[basic.link]/p10:
> If two declarations of an entity are attached to different modules,
> the program is ill-formed
But we only implemented the check for ODR. In this patch, we tried to
diagnose the redeclarations from different modules.
Close https://github.com/llvm/llvm-project/issues/79240.
See the linked issue for details. Given the frequency of issue reporting
about false positive ODR checks (I received private issue reports too),
I'd like to backport this to 18.x too.
Close https://github.com/llvm/llvm-project/issues/61064.
The root cause of the issue is that we will deserilize some declarations
eagerly when reading the BMI. However, many declarations in the BMI are
not necessary for the importer. So it wastes a lot of time.
The new commit handles the MSVC's extension #pragma comment and #pragma
detect_mismatch to follow MSVC's behavior. See pr61783 for details.
This reverts commit af86957cbbffd3dfff3c6750ebddf118aebd0069.
Close https://github.com/llvm/llvm-project/issues/61733.
Previously I banned the eagerly loading for declarations from named
modules to speedup the process of reading modules. But I didn't think
about special decls like PragmaCommentDecl and PragmaDetectMismatchDecl.
So here is the issue https://github.com/llvm/llvm-project/issues/61733.
Note that the current behavior is still incorrect. Given:
```
// mod.cppm
module;
export module mod;
```
and
```
// user.cpp
import mod;
```
Now the IR of `user.cpp` will contain the metadata '!0 =
!{!"msvcprt.lib"}' incorrectly. The root cause of the problem is that
`EagerlyDeserializedDecls` is designed for headers and it didn't take
care for named modules. We need to redesign a new mechanism for named
modules.
Close https://github.com/llvm/llvm-project/issues/61064.
The root cause of the issue is that we will deserilize some declarations
eagerly when reading the BMI. However, many declarations in the BMI are
not necessary for the importer. So it wastes a lot of time.
