[clang] [clang-format] Allow breaking before bit-field colons (PR #153529)

[via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/153529

Fixes #153448

>From a2ae89cec74b1151680dfa1270ceca336dc5b8a7 Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Wed, 13 Aug 2025 20:09:36 -0700
Subject: [PATCH] [clang-format] Allow breaking before bit-field colons

Fixes #153448
---
 clang/lib/Format/TokenAnnotator.cpp   | 3 ++-
 clang/unittests/Format/FormatTest.cpp | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 4801d27b1395a..184bd7ff49e93 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -6269,7 +6269,8 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
   }
 
   if (Right.is(tok::colon) &&
-      !Right.isOneOf(TT_CtorInitializerColon, TT_InlineASMColon)) {
+      !Right.isOneOf(TT_CtorInitializerColon, TT_InlineASMColon,
+                     TT_BitFieldColon)) {
     return false;
   }
   if (Left.is(tok::colon) && Left.isOneOf(TT_DictLiteral, TT_ObjCMethodExpr)) {
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 96cc650f52a5d..6fc008f029b48 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -4050,6 +4050,10 @@ TEST_F(FormatTest, FormatsBitfields) {
                "  uchar : 8;\n"
                "  uchar other;\n"
                "};");
+  verifyFormat("struct foo {\n"
+               "  uint8_t i_am_a_bit_field_this_long\n"
+               "      : struct_with_constexpr::i_am_a_constexpr_lengthhhhh;\n"
+               "};");
   FormatStyle Style = getLLVMStyle();
   Style.BitFieldColonSpacing = FormatStyle::BFCS_None;
   verifyFormat("struct Bitfields {\n"