[all-commits] [llvm/llvm-project] 328a6e: Force visibility of llvm::Any to external

[Tom Stellard via All-commits]

  Branch: refs/heads/release/12.x
  Home:   https://github.com/llvm/llvm-project
  Commit: 328a6ec955327c6d56b6bc3478c723dd3cd468ef
      https://github.com/llvm/llvm-project/commit/328a6ec955327c6d56b6bc3478c723dd3cd468ef
  Author: serge-sans-paille <sguelton at redhat.com>
  Date:   2021-05-24 (Mon, 24 May 2021)

  Changed paths:
    M llvm/include/llvm/ADT/Any.h

  Log Message:
  -----------
  Force visibility of llvm::Any to external

llvm::Any::TypeId::Id relies on the uniqueness of the address of a static
variable defined in a template function. hidden visibility implies vague linkage
for that variable, which does not guarantee the uniqueness of the address across
a binary and a shared library. This totally breaks the implementation of
llvm::Any.

Ideally, setting visibility to llvm::Any::TypeId::Id should be enough,
unfortunately this doesn't work as expected and we lack time (before 12.0.1
release) to understand why setting the visibility to llvm::Any does work.

See https://gcc.gnu.org/wiki/Visibility and
https://gcc.gnu.org/onlinedocs/gcc/Vague-Linkage.html
for more information on that topic.

Differential Revision: https://reviews.llvm.org/D101972

(cherry picked from commit 3d3abc22b3ef189813a3b9061c2a90ba86a32f44)