[analyzer] Admit that some copy/move constructors have more than one argument.

[NoQ]

Summary

Copy/move constructors may have additional default arguments and still be treated as normal copy/move constructors. Copy elision code expected this to not be a thing, for no particular reason. Remove the premature assertion.

Hopefully addresses the crash posted by @alexfh in http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20180702/233796.html

[NoQ]

Actually verify the CFG in the test.

lib/Analysis/CFG.cpp

void CFGBuilder::findConstructionContexts(
   };
 
   switch(Child->getStmtClass()) {
   case Stmt::CXXConstructExprClass:
   case Stmt::CXXTemporaryObjectExprClass: {
     // Support pre-C++17 copy elision AST.
     auto *CE = cast<CXXConstructExpr>(Child);
     if (BuildOpts.MarkElidedCXXConstructors && CE->isElidable()) {
-      assert(CE->getNumArgs() == 1);
       findConstructionContexts(withExtraLayer(CE), CE->getArg(0));
     }
 
     consumeConstructionContext(Layer, CE);
     break;
   }
   // FIXME: This, like the main visit, doesn't support CUDAKernelCallExpr.
   // FIXME: An isa<> would look much better but this whole switch is a

test/Analysis/cfg-rich-constructors.cpp

 // CXX17-NEXT:     3: [B1.2] (CXXConstructExpr, [B1.5], class argument_constructors::E)
 // CXX17-NEXT:     4: argument_constructors::E([B1.3]) (CXXFunctionalCastExpr, ConstructorConversion, class argument_constructors::E)
 // CXX17-NEXT:     5: argument_constructors::E e = argument_constructors::E(argument_constructors::D());
 // CXX17-NEXT:     6: ~argument_constructors::D() (Temporary object destructor)
 void passArgumentIntoAnotherConstructor() {
   E e = E(D());
 }
 } // end namespace argument_constructors
+
+namespace copy_elision_with_extra_arguments {
+class C {
+public:
+  C();
+  C(const C &c, int x = 0);
+};
+
+// CHECK: void testCopyElisionWhenCopyConstructorHasExtraArguments()
+// CHECK:        [B1]
+// CXX11-ELIDE-NEXT:     1: copy_elision_with_extra_arguments::C() (CXXConstructExpr, [B1.3], [B1.5], class copy_elision_with_extra_arguments::C)
+// CXX11-NOELIDE-NEXT:     1: copy_elision_with_extra_arguments::C() (CXXConstructExpr, [B1.3], class copy_elision_with_extra_arguments::C)
+// CXX11-NEXT:     2: [B1.1] (ImplicitCastExpr, NoOp, const class copy_elision_with_extra_arguments::C)
+// CXX11-NEXT:     3: [B1.2]
+// CXX11-NEXT:     4:
+// CXX11-NEXT:     5: [B1.3] (CXXConstructExpr, [B1.6], class copy_elision_with_extra_arguments::C)
+// CXX11-NEXT:     6: copy_elision_with_extra_arguments::C c = copy_elision_with_extra_arguments::C();
+// CXX17-NEXT:     1: copy_elision_with_extra_arguments::C() (CXXConstructExpr, [B1.2], class copy_elision_with_extra_arguments::C)
+// CXX17-NEXT:     2: copy_elision_with_extra_arguments::C c = copy_elision_with_extra_arguments::C();
+void testCopyElisionWhenCopyConstructorHasExtraArguments() {
+  C c = C();
+}
+} // namespace copy_elision_with_extra_arguments