6 Commits

Author SHA1 Message Date
Iain Sandoe
6e4f870a21 re-land [C++20][Modules] Introduce an implementation module.
We need to be able to distinguish individual TUs from the same module in cases
where TU-local entities either need to be hidden (or, for some cases of ADL in
template instantiation, need to be detected as exposures).

This creates a module type for the implementation which implicitly imports its
primary module interface per C++20:
[module.unit/8] 'A module-declaration that contains neither an export-keyword
nor a module-partition implicitly imports the primary module interface unit of
the module as if by a module-import-declaration.

Implementation modules are never serialized (-emit-module-interface for an
implementation unit is diagnosed and rejected).

Differential Revision: https://reviews.llvm.org/D126959
2023-03-29 08:52:28 +05:30
Mitch Phillips
074f6fd61d Revert "[C++20][Modules] Introduce an implementation module."
This reverts commit c6e9823724ef6bdfee262289ee34d162db436af0.

Reason: Broke the ASan buildbots, see https://reviews.llvm.org/D126959
(the original phabricator review) for more info.
2023-03-27 05:01:53 -07:00
Iain Sandoe
c6e9823724 [C++20][Modules] Introduce an implementation module.
We need to be able to distinguish individual TUs from the same module in cases
where TU-local entities either need to be hidden (or, for some cases of ADL in
template instantiation, need to be detected as exposures).

This creates a module type for the implementation which implicitly imports its
primary module interface per C++20:
[module.unit/8] 'A module-declaration that contains neither an export-keyword
nor a module-partition implicitly imports the primary module interface unit of
the module as if by a module-import-declaration.

Implementation modules are never serialized (-emit-module-interface for an
implementation unit is diagnosed and rejected).

Differential Revision: https://reviews.llvm.org/D126959
2023-03-23 12:47:44 +00:00
Iain Sandoe
62a16d5e20 [C++2x][Modules] Amend module purview constant linkage [P2788R0].
This paper has been applied to the working draft and is believed to be
a DR against C++20, so that the patch here makes the change unconditionally.

for:
```
export module A;

const int mod_cst = 10;
```
Before the change, mod_cst would have internal linkage; after the change it
has module linkage.

Differential Revision: https://reviews.llvm.org/D145886
2023-03-19 16:25:56 +00:00
Chuanqi Xu
5783363681 [C++20] [Modules] Deprecate to load C++20 Modules eagerly
Close https://github.com/llvm/llvm-project/issues/60824

The form -fmodule-file=<path-to-BMI> will load modules eagerly and the
form -fmodule-file=<module-name>=<path-to-BMI> will load modules lazily.
The inconsistency adds many additional burdens to the implementations.
And the inconsistency looks not helpful and necessary neither. So I want
to deprecate the form -fmodule-file=<path-to-BMI> for named modules.
This is pretty helpful for us (the developers).

Does this change make any regression from the perspective of the users?

To be honest, yes. But I think such regression is acceptable. Here is
the example:

```
// M.cppm
export module M;
export int m = 5;

// N.cpp
// import M; // woops, we forgot to import M.
int n = m;
```

In the original version, the compiler can diagnose the users to import
`M` since the compiler have already imported M. But in the later style,
the compiler can only say "unknown identifier `m`".

But I think such regression doesn't make a deal since it only works if
the user put `-fmodule-file=M.pcm` in the command line. But how can the
user put `-fmodule-file=M.pcm` in the command line without `import M;`?
Especially currently such options are generated by build systems. And
the build systems will only generate the command line from the source
file.

So I think this change is pretty pretty helpful for developers and
almost innocent for users and we should accept this one.

I'll add the release notes and edit the document after we land this.

Differential Revision: https://reviews.llvm.org/D144707
2023-03-03 14:25:33 +08:00
Chuanqi Xu
d54888a3eb [Modules] Refactor modules-ts tests to use standard c++ modules
We're going to remove the support for modules-ts. But there are a lot of
tests which uses -fmodules-ts. We shouldn't remove them simply. This
patch refactor these tests to use standard c++ modules.
2023-02-16 14:05:16 +08:00