[Bug c++/102525] New: error: failed to read compiled module: Bad file data when trying to use modules possible 98944 regression

[e9leyland at outlook dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102525

            Bug ID: 102525
           Summary: error: failed to read compiled module: Bad file data
                    when trying to use modules possible 98944 regression
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: e9leyland at outlook dot com
  Target Milestone: ---

I create the precompiled headers for the system headers, one by one

$ g++ -fmodules-ts -std=c++20 -x c++-system-header concepts
$ g++ -fmodules-ts -std=c++20 -x c++-system-header limits
$ g++ -fmodules-ts -std=c++20 -x c++-system-header iostream

I gathered up the required system headers into Reverse

$ cat Reverse
import <concepts>;
import <limits>;
import <iostream>;

$  g++ -fmodules-ts -std=c++20 -x c++-header Reverse

$ ls gcm.cache/,
Reverse.gcm

I try to import the module header

$ head Reverse.cpp
import <Reverse>;

$ make
g++ -fmodules-ts -std=c++20 -I./  -o Reverseexec Reverse.cpp
In module imported at Reverse.cpp:4:1:
./Reverse: error: failed to read compiled module: Bad file data
./Reverse: note: compiled module file is ‘gcm.cache/,/Reverse.gcm’
./Reverse: fatal error: returning to the gate for a mechanical issue
compilation terminated.
make: *** [Makefile:2: Reverseexec] Error 1

I change the imports in Reverse.cpp and it compiles

$ head Reverse.cpp
import <concepts>;
import <limits>;
import <iostream>;

$ make
g++ -fmodules-ts -std=c++20 -o Reverse Reverse.cpp

I found what seems to be a related bug.

[Bug c++/98944] [modules] Failed to read compiled module with a non-exported
partition.
StevenSun2021 at hotmail dot com via Gcc-bugs Mon, 08 Feb 2021 22:49:45 -0800

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98944

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/11/lto-wrapper.exe
Target: x86_64-pc-cygwin
Configured with: /mnt/share/cygpkgs/gcc/gcc.x86_64/src/gcc-11.2.0/configure
--srcdir=/mnt/share/cygpkgs/gcc/gcc.x86_64/src/gcc-11.2.0 --prefix=/usr
--exec-prefix=/usr --localstatedir=/var --sysconfdir=/etc
--docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C
--build=x86_64-pc-cygwin --host=x86_64-pc-cygwin --target=x86_64-pc-cygwin
--without-libiconv-prefix --without-libintl-prefix --libexecdir=/usr/lib
--with-gcc-major-version-only --enable-shared --enable-shared-libgcc
--enable-static --enable-version-specific-runtime-libs --enable-bootstrap
--enable-__cxa_atexit --with-dwarf2 --with-tune=generic --disable-bootstrap
--enable-languages=c,c++,fortran,lto,objc,obj-c++,jit --enable-graphite
--enable-threads=posix --enable-libatomic --enable-libgomp --enable-libquadmath
--enable-libquadmath-support --disable-libssp --enable-libada --disable-symvers
--with-gnu-ld --with-gnu-as --with-cloog-include=/usr/include/cloog-isl
--without-libiconv-prefix --without-libintl-prefix --with-system-zlib
--enable-linker-build-id --with-default-libstdcxx-abi=gcc4-compatible
--enable-libstdcxx-filesystem-ts
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.2.0 (GCC)

What am I doing incorrectly? Why am I getting this error,

g++ -fmodules-ts -std=c++20 -I./  -o Reverseexec Reverse.cpp
In module imported at Reverse.cpp:4:1:
./Reverse: error: failed to read compiled module: Bad file data
./Reverse: note: compiled module file is ‘gcm.cache/,/Reverse.gcm’
./Reverse: fatal error: returning to the gate for a mechanical issue
compilation terminated.
make: *** [Makefile:2: Reverseexec] Error 1