[clangd] Highlighting auto variables as the deduced type.

Summary:
Done in VisitDeclaratorDecl as the AutoTypeLoc is not deduced.
Scoped to only work for variables.
auto function return values need to be handled in a special way (separate patch for that).
auto's that are in lambdas ar enot highlighted as we don't highlight their underlying type (it's a RecordDecl, but the name is not an identifier so it returns in addToken).

Reviewers: hokein, ilya-biryukov

Subscribers: MaskRay, jkorous, arphaman, kadircet, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65996

llvm-svn: 368546

clang-tools-extra/clangd/SemanticHighlighting.cpp

@@ -97,8 +97,8 @@ public:
   }
 
   bool VisitTypedefNameDecl(TypedefNameDecl *TD) {
-    if(const auto *TSI = TD->getTypeSourceInfo())
-      addTypeLoc(TD->getLocation(), TSI->getTypeLoc());
+    if (const auto *TSI = TD->getTypeSourceInfo())
+      addType(TD->getLocation(), TSI->getTypeLoc().getTypePtr());
     return true;
   }
 
@@ -120,10 +120,8 @@ public:
     // structs. It also makes us not highlight certain namespace qualifiers
     // twice. For elaborated types the actual type is highlighted as an inner
     // TypeLoc.
-    if (TL.getTypeLocClass() == TypeLoc::TypeLocClass::Elaborated)
-      return true;
-
-    addTypeLoc(TL.getBeginLoc(), TL);
+    if (TL.getTypeLocClass() != TypeLoc::TypeLocClass::Elaborated)
+      addType(TL.getBeginLoc(), TL.getTypePtr());
     return true;
   }
 
@@ -144,15 +142,27 @@ public:
         HighlightingTokenCollector>::TraverseConstructorInitializer(CI);
   }
 
-private:
-  void addTypeLoc(SourceLocation Loc, const TypeLoc &TL) {
-    if (const Type *TP = TL.getTypePtr()) {
-      if (const TagDecl *TD = TP->getAsTagDecl())
-        addToken(Loc, TD);
-      if (TP->isBuiltinType())
-        // Builtins must be special cased as they do not have a TagDecl.
-        addToken(Loc, HighlightingKind::Primitive);
+  bool VisitDeclaratorDecl(DeclaratorDecl *D) {
+    if ((!D->getTypeSourceInfo()))
+      return true;
+
+    if (auto *AT = D->getType()->getContainedAutoType()) {
+      const auto Deduced = AT->getDeducedType();
+      if (!Deduced.isNull())
+        addType(D->getTypeSpecStartLoc(), Deduced.getTypePtr());
     }
+    return true;
+  }
+
+private:
+  void addType(SourceLocation Loc, const Type *TP) {
+    if (!TP)
+      return;
+    if (TP->isBuiltinType())
+      // Builtins must be special cased as they do not have a TagDecl.
+      addToken(Loc, HighlightingKind::Primitive);
+    if (const TagDecl *TD = TP->getAsTagDecl())
+      addToken(Loc, TD);
   }
 
   void addToken(SourceLocation Loc, const NamedDecl *D) {

clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp

@@ -99,9 +99,9 @@ TEST(SemanticHighlighting, GetsCorrectTokens) {
       struct {
       } $Variable[[S]];
       $Primitive[[void]] $Function[[foo]]($Primitive[[int]] $Variable[[A]], $Class[[AS]] $Variable[[As]]) {
-        auto $Variable[[VeryLongVariableName]] = 12312;
+        $Primitive[[auto]] $Variable[[VeryLongVariableName]] = 12312;
         $Class[[AS]]     $Variable[[AA]];
-        auto $Variable[[L]] = $Variable[[AA]].$Field[[SomeMember]] + $Variable[[A]];
+        $Primitive[[auto]] $Variable[[L]] = $Variable[[AA]].$Field[[SomeMember]] + $Variable[[A]];
         auto $Variable[[FN]] = [ $Variable[[AA]]]($Primitive[[int]] $Variable[[A]]) -> $Primitive[[void]] {};
         $Variable[[FN]](12312);
       }
@@ -303,6 +303,20 @@ TEST(SemanticHighlighting, GetsCorrectTokens) {
       class $Class[[Bar2]] : public $Class[[Bar]] {
         $Class[[Bar2]]() : $Class[[Bar]]($Class[[Foo]](), $EnumConstant[[EC]]) {}
       };
+    )cpp",
+    R"cpp(
+      enum $Enum[[E]] {
+        $EnumConstant[[E]],
+      };
+      class $Class[[Foo]] {};
+      $Enum[[auto]] $Variable[[AE]] = $Enum[[E]]::$EnumConstant[[E]];
+      $Class[[auto]] $Variable[[AF]] = $Class[[Foo]]();
+      $Class[[decltype]](auto) $Variable[[AF2]] = $Class[[Foo]]();
+      $Class[[auto]] *$Variable[[AFP]] = &$Variable[[AF]];
+      $Enum[[auto]] &$Variable[[AER]] = $Variable[[AE]];
+      $Primitive[[auto]] $Variable[[Form]] = 10.2 + 2 * 4;
+      $Primitive[[decltype]]($Variable[[Form]]) $Variable[[F]] = 10;
+      auto $Variable[[Fun]] = []()->$Primitive[[void]]{};
     )cpp"};
   for (const auto &TestCase : TestCases) {
     checkHighlightings(TestCase);