[Bug c++/98944] New: [modules] Failed to read compiled module with a non-exported partition.

[Bug c++/98944] New: [modules] Failed to read compiled module with a non-exported partition.

[iains at gcc dot gnu.org]

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

            Bug ID: 98944
           Summary: [modules] Failed to read compiled module with a
                    non-exported partition.
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: iains at gcc dot gnu.org
  Target Milestone: ---

Example 1 from the std:

tu1:
export module A;
export import :Foo;
export int baz();

tu2:
export module A:Foo;
import :Internals;
export int foo() { return 2 * (bar() + 1); }

tu3:
module A:Internals;
int bar();

tu4:
module A;
import :Internals;
int bar() { return baz() - 10; }
int baz() { return 30; }

====

g++ -std=c++20 -fmodules-ts /source/test/module/mu-tu-3.cxx -S
g++ -std=c++20 -fmodules-ts /source/test/module/mu-tu-2.cxx -S
g++ -std=c++20 -fmodules-ts /source/test/module/mu-tu-1.cxx -S

ls gcm.cache/
A-Foo.gcm       A-Internals.gcm A.gcm

g++ -std=c++20 -fmodules-ts /source/test/module/mu-tu-4.cxx -S
A: error: failed to read compiled module: Bad file data
A: note: compiled module file is ‘gcm.cache/A.gcm’
...

[Bug c++/98944] [modules] Failed to read compiled module with a non-exported partition.

[StevenSun2021 at hotmail dot com]

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

Steven Sun <StevenSun2021 at hotmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |StevenSun2021 at hotmail dot com

--- Comment #1 from Steven Sun <StevenSun2021 at hotmail dot com> ---
I met the same problem. 

-------------------------------------------------------------------------

Three days ago, I pull from the repository and then compile the gnu c++
compiler in the devel/c++-modules branch.

system: ubuntu-20.04 x86_64
configured with: --disable-multilib

I took the same exaple as you, which is in the final working draft n4861
[modules.unit].

I think the compile order should be tu3 tu2 tu1 tu4, because the compiler tells
me I cannot import before build. So I compile it as 


g++ -fmodules-ts -std=c++20 -c 3.cc -o 3.o
g++ -fmodules-ts -std=c++20 -c 2.cc -o 2.o
g++ -fmodules-ts -std=c++20 -c 1.cc -o 1.o
g++ -fmodules-ts -std=c++20 -c 4.cc -o 4.o


The compiling for 4.cc got an error
------------------------------------------------------
In module imported at 4.cc:1:1:
A: error: failed to read compiled module: Bad file data
A: note: compiled module file is ‘gcm.cache/A.gcm’
A: fatal error: returning to the gate for a mechanical issue
compilation terminated.
------------------------------------------------------

Then I took a peek into the gcm.cache/A.gcm, using readelf. Found that there's
already a section header named bar.

So I removed the line `import :Internals;` in 4.cc and it compiles.

Anyway, I don't know if that is a bug. Maybe the standard is different from the
final working draft. I am not sure.

[Bug c++/98944] [modules] Failed to read compiled module with a non-exported partition.

[nathan at gcc dot gnu.org]

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

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |nathan at gcc dot gnu.org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
   Last reconfirmed|2021-02-02 00:00:00         |2021-02-09

[Bug c++/98944] [modules] Failed to read compiled module with a non-exported partition.

[cvs-commit at gcc dot gnu.org]

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

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathan Sidwell <nathan@gcc.gnu.org>:

https://gcc.gnu.org/g:92941cea2f05a8cf79fc71aa39fa948dcfb82d7a

commit r11-7150-g92941cea2f05a8cf79fc71aa39fa948dcfb82d7a
Author: Nathan Sidwell <nathan@acm.org>
Date:   Tue Feb 9 08:11:58 2021 -0800

    c++: Fix indirect partitions [PR 98944]

    The most recent reimplementation of module loading initialization
    changed the behaviour of setting an import's location, and broke some
    partition handling.

            PR c++/98944
            gcc/cp/
            * module.cc (module_state::is_rooted): Rename to ...
            (module_state::has_location): ... here.  Adjust callers.
            (module_state::read_partitions): Adjust validity check.
            Don't overwrite a known location.
            gcc/testsuite/
            * g++.dg/modules/pr98944_a.C: New.
            * g++.dg/modules/pr98944_b.C: New.
            * g++.dg/modules/pr98944_c.C: New.
            * g++.dg/modules/pr98944_d.C: New.

[Bug c++/98944] [modules] Failed to read compiled module with a non-exported partition.

[nathan at gcc dot gnu.org]

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

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #3 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
92941cea2f0 2021-02-09 | c++: Fix indirect partitions [PR 98944]