https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92717
Bug ID: 92717
Summary: precompiled headers non-deterministic
Product: gcc
Version: 9.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gnu.org at mrks dot info
Target Milestone: ---
I found that introducing precompiled headers to my project causes ccache
lookups to fail. I tracked it down to the gcc output not being deterministic:
# /usr/bin/c++ -x c++-header -include test.hxx -o test.hxx.gch -c test.hxx.cxx
&& md5sum test.hxx.gch
3a0efb998351939f4ed8efcfce1c0015 test.hxx.gch
# /usr/bin/c++ -x c++-header -include test.hxx -o test.hxx.gch -c test.hxx.cxx
&& md5sum test.hxx.gch
d295cbe3613100e6d989e62e3aafad6c test.hxx.gch
Both test.hxx and test.hxx.cxx are empty. The used gcc version is
9.2.1-9ubuntu2.
With clang (clang++ -cc1 test.hxx -emit-pch -o test.hxx.pch), the hashes match.
When compiling with save-temps, the ii and s files match.
As builds of regular C(++) files are deterministic (as expected), I suspect
that this might be a bug.
