[clang] [clang-format] Apply SpaceBeforeInheritanceColon to enum underlying types (PR #189011)

[Tharun V K via cfe-commits]

https://github.com/tharunvk updated https://github.com/llvm/llvm-project/pull/189011

>From 6aefab3858a4d4b6eb2cba5a5c0d9b921d5c7293 Mon Sep 17 00:00:00 2001
From: Tharun V K <Tharun.V.K at ibm.com>
Date: Fri, 27 Mar 2026 19:47:35 +0530
Subject: [PATCH] [clang-format] Apply SpaceBeforeInheritanceColon to enum
 underlying types

---
 clang/docs/ClangFormatStyleOptions.rst |  4 +++-
 clang/include/clang/Format/Format.h    |  4 +++-
 clang/lib/Format/TokenAnnotator.cpp    |  4 ++--
 clang/unittests/Format/FormatTest.cpp  | 18 ++++++++++++++++++
 4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/clang/docs/ClangFormatStyleOptions.rst b/clang/docs/ClangFormatStyleOptions.rst
index f637b81bb75bc..69def14d7e371 100644
--- a/clang/docs/ClangFormatStyleOptions.rst
+++ b/clang/docs/ClangFormatStyleOptions.rst
@@ -6834,12 +6834,14 @@ the configuration (without a prefix: ``Auto``).
 .. _SpaceBeforeInheritanceColon:
 
 **SpaceBeforeInheritanceColon** (``Boolean``) :versionbadge:`clang-format 7` :ref:`¶ <SpaceBeforeInheritanceColon>`
-  If ``false``, spaces will be removed before inheritance colon.
+  If ``false``, spaces will be removed before inheritance colon
+  and enum underlying type colon.
 
   .. code-block:: c++
 
      true:                                  false:
      class Foo : Bar {}             vs.     class Foo: Bar {}
+     enum E : int {}                        enum E: int {}
 
 .. _SpaceBeforeJsonColon:
 
diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
index 8c90cc2e98121..9247814a3edf2 100644
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -5121,10 +5121,12 @@ struct FormatStyle {
   /// \version 7
   bool SpaceBeforeCtorInitializerColon;
 
-  /// If ``false``, spaces will be removed before inheritance colon.
+  /// If ``false``, spaces will be removed before inheritance colon
+  /// and enum underlying type colon.
   /// \code
   ///    true:                                  false:
   ///    class Foo : Bar {}             vs.     class Foo: Bar {}
+  ///    enum E : int {}                        enum E: int {}
   /// \endcode
   /// \version 7
   bool SpaceBeforeInheritanceColon;
diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index d2cdc28a7da7b..50f290817eea2 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -1444,9 +1444,9 @@ class AnnotatingParser {
                   Scopes.back() == ST_Class)) {
         Tok->setType(TT_BitFieldColon);
       } else if (Contexts.size() == 1 &&
-                 Line.getFirstNonComment()->isNoneOf(tok::kw_enum, tok::kw_case,
+                 Line.getFirstNonComment()->isNoneOf(tok::kw_case,
                                                      tok::kw_default) &&
-                 !Line.startsWith(tok::kw_typedef, tok::kw_enum)) {
+                 !Line.startsWith(tok::kw_typedef)) {
         if (Prev->isOneOf(tok::r_paren, tok::kw_noexcept) ||
             Prev->ClosesRequiresClause) {
           Tok->setType(TT_CtorInitializerColon);
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 2701a7fca7346..8f2c8efd012c6 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -18632,6 +18632,24 @@ TEST_F(FormatTest, ConfigurableSpaceBeforeColon) {
                InvertedSpaceStyle);
 }
 
+TEST_F(FormatTest, EnumUnderlyingTypeUsesInheritanceColonSpacing) {
+  FormatStyle Style = getLLVMStyle();
+
+  Style.SpaceBeforeInheritanceColon = true;
+  verifyFormat("enum A : int {};", Style);
+  verifyFormat("enum class B : int {};", Style);
+  verifyFormat("enum : int { E1 };", Style);
+  verifyFormat("typedef enum : int { E2 } E3;", Style);
+  verifyFormat("typedef enum A : int { E4 } B;", Style);
+
+  Style.SpaceBeforeInheritanceColon = false;
+  verifyFormat("enum A: int {};", Style);
+  verifyFormat("enum class B: int {};", Style);
+  verifyFormat("enum: int { E1 };", Style);
+  verifyFormat("typedef enum: int { E2 } E3;", Style);
+  verifyFormat("typedef enum A: int { E4 } B;", Style);
+}
+
 TEST_F(FormatTest, ConfigurableSpaceAroundPointerQualifiers) {
   FormatStyle Style = getLLVMStyle();