From 064c5d6ce157da4bbe32a83eab1afebf55f93477 Mon Sep 17 00:00:00 2001
From: Eric Li <li.zhe.hua@gmail.com>
Date: Wed, 26 Nov 2025 23:33:24 -0500
Subject: [PATCH] [clang][Tooling] Fix `getFileRange` returning a range
 spanning across macro arguments

When the start and end token are both spelled in macro arguments, we
still want to reject the range if they come from two separate macro
arguments, as the original specified range is not precisely spelled in
a single sequence of characters in source.
---
 clang/lib/Tooling/Transformer/SourceCode.cpp | 30 ++++++++++++++++----
 clang/unittests/Tooling/SourceCodeTest.cpp   |  2 ++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/clang/lib/Tooling/Transformer/SourceCode.cpp b/clang/lib/Tooling/Transformer/SourceCode.cpp
index 922dafeddf416..fa9bf3427b8a0 100644
--- a/clang/lib/Tooling/Transformer/SourceCode.cpp
+++ b/clang/lib/Tooling/Transformer/SourceCode.cpp
@@ -86,8 +86,12 @@ llvm::Error clang::tooling::validateEditRange(const CharSourceRange &Range,
   return validateRange(Range, SM, /*AllowSystemHeaders=*/false);
 }
 
-static bool spelledInMacroDefinition(SourceLocation Loc,
-                                     const SourceManager &SM) {
+// Returns the location of the top-level macro argument that is the spelling for
+// the expansion `Loc` is from. If `Loc` is spelled in the macro definition,
+// returns an invalid `SourceLocation`.
+static SourceLocation getMacroArgumentSpellingLoc(SourceLocation Loc,
+                                                  const SourceManager &SM) {
+  assert(Loc.isMacroID() && "Location must be in a macro");
   while (Loc.isMacroID()) {
     const auto &Expansion = SM.getSLocEntry(SM.getFileID(Loc)).getExpansion();
     if (Expansion.isMacroArgExpansion()) {
@@ -95,9 +99,26 @@ static bool spelledInMacroDefinition(SourceLocation Loc,
       // in a macro expansion.
       Loc = Expansion.getSpellingLoc();
     } else {
-      return true;
+      return {};
     }
   }
+  return Loc;
+}
+
+static bool spelledInMacroDefinition(CharSourceRange Range,
+                                     const SourceManager &SM) {
+  if (Range.getBegin().isMacroID() && Range.getEnd().isMacroID()) {
+    // Check whether the range is entirely within a single macro argument.
+    auto B = getMacroArgumentSpellingLoc(Range.getBegin(), SM);
+    auto E = getMacroArgumentSpellingLoc(Range.getEnd(), SM);
+    return B.isInvalid() || B != E;
+  }
+
+  if (Range.getBegin().isMacroID())
+    return getMacroArgumentSpellingLoc(Range.getBegin(), SM).isInvalid();
+  if (Range.getEnd().isMacroID())
+    return getMacroArgumentSpellingLoc(Range.getEnd(), SM).isInvalid();
+
   return false;
 }
 
@@ -158,8 +179,7 @@ static CharSourceRange getRange(const CharSourceRange &EditRange,
     Range = Lexer::makeFileCharRange(EditRange, SM, LangOpts);
   } else {
     auto AdjustedRange = getRangeForSplitTokens(EditRange, SM, LangOpts);
-    if (spelledInMacroDefinition(AdjustedRange.getBegin(), SM) ||
-        spelledInMacroDefinition(AdjustedRange.getEnd(), SM))
+    if (spelledInMacroDefinition(AdjustedRange, SM))
       return {};
 
     auto B = SM.getSpellingLoc(AdjustedRange.getBegin());
diff --git a/clang/unittests/Tooling/SourceCodeTest.cpp b/clang/unittests/Tooling/SourceCodeTest.cpp
index 549b77752f1c2..2f59ced0ebc83 100644
--- a/clang/unittests/Tooling/SourceCodeTest.cpp
+++ b/clang/unittests/Tooling/SourceCodeTest.cpp
@@ -510,10 +510,12 @@ TEST(SourceCodeTest, EditInvolvingExpansionIgnoringExpansionShouldFail) {
 #define M1(x) x(1)
 #define M2(x, y) x ## y
 #define M3(x) foobar(x)
+#define M4(x, y) x y
 int foobar(int);
 int a = M1(foobar);
 int b = M2(foo, bar(2));
 int c = M3(3);
+int d = M4(foobar, (4));
 )cpp");
 
   CallsVisitor Visitor;