Analyzer: Teach analyzer how to handle TypeTraitExpr

Summary:
`TypeTraitExpr`s are not supported by the ExprEngine today. Analyzer
creates a sink, and aborts the block. Therefore, certain bugs that
involve type traits intrinsics cannot be detected (see PR24710).

This patch creates boolean `SVal`s for `TypeTraitExpr`s, which are
evaluated by the compiler.

Test within the patch is a summary of PR24710.

Reviewers: zaks.anna, dcoughlin, krememek

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D12482

llvm-svn: 248314

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
index d853286d7fa..4f8ccd0329d 100644
--- a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
@@ -259,6 +259,11 @@ Optional<SVal> SValBuilder::getConstantVal(const Expr *E) {
   case Stmt::CXXBoolLiteralExprClass:
     return makeBoolVal(cast<CXXBoolLiteralExpr>(E));
 
+  case Stmt::TypeTraitExprClass: {
+    const TypeTraitExpr *TE = cast<TypeTraitExpr>(E);
+    return makeTruthVal(TE->getValue(), TE->getType());
+  }
+
   case Stmt::IntegerLiteralClass:
     return makeIntVal(cast<IntegerLiteral>(E));