[clang-tools-extra] [clangd][refactor] Improve function source code qualification logic in DefineOutline (PR #173606)

[Quan Zhuo via cfe-commits]

https://github.com/quanzhuo created https://github.com/llvm/llvm-project/pull/173606

This PR fix https://github.com/clangd/clangd/issues/2573

>From 25166cf972a244e85ccc0904d36e386814edb67b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=85=A8=E5=8D=93?= <quanzhuo at kylinos.cn>
Date: Fri, 26 Dec 2025 15:35:17 +0800
Subject: [PATCH] [clangd][refactor] Improve function source code qualification
 logic in DefineOutline

---
 .../clangd/refactor/tweaks/DefineOutline.cpp             | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp b/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
index 45e7adeeefcd9..6e00f37ca83de 100644
--- a/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DefineOutline.cpp
@@ -236,8 +236,13 @@ getFunctionSourceCode(const FunctionDecl *FD, const DeclContext *TargetContext,
         if (Ref.Qualifier || Ref.Targets.empty() || Ref.NameLoc.isMacroID())
           return;
         // Only qualify return type and function name.
-        if (Ref.NameLoc != FD->getReturnTypeSourceRange().getBegin() &&
-            Ref.NameLoc != FD->getLocation())
+        auto ReturnTypeRange = FD->getReturnTypeSourceRange();
+        if (Ref.NameLoc != FD->getLocation() &&
+            (ReturnTypeRange.isInvalid() ||
+             SM.isBeforeInTranslationUnit(Ref.NameLoc,
+                                          ReturnTypeRange.getBegin()) ||
+             SM.isBeforeInTranslationUnit(ReturnTypeRange.getEnd(),
+                                          Ref.NameLoc)))
           return;
 
         for (const NamedDecl *ND : Ref.Targets) {