When declaring an entity in the "purview" of a module, it's never a
redeclaration of an entity in the purview of a default module or in no module
("in the global module"). Don't consider those other declarations as possible
redeclaration targets if they're not visible, and reject any cases where we
pick a prior visible declaration that violates this rule.
This reinstates r315251 and r315256, reverted in r315309 and r315308
respectively, tweaked to avoid triggering a linkage calculation when declaring
implicit special members (this exposed our pre-existing issue with typedef
names for linkage changing the linkage of types whose linkage has already been
computed and cached in more cases). A testcase for that regression has been
added in r315366.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@315379 91177308-0d34-0410-b5e6-96231b3b80d8
This works around a language issue where adding a typedef name for linkage
purposes changes the linkage of an already-defined class after it becomes
complete.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@315256 91177308-0d34-0410-b5e6-96231b3b80d8
Richard Smith