https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99682
Bug ID: 99682
Summary: [modules] Module implementation unit is unable to
indirectly import its corresponding interface unit
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ensadc at mailnesia dot com
Target Milestone: ---
$ cat src/foo.cpp
export module foo;
$ cat src/bar.cpp
export module bar;
import foo;
$ cat src/foo-impl.cpp
module foo;
import bar;
$ g++ -fmodules-ts -c src/foo.cpp
$ g++ -fmodules-ts -c src/bar.cpp
$ g++ -fmodules-ts -c src/foo-impl.cpp
In module imported at src/foo-impl.cpp:2:1:
bar: error: cannot import module in its own purview
In module imported at src/foo-impl.cpp:1:1:
foo: note: module ‘foo’ declared here
In module imported at src/foo-impl.cpp:2:1:
bar: error: failed to read compiled module: Bad import dependency
bar: note: compiled module file is ‘gcm.cache/bar.gcm’
bar: fatal error: returning to the gate for a mechanical issue
compilation terminated.
====
AFAIK, although a module implementation unit cannot *directly* imports its
module interface unit (http://eel.is/c++draft/module.import#9 ), *indirect*
import should not be prohibited (and should probably be a no-op, because the
primary module interface unit has been imported by `module foo;`).
MSVC compiles this test case without any errors.
