r340975 - [CFG] [analyzer] Disable argument construction contexts for variadic functions.

[Artem Dergachev via cfe-commits]

Author: dergachev
Date: Wed Aug 29 14:50:52 2018
New Revision: 340975

URL: http://llvm.org/viewvc/llvm-project?rev=340975&view=rev
Log:
[CFG] [analyzer] Disable argument construction contexts for variadic functions.

The analyzer doesn't make use of them anyway and they seem to have
pretty weird AST from time to time, so let's just skip them for now.

Fixes pr37769.

Differential Revision: https://reviews.llvm.org/D50824

Modified:
    cfe/trunk/lib/Analysis/CFG.cpp
    cfe/trunk/test/Analysis/cfg-rich-constructors.cpp

Modified: cfe/trunk/lib/Analysis/CFG.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/CFG.cpp?rev=340975&r1=340974&r2=340975&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/CFG.cpp (original)
+++ cfe/trunk/lib/Analysis/CFG.cpp Wed Aug 29 14:50:52 2018
@@ -2421,8 +2421,6 @@ CFGBlock *CFGBuilder::VisitCallExpr(Call
     if (!boundType.isNull()) calleeType = boundType;
   }
 
-  findConstructionContextsForArguments(C);
-
   // If this is a call to a no-return function, this stops the block here.
   bool NoReturn = getFunctionExtInfo(*calleeType).getNoReturn();
 
@@ -2439,6 +2437,13 @@ CFGBlock *CFGBuilder::VisitCallExpr(Call
   bool OmitArguments = false;
 
   if (FunctionDecl *FD = C->getDirectCallee()) {
+    // TODO: Support construction contexts for variadic function arguments.
+    // These are a bit problematic and not very useful because passing
+    // C++ objects as C-style variadic arguments doesn't work in general
+    // (see [expr.call]).
+    if (!FD->isVariadic())
+      findConstructionContextsForArguments(C);
+
     if (FD->isNoReturn() || C->isBuiltinAssumeFalse(*Context))
       NoReturn = true;
     if (FD->hasAttr<NoThrowAttr>())

Modified: cfe/trunk/test/Analysis/cfg-rich-constructors.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/cfg-rich-constructors.cpp?rev=340975&r1=340974&r2=340975&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/cfg-rich-constructors.cpp (original)
+++ cfe/trunk/test/Analysis/cfg-rich-constructors.cpp Wed Aug 29 14:50:52 2018
@@ -1028,3 +1028,18 @@ void testOperators() {
   C(1) + C(2);
 }
 } // namespace operators
+
+namespace variadic_function_arguments {
+class C {
+ public:
+  C(int);
+};
+
+int variadic(...);
+
+// This code is quite exotic, so let's not test the CFG for it,
+// but only make sure we don't crash.
+void testCrashOnVariadicArgument() {
+  C c(variadic(0 ? c : 0)); // no-crash
+}
+} // namespace variadic_function_arguments