Bug 1192130 - Part 1: Add MOZ_NON_AUTOABLE to restrict using auto in place of certain types, r=ehsan

build/clang-plugin/clang-plugin.cpp

@@ -103,6 +103,11 @@ private:
     virtual void run(const MatchFinder::MatchResult &Result);
   };
 
+  class NoAutoTypeChecker : public MatchFinder::MatchCallback {
+  public:
+    virtual void run(const MatchFinder::MatchResult &Result);
+  };
+
   ScopeChecker scopeChecker;
   ArithmeticArgChecker arithmeticArgChecker;
   TrivialCtorDtorChecker trivialCtorDtorChecker;
@@ -114,6 +119,7 @@ private:
   NeedsNoVTableTypeChecker needsNoVTableTypeChecker;
   NonMemMovableChecker nonMemMovableChecker;
   ExplicitImplicitChecker explicitImplicitChecker;
+  NoAutoTypeChecker noAutoTypeChecker;
   MatchFinder astMatcher;
 };
 
@@ -786,6 +792,15 @@ AST_MATCHER(CXXRecordDecl, isConcreteClass) {
   return !Node.isAbstract();
 }
 
+AST_MATCHER(QualType, autoNonAutoableType) {
+  if (const AutoType *T = Node->getContainedAutoType()) {
+    if (const CXXRecordDecl *Rec = T->getAsCXXRecordDecl()) {
+      return MozChecker::hasCustomAnnotation(Rec, "moz_non_autoable");
+    }
+  }
+  return false;
+}
+
 }
 }
 
@@ -1032,6 +1047,9 @@ DiagnosticsMatcher::DiagnosticsMatcher() {
                       ofClass(allOf(isConcreteClass(), decl().bind("class"))),
                       unless(isMarkedImplicit())).bind("ctor"),
       &explicitImplicitChecker);
+
+  astMatcher.addMatcher(varDecl(hasType(autoNonAutoableType())
+                          ).bind("node"), &noAutoTypeChecker);
 }
 
 // These enum variants determine whether an allocation has occured in the code.
@@ -1348,6 +1366,20 @@ void DiagnosticsMatcher::ExplicitImplicitChecker::run(
   Diag.Report(Ctor->getLocation(), NoteID);
 }
 
+void DiagnosticsMatcher::NoAutoTypeChecker::run(
+    const MatchFinder::MatchResult &Result) {
+  DiagnosticsEngine &Diag = Result.Context->getDiagnostics();
+  unsigned ErrorID = Diag.getDiagnosticIDs()->getCustomDiagID(
+      DiagnosticIDs::Error, "Cannot use auto to declare a variable of type %0");
+  unsigned NoteID = Diag.getDiagnosticIDs()->getCustomDiagID(
+      DiagnosticIDs::Note, "Please write out this type explicitly");
+
+  const VarDecl *D = Result.Nodes.getNodeAs<VarDecl>("node");
+
+  Diag.Report(D->getLocation(), ErrorID) << D->getType();
+  Diag.Report(D->getLocation(), NoteID);
+}
+
 class MozCheckAction : public PluginASTAction {
 public:
   ASTConsumerPtr CreateASTConsumer(CompilerInstance &CI, StringRef fileName) override {

build/clang-plugin/tests/TestNoAutoType.cpp

@@ -0,0 +1,41 @@
+#define MOZ_NON_AUTOABLE __attribute__((annotate("moz_non_autoable")))
+
+template<class T>
+struct MOZ_NON_AUTOABLE ExplicitTypeTemplate {};
+struct MOZ_NON_AUTOABLE ExplicitType {};
+struct NonExplicitType {};
+
+void f() {
+  {
+    ExplicitType a;
+    auto b = a; // expected-error {{Cannot use auto to declare a variable of type 'ExplicitType'}} expected-note {{Please write out this type explicitly}}
+    auto &br = a; // expected-error {{Cannot use auto to declare a variable of type 'ExplicitType &'}} expected-note {{Please write out this type explicitly}}
+    const auto &brc = a; // expected-error {{Cannot use auto to declare a variable of type 'const ExplicitType &'}} expected-note {{Please write out this type explicitly}}
+    auto *bp = &a; // expected-error {{Cannot use auto to declare a variable of type 'ExplicitType *'}} expected-note {{Please write out this type explicitly}}
+    const auto *bpc = &a; // expected-error {{Cannot use auto to declare a variable of type 'const ExplicitType *'}} expected-note {{Please write out this type explicitly}}
+  }
+
+  {
+    ExplicitTypeTemplate<int> a;
+    auto b = a; // expected-error {{Cannot use auto to declare a variable of type 'ExplicitTypeTemplate<int>'}} expected-note {{Please write out this type explicitly}}
+    auto &br = a; // expected-error {{Cannot use auto to declare a variable of type 'ExplicitTypeTemplate<int> &'}} expected-note {{Please write out this type explicitly}}
+    const auto &brc = a; // expected-error {{Cannot use auto to declare a variable of type 'const ExplicitTypeTemplate<int> &'}} expected-note {{Please write out this type explicitly}}
+    auto *bp = &a; // expected-error {{Cannot use auto to declare a variable of type 'ExplicitTypeTemplate<int> *'}} expected-note {{Please write out this type explicitly}}
+    const auto *bpc = &a; // expected-error {{Cannot use auto to declare a variable of type 'const ExplicitTypeTemplate<int> *'}} expected-note {{Please write out this type explicitly}}
+  }
+
+  {
+    NonExplicitType c;
+    auto d = c;
+    auto &dr = c;
+    const auto &drc = c;
+    auto *dp = &c;
+    const auto *dpc = &c;
+  }
+}
+
+ExplicitType A;
+auto B = A; // expected-error {{Cannot use auto to declare a variable of type 'ExplicitType'}} expected-note {{Please write out this type explicitly}}
+
+NonExplicitType C;
+auto D = C;

build/clang-plugin/tests/moz.build

@@ -19,6 +19,7 @@ SOURCES += [
     'TestNeedsNoVTableType.cpp',
     'TestNoAddRefReleaseOnReturn.cpp',
     'TestNoArithmeticExprInArgument.cpp',
+    'TestNoAutoType.cpp',
     'TestNoDuplicateRefCntMember.cpp',
     'TestNonHeapClass.cpp',
     'TestNonMemMovable.cpp',