[clangd] Also mark output arguments of array subscript expressions

... with the "usedAsMutableReference" semantic token modifier.
It's quite unusual to declare the index parameter of a subscript
operator as a non-const reference type, but arguably that makes it even
more helpful to be aware of it when working with such code.

Reviewed By: nridge

Differential Revision: https://reviews.llvm.org/D128892

diff --git a/clang-tools-extra/clangd/SemanticHighlighting.cpp b/clang-tools-extra/clangd/SemanticHighlighting.cpp
index aafff0a..5e0e3b2 100644 (file)
--- a/clang-tools-extra/clangd/SemanticHighlighting.cpp
+++ b/clang-tools-extra/clangd/SemanticHighlighting.cpp
@@ -543,9 +543,14 @@ public:
     // operators as well
     llvm::ArrayRef<const Expr *> Args = {E->getArgs(), E->getNumArgs()};
     if (const auto callOp = dyn_cast<CXXOperatorCallExpr>(E)) {
-      if (callOp->getOperator() != OO_Call)
+      switch (callOp->getOperator()) {
+      case OO_Call:
+      case OO_Subscript:
+        Args = Args.drop_front(); // Drop object parameter
+        break;
+      default:
         return true;
-      Args = Args.drop_front(); // Drop object parameter
+      }
     }
 
     highlightMutableReferenceArguments(

diff --git a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
index db183d6..a40a0f9 100644 (file)
--- a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
@@ -742,6 +742,8 @@ sizeof...($TemplateParameter[[Elements]]);
             void operator()(int);
             void operator()(int, int &);
             void operator()(int, int, const int &);
+            int &operator[](int &);
+            int operator[](int) const;
         };
         void $Function_decl[[fun]](int, const int,
                                    int*, const int*,
@@ -768,9 +770,12 @@ sizeof...($TemplateParameter[[Elements]]);
           [](int&){}($LocalVariable_usedAsMutableReference[[val]]);
           [](const int&){}($LocalVariable[[val]]);
           $Class[[ClassWithOp]] $LocalVariable_decl[[c]];
+          const $Class[[ClassWithOp]] $LocalVariable_decl_readonly[[c2]];
           $LocalVariable[[c]]($LocalVariable[[val]]);
           $LocalVariable[[c]](0, $LocalVariable_usedAsMutableReference[[val]]);
           $LocalVariable[[c]](0, 0, $LocalVariable[[val]]);
+          $LocalVariable[[c]][$LocalVariable_usedAsMutableReference[[val]]];
+          $LocalVariable_readonly[[c2]][$LocalVariable[[val]]];
         }
         struct $Class_decl[[S]] {
           $Class_decl[[S]](int&) {