| commit | a150e8081ac2b4c7c056b0290afb88b9a01d7a1d | [log] [tgz] |
|---|---|---|
| author | Ayush Kumar Gaur <132849148+Ayush3941@users.noreply.github.com> | Mon Jan 26 11:01:02 2026 -0500 |
| committer | GitHub <noreply@github.com> | Mon Jan 26 17:01:02 2026 +0100 |
| tree | d19421b998e55c4f063f19440c72aa739b1c0f74 | |
| parent | b0ce26c320ec09940442ded28d7771043639377e [diff] |
[clang][bytecode] Avoid crash in constexpr wcslen on invalid argument… (#177891)
### What the problem ?
Fix a clang bytecode constant interpreter crash when evaluating
wcslen("x") in a constant-expression path.
Previously we asserted on wchar element size mismatch and crashed in
assertion builds.
### Why it happened
The expression is already ill-typed (char[2] → const wchar_t*), clang
correctly emits a diagnostic, but later ICE checking tries to fold the
expression and reaches the builtin handler. That path must not crash.
### whats the Fix
Replace the assert(ElemSize == wchar_t size) with a graceful failure
(return false / emit appropriate diagnostic) when element sizes don’t
match, so evaluation stops safely.
### how to Test it
Add a regression test that triggers ICE checking with
-fexperimental-new-constant-interpreter and ensures clang does not crash
(verifies it reports the type error / static_assert failure instead).
Fixes #177844.
<img width="1366" height="768" alt="Screenshot_2026-01-25_22_07_50"
src="https://github.com/user-attachments/assets/488dd0b0-3c17-4f45-b2d0-9339b8fd3409"
/>
where wclen_crash.c is
`
#include <wchar.h>
static_assert(wcslen("x") == 'x');
int main() {}
`
---------
Co-authored-by: Timm Baeder <tbaeder@redhat.com>
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