[analyzer] Allow checker writes to specify that no region should be accosiated with the report. (Useful when we report an error on endOfPath or deadSymbols, when the range of the last expression might have nothing to do with the error.)

llvm-svn: 138474

clang/include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h

@@ -138,8 +138,12 @@ public:
   ///
   /// Ranges are used to highlight regions of interest in the source code.
   /// They should be at the same source code line as the BugReport location.
+  /// By default, the source range of the statement corresponding to the error
+  /// node will be used; add a single invalid range to specify absence of
+  /// ranges.
   void addRange(SourceRange R) {
-    assert(R.isValid());
+    assert((R.isValid() || Ranges.empty()) && "Invalid range can only be used "
+                           "to specify that the report does not have a range.");
     Ranges.push_back(R);
   }
 

clang/lib/StaticAnalyzer/Core/BugReporter.cpp

@@ -1273,6 +1273,10 @@ BugReport::getRanges() {
         return std::make_pair(ranges_iterator(), ranges_iterator());
     }
 
+    // User-specified absence of range info.
+    if (Ranges.size() == 1 && !Ranges.begin()->isValid())
+      return std::make_pair(ranges_iterator(), ranges_iterator());
+
     return std::make_pair(Ranges.begin(), Ranges.end());
 }