https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108285
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:3456db4de8940235b303ca38a689353854c9239f commit r13-5152-g3456db4de8940235b303ca38a689353854c9239f Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Jan 13 18:23:57 2023 +0100 c++: Avoid some false positive -Wfloat-conversion warnings with extended precision [PR108285] On the following testcase trunk emits a false positive warning on ia32. convert_like_internal is there called with type of double and expr EXCESS_PRECISION_EXPR with float type with long double operand 2.L * (long double) x. Now, for the code generation we do the right thing, cp_convert to double from that 2.L * (long double) x, but we call even cp_convert_and_check with that and that emits the -Wfloat-conversion warning. Looking at what the C FE does in this case, it calls convert_and_check with the EXCESS_PRECISION_EXPR expression rather than its operand, and essentially uses the operand for code generation and EXCESS_PRECISION_EXPR itself for warnings. The following patch does that too for the C++ FE. 2023-01-13 Jakub Jelinek <ja...@redhat.com> PR c++/108285 * cvt.cc (cp_convert_and_check): For EXCESS_PRECISION_EXPR use its operand except that for warning purposes use the original EXCESS_PRECISION_EXPR. * call.cc (convert_like_internal): Only look through EXCESS_PRECISION_EXPR when calling cp_convert, not when calling cp_convert_and_check. * g++.dg/warn/pr108285.C: New test.
