[PATCH] D116218: [clangd] Fix selection on multi-dimensional array.

[Haojian Wu via Phabricator via cfe-commits]

hokein created this revision.
hokein added a reviewer: sammccall.
Herald added subscribers: usaxena95, kadircet, arphaman.
hokein requested review of this revision.
Herald added subscribers: MaskRay, ilya-biryukov.
Herald added a project: clang-tools-extra.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D116218

Files:
  clang-tools-extra/clangd/Selection.cpp
  clang-tools-extra/clangd/unittests/SelectionTests.cpp


Index: clang-tools-extra/clangd/unittests/SelectionTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/SelectionTests.cpp
+++ clang-tools-extra/clangd/unittests/SelectionTests.cpp
@@ -318,6 +318,13 @@
       {"[[st^ruct {int x;}]] y;", "CXXRecordDecl"},
       {"[[struct {int x;} ^y]];", "VarDecl"},
       {"struct {[[int ^x]];} y;", "FieldDecl"},
+
+      // Tricky case: nested ConstantArrayTypeLocs have the same token range.
+      {"const int x = 1, y = 2; int array[^[[x]]][10][y];", "DeclRefExpr"},
+      {"const int x = 1, y = 2; int array[x][10][^[[y]]];", "DeclRefExpr"},
+      {"const int x = 1, y = 2; int array[x][^[[10]]][y];", "IntegerLiteral"},
+      {"const int x = 1, y = 2; [[i^nt]] array[x][10][y];", "BuiltinTypeLoc"},
+
       // FIXME: the AST has no location info for qualifiers.
       {"const [[a^uto]] x = 42;", "AutoTypeLoc"},
       {"[[co^nst auto x = 42]];", "VarDecl"},
Index: clang-tools-extra/clangd/Selection.cpp
===================================================================
--- clang-tools-extra/clangd/Selection.cpp
+++ clang-tools-extra/clangd/Selection.cpp
@@ -511,6 +511,24 @@
   bool TraverseTypeLoc(TypeLoc X) {
     return traverseNode(&X, [&] { return Base::TraverseTypeLoc(X); });
   }
+
+  // Multi-dimensional arrays are tricky:
+  //
+  // int array[Size][10];
+  // ~~~      ~~~~~~~~~~  ConstantArrayTypeLoc int[Size][10]
+  // ~~~            ~~~~  |-ConstantArrayTypeLoc int[10]
+  //
+  // We have two nested ConstantArrayTypeLocs, both claim the same token range.
+  // We want to the SizeExpr in the first ConstantArrayTypeLoc to own the "Size"
+  // token rather than the second ConstantArrayTypeLoc.
+  // We override the default ConstantArrayTypeLoc traversal behavior by swaping
+  // the traversal order of SizeExpr and ElementTypeLoc, which gives a chance
+  // for the SizeExpr to claim its tokens.
+  bool TraverseConstantArrayTypeLoc(ConstantArrayTypeLoc X) {
+    if (!Base::TraverseStmt(X.getSizeExpr()))
+      return false;
+    return TraverseTypeLoc(X.getElementLoc());
+  }
   bool TraverseTemplateArgumentLoc(const TemplateArgumentLoc &X) {
     return traverseNode(&X,
                         [&] { return Base::TraverseTemplateArgumentLoc(X); });


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