[clang] [clang-format] Correctly annotate requires clause in `&& requires(` (PR #132882)

[Owen Pan via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/132882

Fix #132334

>From 07947452a460c7e4ac3715ccc8c703595670c90a Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Mon, 24 Mar 2025 21:51:04 -0700
Subject: [PATCH] [clang-format] Correctly annotate requires clause in `&&
 requires(`

Fix #132334
---
 clang/lib/Format/UnwrappedLineParser.cpp      | 8 +++++---
 clang/lib/Format/UnwrappedLineParser.h        | 2 +-
 clang/unittests/Format/TokenAnnotatorTest.cpp | 9 +++++++++
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index a6e0596add5d2..f7712bea01c2c 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1708,6 +1708,7 @@ void UnwrappedLineParser::parseStructuralElement(
     break;
   }
 
+  bool SeenEqual = false;
   for (const bool InRequiresExpression =
            OpeningBrace && OpeningBrace->isOneOf(TT_RequiresExpressionLBrace,
                                                  TT_CompoundRequirementLBrace);
@@ -1782,7 +1783,7 @@ void UnwrappedLineParser::parseStructuralElement(
       break;
     case tok::kw_requires: {
       if (IsCpp) {
-        bool ParsedClause = parseRequires();
+        bool ParsedClause = parseRequires(SeenEqual);
         if (ParsedClause)
           return;
       } else {
@@ -2062,6 +2063,7 @@ void UnwrappedLineParser::parseStructuralElement(
         break;
       }
 
+      SeenEqual = true;
       nextToken();
       if (FormatTok->is(tok::l_brace)) {
         // Block kind should probably be set to BK_BracedInit for any language.
@@ -3416,7 +3418,7 @@ void UnwrappedLineParser::parseAccessSpecifier() {
 /// \brief Parses a requires, decides if it is a clause or an expression.
 /// \pre The current token has to be the requires keyword.
 /// \returns true if it parsed a clause.
-bool UnwrappedLineParser::parseRequires() {
+bool UnwrappedLineParser::parseRequires(bool SeenEqual) {
   assert(FormatTok->is(tok::kw_requires) && "'requires' expected");
   auto RequiresToken = FormatTok;
 
@@ -3472,7 +3474,7 @@ bool UnwrappedLineParser::parseRequires() {
     // We check the one token before that for a const:
     // void member(...) const && requires (C<T> ...
     auto PrevPrev = PreviousNonComment->getPreviousNonComment();
-    if (PrevPrev && PrevPrev->is(tok::kw_const)) {
+    if ((PrevPrev && PrevPrev->is(tok::kw_const)) || !SeenEqual) {
       parseRequiresClause(RequiresToken);
       return true;
     }
diff --git a/clang/lib/Format/UnwrappedLineParser.h b/clang/lib/Format/UnwrappedLineParser.h
index 87650c2756cd1..3c5d2c3e030e5 100644
--- a/clang/lib/Format/UnwrappedLineParser.h
+++ b/clang/lib/Format/UnwrappedLineParser.h
@@ -167,7 +167,7 @@ class UnwrappedLineParser {
   void parseAccessSpecifier();
   bool parseEnum();
   bool parseStructLike();
-  bool parseRequires();
+  bool parseRequires(bool SeenEqual);
   void parseRequiresClause(FormatToken *RequiresToken);
   void parseRequiresExpression(FormatToken *RequiresToken);
   void parseConstraintExpression();
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 1ff785110fc34..3480b55dcbae8 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -1399,6 +1399,15 @@ TEST_F(TokenAnnotatorTest, UnderstandsRequiresClausesAndConcepts) {
   ASSERT_EQ(Tokens.size(), 19u) << Tokens;
   EXPECT_TOKEN(Tokens[4], tok::amp, TT_PointerOrReference);
   EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
+
+  Tokens = annotate("void foo() &&\n"
+                    "  requires(!bar)\n"
+                    "{\n"
+                    "  baz();\n"
+                    "}");
+  ASSERT_EQ(Tokens.size(), 17u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::ampamp, TT_PointerOrReference);
+  EXPECT_TOKEN(Tokens[5], tok::kw_requires, TT_RequiresClause);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsRequiresExpressions) {