https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115797
Bug ID: 115797
Summary: [15 Regression] 'extern "C" { #include <math.h> }'
fails with 'error: template with C linkage' since
r15-1857-gde19b516edbf91
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
Target Milestone: ---
Noticed on jemalloc-5.3.0 which tries to defensively wrap all system headers
into extern "C":
https://github.com/jemalloc/jemalloc/blob/dev/test/include/test/jemalloc_test.h.in#L5
// $ cat /tmp/a.cc
extern "C" {
#include <math.h>
}
Since r15-1857-gde19b516edbf91 "libstdc++: Use memchr to optimize std::find
[PR88545]" gcc-15 started breaking it (cmath pulls in <type_traits>) as:
$ __i__/bin/g++ -c /tmp/a.cc
In file included from
/tmp/gb/__i__/include/c++/15.0.0/bits/cpp_type_traits.h:40,
from /tmp/gb/__i__/include/c++/15.0.0/cmath:44,
from /tmp/gb/__i__/include/c++/15.0.0/math.h:36,
from /tmp/a.cc:2:
/tmp/gb/__i__/include/c++/15.0.0/type_traits:69:3: error: template with C
linkage
69 | template<typename _Tp>
| ^~~~~~~~
...
Should it compile? It feels like it should and a few `extern "C++"` are missing
somewhere.
Target: x86_64-pc-linux-gnu
