[Bug c++/106009] New: [modules] internal compiler error: in mark_by_value, at cp/module.cc:4775

[Bug c++/106009] New: [modules] internal compiler error: in mark_by_value, at cp/module.cc:4775

[overlord624 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106009

            Bug ID: 106009
           Summary: [modules] internal compiler error: in mark_by_value,
                    at cp/module.cc:4775
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: overlord624 at gmail dot com
  Target Milestone: ---

Created attachment 53158
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53158&action=edit
output with -freport-bug

Trying to compile the spdlog library to a header unit causes an internal
compiler error. Adding -save-temps to the parameters causes the same error, but
the compiler claims the error is non-reproducible. No errors occur when the
same header is included in the global module fragment of a regular module.

$ g++-exp -freport-bug -fmodules-ts -std=c++20 -Wall -Wextra -pedantic
-DSPDLOG_COMPILED_LIB -x c++-system-header spdlog/spdlog.h
/usr/include/spdlog/spdlog.h: internal compiler error: in mark_by_value, at
cp/module.cc:4775
0x7112a2 trees_out::mark_by_value(tree_node*)
        /media/extra/sources/gcc/gcc/cp/module.cc:4775
0xabe961 trees_out::mark_declaration(tree_node*, bool)
        /media/extra/sources/gcc/gcc/cp/module.cc:12245
0xabebd9 trees_out::mark_class_def(tree_node*)
        /media/extra/sources/gcc/gcc/cp/module.cc:11744
0xac859d depset::hash::find_dependencies(module_state*)
        /media/extra/sources/gcc/gcc/cp/module.cc:13126
0xac8cc0 module_state::write_begin(elf_out*, cpp_reader*, module_state_config&,
unsigned int&)
        /media/extra/sources/gcc/gcc/cp/module.cc:17640
0xac9f84 finish_module_processing(cpp_reader*)
        /media/extra/sources/gcc/gcc/cp/module.cc:19962
0xa58c85 c_parse_final_cleanups()
        /media/extra/sources/gcc/gcc/cp/decl2.cc:5156
0xc7ab60 c_common_parse_file()
        /media/extra/sources/gcc/gcc/c-family/c-opts.cc:1253
Please submit a full bug report, with preprocessed source.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Preprocessed source stored into /tmp/cc4TWK1u.out file, please attach this to
your bugreport.

$ g++-exp -v
Using built-in specs.
COLLECT_GCC=g++-exp
COLLECT_LTO_WRAPPER=/media/extra/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /media/extra/sources/gcc/configure --host=x86_64-pc-linux-gnu
--prefix=/media/extra --disable-multilib --enable-threads --enable-tls
--enable-languages=c,c++ --disable-nls
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.0.0 20220616 (experimental) (GCC)

[Bug c++/106009] [modules] internal compiler error: in mark_by_value, at cp/module.cc:4775

[overlord624 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106009

--- Comment #1 from John Smith <overlord624 at gmail dot com> ---
Created attachment 53159
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53159&action=edit
preprocessed with -save-temps

[Bug c++/106009] [modules] internal compiler error: in import_entity_index with templated local enum in header unit

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106009

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[modules] internal compiler |[modules] internal compiler
                   |error: in mark_by_value, at |error: in
                   |cp/module.cc:4775           |import_entity_index with
                   |                            |templated local enum in
                   |                            |header unit
                 CC|                            |ppalka at gcc dot gnu.org

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
The mark_by_value ICE is fixed on trunk by r13-3166-gf7f4628054358a I suspect. 
But we now crash from import_entity_index instead.  Reduced reproducer:

$ cat 106009.H
template<class T>
void format_decimal(T) {
  enum blah {};
}

inline void write() {
  format_decimal(0);
}

$ g++ -fmodule-header 106009.H
106009.H: internal compiler error: in import_entity_index, at cp/module.cc:4071

[Bug c++/106009] [modules] internal compiler error: in import_entity_index with templated local enum in header unit

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106009

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-02-13
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |ice-checking,
                   |                            |ice-on-valid-code

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
FWIW also crash from import_entity_index if we use an undefined local struct:

template<class T>
void format_decimal(T) {
  struct blah;
}

but not if we define it:

template<class T>
void format_decimal(T) {
  struct blah {};
}

[Bug c++/106009] [modules] internal compiler error: in import_entity_index with templated local enum in header unit

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106009

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
             Status|NEW                         |ASSIGNED
   Target Milestone|---                         |14.0

[Bug c++/106009] [modules] internal compiler error: in import_entity_index with templated local enum in header unit

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106009

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:574fd1f17f100c7c355ad26bc525ab5a3386bb2d

commit r14-9268-g574fd1f17f100c7c355ad26bc525ab5a3386bb2d
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Mar 1 17:24:15 2024 -0500

    c++/modules: depending local enums [PR104919, PR106009]

    For local enums defined in a non-template function or a function template
    instantiation it seems we neglect to make the function depend on the enum
    definition (which modules considers logically separate), which ultimately
    causes the enum definition to not be properly streamed before uses
    within the function definition are streamed.

    The code responsible for noting such dependencies is

    gcc/cp/module.cc
    @@ -8784,17 +8784,6 @@ trees_out::decl_node (tree decl, walk_kind ref)
       depset *dep = NULL;
       if (streaming_p ())
         dep = dep_hash->find_dependency (decl);
    !  else if (TREE_CODE (ctx) != FUNCTION_DECL
    !          || TREE_CODE (decl) == TEMPLATE_DECL
    !          || (dep_hash->sneakoscope && DECL_IMPLICIT_TYPEDEF_P (decl))
    !          || (DECL_LANG_SPECIFIC (decl)
    !              && DECL_MODULE_IMPORT_P (decl)))
    !    {
    !      auto kind = (TREE_CODE (decl) == NAMESPACE_DECL
    !                  && !DECL_NAMESPACE_ALIAS (decl)
    !                  ? depset::EK_NAMESPACE : depset::EK_DECL);
    !      dep = dep_hash->add_dependency (decl, kind);
    !    }

       if (!dep)
         {

    and the condition there notably excludes local TYPE_DECLs from a
    non-template-pattern function (when streaming a template pattern
    we'll see be dealing with the corresponding TEMPLATE_DECL of the
    local TYPE_DECL here, so we'll add the dependency).

    Local classes on the other hand seem to work properly, but perhaps by
    accident: with a local class we end up making the function depend on the
    injected-class-name of the local class rather than the local class as a
    whole because the injected-class-name satisfies the criteria (since its
    context is the local class, not the function).

    The 'sneakoscope' flag is set when walking a function declaration and
    its purpose seems to be to catch a local type that escapes the function
    via a deduced return type (so called voldemort types) and note a
    dependency on them.  But there seems to be no reason to restrict this
    behavior to voldemort types, and indeed consistently noting the dependency
    for all local types fixes these PRs (almost).  So this patch gets rid of
    this flag and enables the dependency tracking unconditionally.

    This was nearly enough to make things work, except we now ran into
    issues with the local TYPE_/CONST_DECL copies from the pre-gimplified
    version of a constexpr function body during streaming.  Rather than
    making modules cope with this, it occurred to me that we don't need to
    make copies of local types when saving the pre-gimplified body (and when
    making further copies thereof); only VAR_DECLs etc need to be copied
    (so that we don't conflate local variables from different recursive
    calls to the same function during constexpr evaluation).  So this patch
    adjusts copy_fn accordingly.

            PR c++/104919
            PR c++/106009

    gcc/cp/ChangeLog:

            * module.cc (depset::hash::sneakoscope): Remove.
            (trees_out::decl_node): Always add a dependency on a local type.
            (depset::hash::find_dependencies): Remove sneakoscope stuff.

    gcc/ChangeLog:

            * tree-inline.cc (remap_decl): Handle copy_decl returning the
            original decl.
            (remap_decls): Handle remap_decl returning the original decl.
            (copy_fn): Adjust copy_decl callback to skip TYPE_DECL and
            CONST_DECL.

    gcc/testsuite/ChangeLog:

            * g++.dg/modules/tdef-7.h: Remove outdated comment.
            * g++.dg/modules/tdef-7_b.C: Don't expect two TYPE_DECLs.
            * g++.dg/modules/enum-13_a.C: New test.
            * g++.dg/modules/enum-13_b.C: New test.

[Bug c++/106009] [modules] internal compiler error: in import_entity_index with templated local enum in header unit

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106009

Patrick Palka <ppalka at gcc dot gnu.org> changed:

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

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 14.