-Warc-retain-cycles: warn at variable initialization as well as assignment.

Specifically, this should warn:

  __block block_t a = ^{ a(); };

Furthermore, this case which previously warned now does not, since the value
of 'b' is captured before the assignment occurs:

  block_t b; // not __block
  b = ^{ b(); };

(This will of course warn under -Wuninitialized, as before.)

<rdar://problem/11015883>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@163962 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 1 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index b46081dc99..0e6b5ec9a3 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -5299,7 +5299,8 @@ static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
     return false;
 
   owner.Variable = var;
-  owner.setLocsFrom(ref);
+  if (ref)
+    owner.setLocsFrom(ref);
   return true;
 }
 
@@ -5499,6 +5500,20 @@ void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
     diagnoseRetainCycle(*this, capturer, owner);
 }
 
+void Sema::checkRetainCycles(VarDecl *Var, Expr *Init) {
+  RetainCycleOwner Owner;
+  if (!considerVariable(Var, /*DeclRefExpr=*/0, Owner))
+    return;
+  
+  // Because we don't have an expression for the variable, we have to set the
+  // location explicitly here.
+  Owner.Loc = Var->getLocation();
+  Owner.Range = Var->getSourceRange();
+  
+  if (Expr *Capturer = findCapturingExpr(*this, Init, Owner))
+    diagnoseRetainCycle(*this, Capturer, Owner);
+}
+
 bool Sema::checkUnsafeAssigns(SourceLocation Loc,
                               QualType LHS, Expr *RHS) {
   Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();