e3447 | [log] [tgz] |
---|---|---|
author | JJ Marr <168750718+jj-marr@users.noreply.github.com> | Wed May 14 02:47:38 2025 -0400 |
committer | GitHub <noreply@github.com> | Wed May 14 08:47:38 2025 +0200 |
tree | 52b8e7953a800901f35b37ed553bfaf25343b75a | |
parent | 6c1bb48cc45396894597c8cb897c31205d1bdeb6 [diff] |
Better diagnostics when assertion fails in `consteval` (#130458) Take this piece of code: ```cpp #include <cassert> consteval int square(int x) { int result = x * x; assert(result == 42); return result; } void test() { auto val = square(2); } ``` The assertion will fail, and `clang++` will output (https://godbolt.org/z/hjz3KbTTv): ```cpp <source>:10:14: error: call to consteval function 'square' is not a constant expression 10 | auto val = square(2); | ^ <source>:5:3: note: non-constexpr function '__assert_fail' cannot be used in a constant expression 5 | assert(result == 42); | ^ /usr/include/assert.h:95:9: note: expanded from macro 'assert' 95 | : __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION)) | ^ <source>:10:14: note: in call to 'square(2)' 10 | auto val = square(2); | ^~~~~~~~~ /usr/include/assert.h:69:13: note: declared here 69 | extern void __assert_fail (const char *__assertion, const char *__file, | ^ 1 error generated. Compiler returned: 1 ``` This is confusing because it implies that the issue was using an assertion in a constant-evaluted context, and not that the assertion failed (`assert()` is OK in constant evaluation). This PR changes the error message to: ```cpp test.cpp:10:14: error: call to consteval function 'square' is not a constant expression 10 | auto val = square(2); | ^ test.cpp:5:3: note: assertion failed in consteval context: 'result == 42' 5 | assert(result == 42); | ^ /nix/store/lw21wr626v5sdcaxxkv2k4zf1121hfc9-glibc-2.40-36-dev/include/assert.h:102:9: note: expanded from macro 'assert' 102 | : __assert_fail (#expr, __ASSERT_FILE, __ASSERT_LINE, \ | ^ test.cpp:10:14: note: in call to 'square(2)' 10 | auto val = square(2); | ^~~~~~~~~ 1 error generated.```
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