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From: "overlord624 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/101126] New: Enabling modules suppresses creation of
 precompiled headers
Date: Fri, 18 Jun 2021 15:41:04 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101126

            Bug ID: 101126
           Summary: Enabling modules suppresses creation of precompiled
                    headers
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: overlord624 at gmail dot com
  Target Milestone: ---

The output of a precompiled header is suppressed if modules are enabled via
-fmodules-ts. This can be reproduced with the following invocation using any
valid input:
g++-11 -x c++-header -std=3Dc++20 -fmodules-ts -o header.hpp.gch header.hpp

As described in the manual, -fmodules-ts implicitly sets -fmodule-header wh=
en
the input is a header file which results in the creation of a compiled head=
er
unit in the module cache and causes the output parameter to be silently ign=
ored
as a side effect.

-----
$ g++-11 -v
Using built-in specs.
COLLECT_GCC=3Dg++-11
COLLECT_LTO_WRAPPER=3D/media/extra/libexec/gcc/x86_64-pc-linux-gnu/11.0.1/l=
to-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /media/extra/sources/gcc/configure --host=3Dx86_64-pc-linu=
x-gnu
--prefix=3D/media/extra --disable-multilib --enable-threads --enable-tls
--enable-languages=3Dc,c++ --disable-nls
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.0.1 20210402 (experimental) (GCC)=