Bug 1201314 - Make most of std:: non-memmovable for static analysis purposes. r=mystor r=ehsan

For simplicity, the exceptions are hard-coded in the plugin: currently
std::pair and std::atomic.

build/clang-plugin/clang-plugin.cpp

@@ -279,6 +279,8 @@ public:
   CustomTypeAnnotation(const char *Spelling, const char *Pretty)
       : Spelling(Spelling), Pretty(Pretty){};
 
+  virtual ~CustomTypeAnnotation() {}
+
   // Checks if this custom annotation "effectively affects" the given type.
   bool hasEffectiveAnnotation(QualType T) {
     return directAnnotationReason(T).valid();
@@ -299,6 +301,10 @@ public:
 private:
   bool hasLiteralAnnotation(QualType T) const;
   AnnotationReason directAnnotationReason(QualType T);
+
+protected:
+  // Allow subclasses to apply annotations to external code:
+  virtual bool hasFakeAnnotation(const TagDecl *D) const { return false; }
 };
 
 static CustomTypeAnnotation StackClass =
@@ -313,8 +319,32 @@ static CustomTypeAnnotation NonTemporaryClass =
     CustomTypeAnnotation("moz_non_temporary_class", "non-temporary");
 static CustomTypeAnnotation MustUse =
     CustomTypeAnnotation("moz_must_use", "must-use");
-static CustomTypeAnnotation NonMemMovable =
-  CustomTypeAnnotation("moz_non_memmovable", "non-memmove()able");
+
+class MemMoveAnnotation final : public CustomTypeAnnotation {
+public:
+  MemMoveAnnotation()
+      : CustomTypeAnnotation("moz_non_memmovable", "non-memmove()able") {}
+
+  virtual ~MemMoveAnnotation() {}
+
+protected:
+  bool hasFakeAnnotation(const TagDecl *D) const override {
+    // Annotate everything in ::std, with a few exceptions; see bug
+    // 1201314 for discussion.
+    if (getDeclarationNamespace(D) == "std") {
+      // This doesn't check that it's really ::std::pair and not
+      // ::std::something_else::pair, but should be good enough.
+      StringRef Name = D->getName();
+      if (Name == "pair" || Name == "atomic" || Name == "__atomic_base") {
+        return false;
+      }
+      return true;
+    }
+    return false;
+  }
+};
+
+static MemMoveAnnotation NonMemMovable = MemMoveAnnotation();
 
 class MozChecker : public ASTConsumer, public RecursiveASTVisitor<MozChecker> {
   DiagnosticsEngine &Diag;
@@ -768,7 +798,7 @@ bool CustomTypeAnnotation::hasLiteralAnnotation(QualType T) const {
 #else
   if (const CXXRecordDecl *D = T->getAsCXXRecordDecl()) {
 #endif
-    return MozChecker::hasCustomAnnotation(D, Spelling);
+    return hasFakeAnnotation(D) || MozChecker::hasCustomAnnotation(D, Spelling);
   }
   return false;
 }

build/clang-plugin/tests/TestNonMemMovableStd.cpp

@@ -0,0 +1,21 @@
+#define MOZ_NEEDS_MEMMOVABLE_TYPE __attribute__((annotate("moz_needs_memmovable_type")))
+
+template<class T>
+class MOZ_NEEDS_MEMMOVABLE_TYPE Mover { T mForceInst; }; // expected-error-re 4 {{Cannot instantiate 'Mover<{{.*}}>' with non-memmovable template argument '{{.*}}'}}
+
+namespace std {
+// In theory defining things in std:: like this invokes undefined
+// behavior, but in practice it's good enough for this test case.
+template<class C> class basic_string { };
+typedef basic_string<char> string;
+template<class T, class U> class pair { T mT; U mU; }; // expected-note {{std::pair<bool, std::basic_string<char> >' is a non-memmove()able type because member 'mU' is a non-memmove()able type 'std::basic_string<char>'}}
+class arbitrary_name { };
+}
+
+class HasString { std::string m; }; // expected-note {{'HasString' is a non-memmove()able type because member 'm' is a non-memmove()able type 'std::string' (aka 'basic_string<char>')}}
+
+static Mover<std::string> bad; // expected-note {{instantiation of 'Mover<std::basic_string<char> >' requested here}}
+static Mover<HasString> bad_mem; // expected-note {{instantiation of 'Mover<HasString>' requested here}}
+static Mover<std::arbitrary_name> assumed_bad; // expected-note {{instantiation of 'Mover<std::arbitrary_name>' requested here}}
+static Mover<std::pair<bool, int>> good;
+static Mover<std::pair<bool, std::string>> not_good; // expected-note {{instantiation of 'Mover<std::pair<bool, std::basic_string<char> > >' requested here}}

build/clang-plugin/tests/moz.build

@@ -24,6 +24,7 @@ SOURCES += [
     'TestNoExplicitMoveConstructor.cpp',
     'TestNonHeapClass.cpp',
     'TestNonMemMovable.cpp',
+    'TestNonMemMovableStd.cpp',
     'TestNonTemporaryClass.cpp',
     'TestNoRefcountedInsideLambdas.cpp',
     'TestRefCountedCopyConstructor.cpp',