commit 15e93788c5fa4b098dde2dcc5ecc457cc020b689
author Martin Storsjo <martin@martin.st> Wed Sep 04 20:34:00 2019 +0000
committer Martin Storsjo <martin@martin.st> Wed Sep 04 20:34:00 2019 +0000
tree 813926a9580b03212e33a365007da98014a4ee44
parent 5542545ce7d176e066e0d7fe5b574295b4fa0372

[LLD] [COFF] Implement MinGW default manifest handling

In mingw environments, resources are normally compiled to resource
object files directly, instead of letting the linker convert them to
COFF format.

Since some time, GCC supports the notion of a default manifest object.
When invoking the linker, GCC looks for the default manifest object
file, and if found in the expected path, it is added to linker commands.

The default manifest is one that indicates support for the latest known
versions of windows, to implicitly unlock the modern behaviours of certain
APIs.

Not all mingw/gcc distributions include this file, but e.g. in msys2,
the default manifest object is distributed in a separate package (which
can be but might not always be installed).

This means that even if user projects only use one single resource
object file, the linker can end up with two resource object files,
and thus needs to support merging them.

The default manifest has a language id of zero, and GNU ld has got
logic for dropping a manifest with a zero language id, if there's
another manifest present with a nonzero language id. If there are
multiple manifests with a nonzero language id, the merging process
errors out.

Differential Revision: https://reviews.llvm.org/D66825

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@370974 91177308-0d34-0410-b5e6-96231b3b80d8