[analyzer] Fix a crash when doing RVO from within blocks.

When looking for the location context of the call site, unwrap block invocation
contexts because they are attached to the current AnalysisDeclContext
while what we need is the previous AnalysisDeclContext.

Differential Revision: https://reviews.llvm.org/D61545

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@360202 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit f587801)

lib/StaticAnalyzer/Core/ExprEngineCXX.cpp

@@ -197,6 +197,12 @@ std::pair<ProgramStateRef, SVal> ExprEngine::prepareForObjectConstruction(
           // able to find construction context at all.
           break;
         }
+        if (isa<BlockInvocationContext>(CallerLCtx)) {
+          // Unwrap block invocation contexts. They're mostly part of
+          // the current stack frame.
+          CallerLCtx = CallerLCtx->getParent();
+          assert(!isa<BlockInvocationContext>(CallerLCtx));
+        }
         return prepareForObjectConstruction(
             cast<Expr>(SFC->getCallSite()), State, CallerLCtx,
             RTC->getConstructionContext(), CallOpts);

test/Analysis/copy-elision.mm

@@ -0,0 +1,18 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core -fblocks -verify %s
+
+// expected-no-diagnostics
+
+namespace block_rvo_crash {
+struct A {};
+
+A getA();
+void use(A a) {}
+
+void foo() {
+  // This used to crash when finding construction context for getA()
+  // (which is use()'s argument due to RVO).
+  use(^{
+    return getA();  // no-crash
+  }());
+}
+} // namespace block_rvo_crash