[clang] [clang-tools-extra] [clangd][HLSL] Fix register attribute source range for hover inside arguments (PR #212881)

[Maria Fernanda Guimarães via cfe-commits]

https://github.com/mafeguimaraes updated https://github.com/llvm/llvm-project/pull/212881

>From 5999ce77963716932030fd6a4400673b903c3c04 Mon Sep 17 00:00:00 2001
From: Maria Fernanda Guimaraes <mariafefe201 at gmail.com>
Date: Wed, 29 Jul 2026 21:46:49 +0000
Subject: [PATCH] [clangd][HLSL] Fix register attribute source range for hover
 inside arguments

Hovering on the slot identifier inside register(t1) (e.g. on t1)
previously produced no tooltip; only hovering on the register keyword
itself worked.

HLSLResourceBindingAttr's SourceRange was zero-width: both the start
and end pointed to the start of the register keyword.
ParseHLSLAnnotations called Attrs.addNew with a single SourceLocation
instead of a full SourceRange. Since clangd's SelectionTree only
matches when the cursor falls inside an attribute's range, a
zero-width range never matched positions inside the argument.

Capture the closing ')' location before it's consumed in the
AT_HLSLResourceBinding case, and pass a full SourceRange (from the
attribute start to the closing paren) to addNew.

Fixes #212749
---
 .../clangd/unittests/HoverTests.cpp           | 24 +++++++++++++++++++
 clang/lib/Parse/ParseHLSL.cpp                 |  5 +++-
 .../test/AST/HLSL/resource_binding_attr.hlsl  |  7 ++++++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/clang-tools-extra/clangd/unittests/HoverTests.cpp b/clang-tools-extra/clangd/unittests/HoverTests.cpp
index e0773708df0eb..bd8b7dbc1eb43 100644
--- a/clang-tools-extra/clangd/unittests/HoverTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HoverTests.cpp
@@ -5311,6 +5311,30 @@ TEST(Hover, FunctionParameters) {
   }
 }
 
+TEST(Hover, HLSLRegisterAttributeRange) {
+  Annotations T(R"hlsl(
+    Texture2D tex : [[^register]]([[^t1]]);
+  )hlsl");
+
+  TestTU TU = TestTU::withCode(T.code());
+  TU.Filename = "TestTU.hlsl";
+  TU.ExtraArgs = {
+      "-x",
+      "hlsl",
+      "--target=dxil-pc-shadermodel6.3-library",
+  };
+
+  auto AST = TU.build();
+
+  for (const auto &P : T.points()) {
+    auto H = getHover(AST, P, format::getLLVMStyle(), nullptr);
+
+    ASSERT_TRUE(H);
+    EXPECT_EQ(H->Name, "register");
+    EXPECT_FALSE(H->Documentation.empty());
+  }
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang
diff --git a/clang/lib/Parse/ParseHLSL.cpp b/clang/lib/Parse/ParseHLSL.cpp
index c727ee3a1f1a6..24d0df1144055 100644
--- a/clang/lib/Parse/ParseHLSL.cpp
+++ b/clang/lib/Parse/ParseHLSL.cpp
@@ -185,6 +185,7 @@ void Parser::ParseHLSLAnnotations(ParsedAttributes &Attrs,
   if (EndLoc)
     *EndLoc = Tok.getLocation();
 
+  SourceLocation AttrEndLoc = Loc;
   ArgsVector ArgExprs;
   switch (AttrKind) {
   case ParsedAttr::AT_HLSLResourceBinding: {
@@ -227,6 +228,7 @@ void Parser::ParseHLSLAnnotations(ParsedAttributes &Attrs,
         fixSeparateAttrArgAndNumber(SpaceStr, SpaceLoc, Tok, ArgExprs, *this,
                                     Actions.Context, PP);
     }
+    AttrEndLoc = Tok.getLocation(); // location of the closing ')'
     if (ExpectAndConsume(tok::r_paren, diag::err_expected)) {
       SkipUntil(tok::r_paren, StopAtSemi); // skip through )
       return;
@@ -337,6 +339,7 @@ void Parser::ParseHLSLAnnotations(ParsedAttributes &Attrs,
     break;
   }
 
-  Attrs.addNew(II, Loc, AttributeScopeInfo(), ArgExprs.data(), ArgExprs.size(),
+  Attrs.addNew(II, SourceRange(Loc, AttrEndLoc), AttributeScopeInfo(),
+               ArgExprs.data(), ArgExprs.size(),
                ParsedAttr::Form::HLSLAnnotation());
 }
diff --git a/clang/test/AST/HLSL/resource_binding_attr.hlsl b/clang/test/AST/HLSL/resource_binding_attr.hlsl
index 2cd2b96bc41b5..637691f04b482 100644
--- a/clang/test/AST/HLSL/resource_binding_attr.hlsl
+++ b/clang/test/AST/HLSL/resource_binding_attr.hlsl
@@ -98,6 +98,13 @@ StructuredBuffer<float> SB[10];
 [[vk::binding(2)]]
 StructuredBuffer<float> SB2[10];
 
+// Regression test: the register attribute's SourceRange should span the
+// full `register(...)` construct (not just the `register` keyword), so
+// that clangd hover works when the cursor is inside the argument list.
+// CHECK: VarDecl {{.*}} rangeTest 'RWBuffer<float>':'hlsl::RWBuffer<float>'
+// CHECK: HLSLResourceBindingAttr {{.*}} <col:29, col:41> "u7" "space0"
+RWBuffer<float> rangeTest : register(u7);
+
 // $Globals should have implicit binding attribute added by SemaHLSL
 // CHECK: HLSLBufferDecl {{.*}} implicit cbuffer $Globals
 // CHECK: HLSLResourceBindingAttr {{.*}} Implicit "" "0"