[analyzer] Add new debug helper clang_analyzer_warnIfReached.

This will emit a warning if a call to clang_analyzer_warnIfReached is
executed, printing REACHABLE. This is a more explicit way to declare
expected reachability than using clang_analyzer_eval or triggering
a bug (divide-by-zero or null dereference), and unlike the former will
work the same in inlined functions and top-level functions. Like the
other debug helpers, it is part of the debug.ExprInspection checker.

Patch by Jared Grubb!

llvm-svn: 191909

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
index 9522d1d6387..3ed2435b92e 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
@@ -22,6 +22,7 @@ class ExprInspectionChecker : public Checker< eval::Call > {
 
   void analyzerEval(const CallExpr *CE, CheckerContext &C) const;
   void analyzerCheckInlined(const CallExpr *CE, CheckerContext &C) const;
+  void analyzerWarnIfReached(const CallExpr *CE, CheckerContext &C) const;
   void analyzerCrash(const CallExpr *CE, CheckerContext &C) const;
 
   typedef void (ExprInspectionChecker::*FnCheck)(const CallExpr *,
@@ -41,6 +42,7 @@ bool ExprInspectionChecker::evalCall(const CallExpr *CE,
     .Case("clang_analyzer_checkInlined",
           &ExprInspectionChecker::analyzerCheckInlined)
     .Case("clang_analyzer_crash", &ExprInspectionChecker::analyzerCrash)
+    .Case("clang_analyzer_warnIfReached", &ExprInspectionChecker::analyzerWarnIfReached)
     .Default(0);
 
   if (!Handler)
@@ -99,6 +101,17 @@ void ExprInspectionChecker::analyzerEval(const CallExpr *CE,
   C.emitReport(R);
 }
 
+void ExprInspectionChecker::analyzerWarnIfReached(const CallExpr *CE,
+                                                  CheckerContext &C) const {
+  ExplodedNode *N = C.getPredecessor();
+
+  if (!BT)
+    BT.reset(new BugType("Checking analyzer assumptions", "debug"));
+
+  BugReport *R = new BugReport(*BT, "REACHABLE", N);
+  C.emitReport(R);
+}
+
 void ExprInspectionChecker::analyzerCheckInlined(const CallExpr *CE,
                                                  CheckerContext &C) const {
   ExplodedNode *N = C.getPredecessor();