[CFG] [analyzer] pr41142: C++17: Skip transparent InitListExprs in co…

…nstructors.

When searching for construction contexts, i.e. figuring out which statements
define the object that is constructed by each construct-expression, ignore
transparent init-list expressions because they don't add anything to the
context. This allows the Static Analyzer to model construction, destruction,
materialization, lifetime extension correctly in more cases. Also fixes
a crash caused by incorrectly evaluating initial values of variables
initialized with such expressions.

Differential Revision: https://reviews.llvm.org/D59573

llvm-svn: 356634

clang/lib/Analysis/CFG.cpp

@@ -1378,6 +1378,15 @@ void CFGBuilder::findConstructionContexts(
     findConstructionContexts(Layer, CO->getRHS());
     break;
   }
+  case Stmt::InitListExprClass: {
+    auto *ILE = cast<InitListExpr>(Child);
+    if (ILE->isTransparent()) {
+      findConstructionContexts(Layer, ILE->getInit(0));
+      break;
+    }
+    // TODO: Handle other cases. For now, fail to find construction contexts.
+    break;
+  }
   default:
     break;
   }

clang/test/Analysis/cfg-rich-constructors.cpp

@@ -1043,3 +1043,23 @@ void testCrashOnVariadicArgument() {
   C c(variadic(0 ? c : 0)); // no-crash
 }
 } // namespace variadic_function_arguments
+
+// CHECK: void testTransparentInitListExprs()
+// CHECK:        [B1]
+// CHECK-NEXT:     1: getC
+// CHECK-NEXT:     2: [B1.1] (ImplicitCastExpr, FunctionToPointerDecay, class transparent_init_list_exprs::C (*)(void))
+// CXX11-ELIDE-NEXT:     3: [B1.2]() (CXXRecordTypedCall, [B1.4], [B1.5])
+// CXX11-NOELIDE-NEXT:     3: [B1.2]() (CXXRecordTypedCall, [B1.4])
+// CXX11-NEXT:     4: [B1.3]
+// CXX11-NEXT:     5: {[B1.4]} (CXXConstructExpr, [B1.6], class transparent_init_list_exprs::C)
+// CXX11-NEXT:     6: transparent_init_list_exprs::C c{getC()};
+// CXX17-NEXT:     3: [B1.2]() (CXXRecordTypedCall, [B1.5])
+// CXX17-NEXT:     4: {[B1.3]}
+// CXX17-NEXT:     5: transparent_init_list_exprs::C c{getC()};
+namespace transparent_init_list_exprs {
+class C {};
+C getC();
+void testTransparentInitListExprs() {
+  C c{getC()};
+}
+} // namespace transparent_init_list_exprs

clang/test/Analysis/initializer.cpp

@@ -242,4 +242,22 @@ void foo() {
   B &&bcr = C({{}}); // no-crash
 #endif
 }
+} // namespace CXX17_aggregate_construction
+
+namespace CXX17_transparent_init_list_exprs {
+class A {};
+
+class B: private A {};
+
+B boo();
+void foo1() {
+  B b { boo() }; // no-crash
+}
+
+class C: virtual public A {};
+
+C coo();
+void foo2() {
+  C c { coo() }; // no-crash
 }
+} // namespace CXX17_transparent_init_list_exprs