[clang] [clang-format] Don't always break before << between string literals (PR #92214)

[Owen Pan via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/92214

Instead, leave the line wrapping as is.

Fixes #43887.
Fixes #44363.

>From 40eeb958cef55465fdcee66ab385928c1f202e50 Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Tue, 14 May 2024 19:14:15 -0700
Subject: [PATCH] [clang-format] Don't always break before << between string
 literals

Instead, leave the line wrapping as is.

Fixes #43887.
Fixes #44363.
---
 clang/lib/Format/TokenAnnotator.cpp   |  7 +++++--
 clang/unittests/Format/FormatTest.cpp | 11 +++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index d0aa0838423e4..7c4c76a91f2c5 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -5601,10 +5601,13 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
     return true;
   if (Left.IsUnterminatedLiteral)
     return true;
-  if (Right.is(tok::lessless) && AfterRight && Left.is(tok::string_literal) &&
+
+  if (BeforeLeft && BeforeLeft->is(tok::lessless) &&
+      Left.is(tok::string_literal) && Right.is(tok::lessless) && AfterRight &&
       AfterRight->is(tok::string_literal)) {
-    return true;
+    return Right.NewlinesBefore > 0;
   }
+
   if (Right.is(TT_RequiresClause)) {
     switch (Style.RequiresClausePosition) {
     case FormatStyle::RCPS_OwnLine:
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index e6f8e4a06515e..6f57f10e12e88 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -10539,6 +10539,17 @@ TEST_F(FormatTest, KeepStringLabelValuePairsOnALine) {
       "                  bbbbbbbbbbbbbbbbbbbbbbb);");
 }
 
+TEST_F(FormatTest, WrapBeforeInsertionOperatorbetweenStringLiterals) {
+  verifyFormat("QStringList() << \"foo\" << \"bar\";");
+
+  verifyNoChange("QStringList() << \"foo\"\n"
+                 "              << \"bar\";");
+
+  verifyFormat("log_error(log, \"foo\" << \"bar\");",
+               "log_error(log, \"foo\"\n"
+               "                   << \"bar\");");
+}
+
 TEST_F(FormatTest, UnderstandsEquals) {
   verifyFormat(
       "aaaaaaaaaaaaaaaaa =\n"