[llvm-branch-commits] [clang] release/20.x: [clang-format] Fix mismatched break in BlockIndent (#124998) (PR #136238)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/136238

Backport b8734797a3f605c4aaa37fcb5007baa273565460

Requested by: @owenca

>From b51a65f8d0ffb7c547fcc514c3ae686adcbf5b6a Mon Sep 17 00:00:00 2001
From: Gedare Bloom <gedare at rtems.org>
Date: Thu, 30 Jan 2025 20:38:43 -0700
Subject: [PATCH] [clang-format] Fix mismatched break in BlockIndent (#124998)

Near the ColumnLimit a break could be inserted before a right parens
with BlockIndent without a break after the matching left parens. Avoid
these hanging right parens by disallowing breaks before right parens
unless there was a break after the left parens.

Fixes #103306

(cherry picked from commit b8734797a3f605c4aaa37fcb5007baa273565460)
---
 clang/lib/Format/ContinuationIndenter.cpp | 7 +++++++
 clang/unittests/Format/FormatTest.cpp     | 4 ++++
 2 files changed, 11 insertions(+)

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index c311deaa17bb0..6f7d213c0b559 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -349,6 +349,13 @@ bool ContinuationIndenter::canBreak(const LineState &State) {
     }
   }
 
+  // Allow breaking before the right parens with block indentation if there was
+  // a break after the left parens, which is tracked by BreakBeforeClosingParen.
+  if (Style.AlignAfterOpenBracket == FormatStyle::BAS_BlockIndent &&
+      Current.is(tok::r_paren)) {
+    return CurrentState.BreakBeforeClosingParen;
+  }
+
   // Don't allow breaking before a closing brace of a block-indented braced list
   // initializer if there isn't already a break.
   if (Current.is(tok::r_brace) && Current.MatchingParen &&
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 44341fbfe895f..bf3eff129efd5 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -9614,6 +9614,10 @@ TEST_F(FormatTest, AlignsAfterOpenBracket) {
                "        auto aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
                "    ) {};",
                Style);
+  verifyFormat("aaaaaaaaaaaaaaaaaaaaaaaa(\n"
+               "    &bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\n"
+               ");",
+               Style);
 }
 
 TEST_F(FormatTest, ParenthesesAndOperandAlignment) {