The modules side of r299226, which serializes #pragma pack state,
doesn't work well.
The main purpose was to make -include and -include-pch match semantics
(the PCH side). We also started serializing #pragma pack in PCMs, in
the hopes of making modules and non-modules builds more consistent. But
consider:
$ cat a.h
$ cat b.h
#pragma pack(push, 2)
$ cat module.modulemap
module M {
module a { header "a.h" }
module b { header "b.h" }
}
$ cat t.cpp
#include "a.h"
#pragma pack(show)
As of r299226, the #pragma pack(show) gives "2", even though we've only
included "a.h".
- With -fmodules-local-submodule-visibility, this is clearly wrong. We
should get the default state (8 on x86_64).
- Without -fmodules-local-submodule-visibility, this kind of matches how
other things work (as if include-the-whole-module), but it's still
really terrible, and it doesn't actually make modules and non-modules
builds more consistent.
This commit disables the serialization for modules, essentially a
partial revert of r299226.
Going forward:
1. Having this #pragma pack stuff escape is terrible design (or, more
often, a horrible bug). We should prioritize adding warnings (maybe
-Werror by default?).
2. If we eventually reintroduce this for modules, it should only apply
to -fmodules-local-submodule-visibility, and it should be tracked on
a per-submodule basis.
llvm-svn: 300380
Duncan P. N. Exon Smith