[clangd] Fix SelectionTree to allow selection range expression in foreach loops.

Reviewers: hokein

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

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66869

llvm-svn: 370191

2 files changed, 26 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/Selection.cpp b/clang-tools-extra/clangd/Selection.cpp
index 96b10f5358c..cd1c84b43c7 100644
--- a/clang-tools-extra/clangd/Selection.cpp
+++ b/clang-tools-extra/clangd/Selection.cpp
@@ -228,6 +228,16 @@ public:
   bool TraverseNestedNameSpecifier(NestedNameSpecifier *) { return true; }
   bool TraverseType(QualType) { return true; }
 
+  // The DeclStmt for the loop variable claims to cover the whole range
+  // inside the parens, this causes the range-init expression to not be hit.
+  // Traverse the loop VarDecl instead, which has the right source range.
+  bool TraverseCXXForRangeStmt(CXXForRangeStmt *S) {
+    return traverseNode(S, [&] {
+      return TraverseStmt(S->getInit()) && TraverseDecl(S->getLoopVariable()) &&
+             TraverseStmt(S->getRangeInit()) && TraverseStmt(S->getBody());
+    });
+  }
+
 private:
   using Base = RecursiveASTVisitor<SelectionVisitor>;
 
diff --git a/clang-tools-extra/clangd/unittests/SelectionTests.cpp b/clang-tools-extra/clangd/unittests/SelectionTests.cpp
index a8ca324adb3..e1a103e8a2b 100644
--- a/clang-tools-extra/clangd/unittests/SelectionTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SelectionTests.cpp
@@ -261,6 +261,22 @@ TEST(SelectionTest, CommonAncestor) {
              struct Foo<U<int>*> {};
           )cpp",
           "TemplateTemplateParmDecl"},
+
+      // Foreach has a weird AST, ensure we can select parts of the range init.
+      // This used to fail, because the DeclStmt for C claimed the whole range.
+      {
+          R"cpp(
+            struct Str {
+              const char *begin();
+              const char *end();
+            };
+            Str makeStr(const char*);
+            void loop() {
+              for (const char* C : [[mak^eStr("foo"^)]])
+                ;
+            }
+          )cpp",
+          "CallExpr"},
   };
   for (const Case &C : Cases) {
     Annotations Test(C.Code);