Thread safety analysis: Consider global variables in scope

Instead of just mutex members we also consider mutex globals.
Unsurprisingly they are always in scope. Now the paper [1] says that

> The scope of a class member is assumed to be its enclosing class,
> while the scope of a global variable is the translation unit in
> which it is defined.

But I don't think we should limit this to TUs where a definition is
available - a declaration is enough to acquire the mutex, and if a mutex
is really limited in scope to a translation unit, it should probably be
only declared there.

[1] https://static.googleusercontent.com/media/research.google.com/en/us/pubs/archive/42958.pdf

Fixes PR46354.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D84604

1 files changed, 11 insertions, 2 deletions

diff --git a/clang/lib/Analysis/ThreadSafety.cpp b/clang/lib/Analysis/ThreadSafety.cpp
index 64e0da9..1d4aaba 100644
--- a/clang/lib/Analysis/ThreadSafety.cpp
+++ b/clang/lib/Analysis/ThreadSafety.cpp
@@ -1266,13 +1266,22 @@ ClassifyDiagnostic(const AttrTy *A) {
 }
 
 bool ThreadSafetyAnalyzer::inCurrentScope(const CapabilityExpr &CapE) {
-  if (!CurrentMethod)
+  const threadSafety::til::SExpr *SExp = CapE.sexpr();
+  assert(SExp && "Null expressions should be ignored");
+
+  // Global variables are always in scope.
+  if (isa<til::LiteralPtr>(SExp))
+    return true;
+
+  // Members are in scope from methods of the same class.
+  if (const auto *P = dyn_cast<til::Project>(SExp)) {
+    if (!CurrentMethod)
       return false;
-  if (const auto *P = dyn_cast_or_null<til::Project>(CapE.sexpr())) {
     const auto *VD = P->clangDecl();
     if (VD)
       return VD->getDeclContext() == CurrentMethod->getDeclContext();
   }
+
   return false;
 }