[analyzer] Suppress warnings coming out of std::basic_string.

The analyzer cannot reason about the internal invariances of the data structure (radar://15194597).

llvm-svn: 194004

clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp

@@ -1549,6 +1549,18 @@ LikelyFalsePositiveSuppressionBRVisitor::getEndPath(BugReporterContext &BRC,
           return 0;
         }
       }
+      // The analyzer issues a false positive on
+      //   std::basic_string<uint8_t> v; v.push_back(1);
+      // because we cannot reason about the internal invariants of the
+      // datastructure.
+      if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) {
+        const CXXRecordDecl *CD = MD->getParent();
+        if (CD->getName() == "basic_string") {
+          BR.markInvalid(getTag(), 0);
+          return 0;
+        }
+      }
+
     }
   }
 

clang/test/Analysis/Inputs/system-header-simulator-cxx.h

@@ -5,6 +5,8 @@
 // suppressed.
 #pragma clang system_header
 
+typedef unsigned char uint8_t;
+
 namespace std {
   template <class T1, class T2>
   struct pair {
@@ -137,6 +139,20 @@ namespace std {
     bool empty() const;
   };
 
+  // basic_string
+  template<class _CharT>
+  class __attribute__ ((__type_visibility__("default"))) basic_string {
+  public:
+    void push_back(int c);
+  };
+  template <class _CharT>
+  void basic_string<_CharT>::push_back(int __c) {
+        // Fake error trigger.
+        // No warning is expected as we are suppressing warning comming
+        // out of std::basic_string.
+        int z = 0;
+        z = 5/z;
+  }
 }
 
 void* operator new(std::size_t, const std::nothrow_t&) throw();

clang/test/Analysis/diagnostics/explicit-suppression.cpp

@@ -12,6 +12,6 @@ void clang_analyzer_eval(bool);
 void testCopyNull(int *I, int *E) {
   std::copy(I, E, (int *)0);
 #ifndef SUPPRESSED
-  // expected-warning@../Inputs/system-header-simulator-cxx.h:108 {{Dereference of null pointer}}
+  // expected-warning@../Inputs/system-header-simulator-cxx.h:110 {{Dereference of null pointer}}
 #endif
 }

clang/test/Analysis/inlining/stl.cpp

@@ -33,3 +33,8 @@ void testList_pop_front(std::list<int> list) {
     list.pop_front();  // no-warning
 }
 
+void testBasicStringSuppression() {
+  std::basic_string<uint8_t> v;
+  v.push_back(1); // no-warning
+}
+