[analyzer] Support C++ default arguments if they are literal values.

A CXXDefaultArgExpr wraps an Expr owned by a ParmVarDecl belonging to the
called function. In general, ExprEngine and Environment ought to treat this
like a ParenExpr or other transparent wrapper expression, with the inside
expression evaluated first.

However, if we call the same function twice, we'd produce a CFG that contains
the same wrapped expression twice, and we're not set up to handle that. I've
added a FIXME to the CFG builder to come back to that, but meanwhile we can
at least handle expressions that don't need to be explicitly evaluated:
literals. This probably handles many common uses of default parameters:
true/false, null, etc.

Part of PR13385 / <rdar://problem/12156507>

llvm-svn: 162453

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/Environment.cpp b/clang/lib/StaticAnalyzer/Core/Environment.cpp
index 52644f7702f..534f37858c7 100644
--- a/clang/lib/StaticAnalyzer/Core/Environment.cpp
+++ b/clang/lib/StaticAnalyzer/Core/Environment.cpp
@@ -99,6 +99,9 @@ SVal Environment::getSVal(const EnvironmentEntry &Entry,
       case Stmt::SubstNonTypeTemplateParmExprClass:
         E = cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement();
         continue;
+      case Stmt::CXXDefaultArgExprClass:
+        E = cast<CXXDefaultArgExpr>(E)->getExpr();
+        continue;
       case Stmt::ObjCStringLiteralClass: {
         MemRegionManager &MRMgr = svalBuilder.getRegionManager();
         const ObjCStringLiteral *SL = cast<ObjCStringLiteral>(E);