[PATCH] D50824: [CFG] [analyzer] pr37769: Disable argument construction contexts for variadic functions.

[Artem Dergachev via Phabricator via cfe-commits]

NoQ created this revision.
NoQ added reviewers: dcoughlin, xazax.hun, a.sidorin, george.karpenkov, szepet, rnkovacs.
Herald added subscribers: cfe-commits, Szelethus, mikhail.ramalho, baloghadamsoftware.

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

Fixes the assertion failure in https://bugs.llvm.org/show_bug.cgi?id=38427.


Repository:
  rC Clang

https://reviews.llvm.org/D50824

Files:
  lib/Analysis/CFG.cpp
  test/Analysis/cfg-rich-constructors.cpp


Index: test/Analysis/cfg-rich-constructors.cpp
===================================================================
--- test/Analysis/cfg-rich-constructors.cpp
+++ test/Analysis/cfg-rich-constructors.cpp
@@ -1028,3 +1028,18 @@
   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
Index: lib/Analysis/CFG.cpp
===================================================================
--- lib/Analysis/CFG.cpp
+++ lib/Analysis/CFG.cpp
@@ -2421,8 +2421,6 @@
     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 @@
   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>())


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