From aec2534e9d666cd1e4930eb83e488e9d541aaeee Mon Sep 17 00:00:00 2001
From: Geoff Romer <gromer@google.com>
Date: Tue, 31 Mar 2026 12:41:26 -0700
Subject: [PATCH] Fix formatting of compound-type variable declarations in
 macros (#6997)

By default clang-format interprets function-like macro invocations as
function calls. E.g. the argument of `CARBON_KIND(llvm::ListSeparator*
sep)` is interpreted as an expression, meaning the `*` is an infix
binary operator, so it inserts a space before the `*`. This change
teaches clang-format that `CARBON_KIND(x)` and
`CARBON_ASSIGN_OR_RETURN(x)` rewrite to `x`, which is close enough to
the truth to enable it to format them correctly. See the [clang-format
docs](https://clang.llvm.org/docs/ClangFormatStyleOptions.html#macros)
for details.
---
 .clang-format                  | 5 +++++
 toolchain/lex/lex.cpp          | 4 ++--
 toolchain/sem_ir/stringify.cpp | 2 +-
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/.clang-format b/.clang-format
index 9225257c145c..37633fd7283e 100644
--- a/.clang-format
+++ b/.clang-format
@@ -27,3 +27,8 @@ StatementMacros: ['ABSTRACT']
 QualifierAlignment: Custom
 QualifierOrder:
   [inline, static, friend, constexpr, const, volatile, restrict, type]
+Macros:
+  # These macros can contain variable declarations, so clang-format needs to
+  # "see through" them in order to format them correctly.
+  - CARBON_ASSIGN_OR_RETURN(x)=x
+  - CARBON_KIND(x)=x
diff --git a/toolchain/lex/lex.cpp b/toolchain/lex/lex.cpp
index 4ca61c56b829..e636fe6a65cf 100644
--- a/toolchain/lex/lex.cpp
+++ b/toolchain/lex/lex.cpp
@@ -1111,14 +1111,14 @@ auto Lexer::LexNumericLiteral(llvm::StringRef source_text, ssize_t& position)
   position += token_size;
 
   CARBON_KIND_SWITCH(literal->ComputeValue(emitter_)) {
-    case CARBON_KIND(NumericLiteral::IntValue && value): {
+    case CARBON_KIND(NumericLiteral::IntValue&& value): {
       return LexTokenWithPayload(TokenKind::IntLiteral,
                                  buffer_.value_stores_->ints()
                                      .AddUnsigned(std::move(value.value))
                                      .AsTokenPayload(),
                                  byte_offset);
     }
-    case CARBON_KIND(NumericLiteral::RealValue && value): {
+    case CARBON_KIND(NumericLiteral::RealValue&& value): {
       auto real_id = buffer_.value_stores_->reals().Add(
           Real{.mantissa = value.mantissa,
                .exponent = value.exponent,
diff --git a/toolchain/sem_ir/stringify.cpp b/toolchain/sem_ir/stringify.cpp
index 435b16d686e1..b6df128e7331 100644
--- a/toolchain/sem_ir/stringify.cpp
+++ b/toolchain/sem_ir/stringify.cpp
@@ -176,7 +176,7 @@ class StepStack {
           PushSpecificNamedConstraint(specific_named_constraint);
           break;
         }
-        case CARBON_KIND(llvm::ListSeparator * sep): {
+        case CARBON_KIND(llvm::ListSeparator* sep): {
           PushString(*sep);
           break;
         }