[clang] [clang-format] Fix a bug in wrapping { after else (PR #161048)

[via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/161048

Fixes #160775

>From 4f5986bec1d6bd5961407aea2100872bfcfc7f0f Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Fri, 26 Sep 2025 02:45:53 -0700
Subject: [PATCH] [clang-format] Fix a bug in wrapping { after else

Fixes #160775
---
 clang/lib/Format/FormatToken.h        |  2 +-
 clang/lib/Format/TokenAnnotator.cpp   | 44 +++++++++++++++------------
 clang/unittests/Format/FormatTest.cpp | 21 +++++++++++++
 3 files changed, 46 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Format/FormatToken.h b/clang/lib/Format/FormatToken.h
index e04b0e7af10c0..a28446a540633 100644
--- a/clang/lib/Format/FormatToken.h
+++ b/clang/lib/Format/FormatToken.h
@@ -55,7 +55,7 @@ namespace format {
   TYPE(ConflictAlternative)                                                    \
   TYPE(ConflictEnd)                                                            \
   TYPE(ConflictStart)                                                          \
-  /* l_brace of if/for/while */                                                \
+  /* l_brace of if/for/while/switch/catch */                                   \
   TYPE(ControlStatementLBrace)                                                 \
   TYPE(ControlStatementRBrace)                                                 \
   TYPE(CppCastLParen)                                                          \
diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 67066a104d738..0c9c88a426c89 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -4021,29 +4021,28 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedLine &Line) const {
     }
   }
 
-  if (IsCpp &&
-      (LineIsFunctionDeclaration ||
-       (FirstNonComment && FirstNonComment->is(TT_CtorDtorDeclName))) &&
-      Line.endsWith(tok::semi, tok::r_brace)) {
-    auto *Tok = Line.Last->Previous;
-    while (Tok->isNot(tok::r_brace))
-      Tok = Tok->Previous;
-    if (auto *LBrace = Tok->MatchingParen; LBrace && LBrace->is(TT_Unknown)) {
-      assert(LBrace->is(tok::l_brace));
-      Tok->setBlockKind(BK_Block);
-      LBrace->setBlockKind(BK_Block);
-      LBrace->setFinalizedType(TT_FunctionLBrace);
+  if (IsCpp) {
+    if ((LineIsFunctionDeclaration ||
+         (FirstNonComment && FirstNonComment->is(TT_CtorDtorDeclName))) &&
+        Line.endsWith(tok::semi, tok::r_brace)) {
+      auto *Tok = Line.Last->Previous;
+      while (Tok->isNot(tok::r_brace))
+        Tok = Tok->Previous;
+      if (auto *LBrace = Tok->MatchingParen; LBrace && LBrace->is(TT_Unknown)) {
+        assert(LBrace->is(tok::l_brace));
+        Tok->setBlockKind(BK_Block);
+        LBrace->setBlockKind(BK_Block);
+        LBrace->setFinalizedType(TT_FunctionLBrace);
+      }
     }
-  }
 
-  if (IsCpp && SeenName && AfterLastAttribute &&
-      mustBreakAfterAttributes(*AfterLastAttribute, Style)) {
-    AfterLastAttribute->MustBreakBefore = true;
-    if (LineIsFunctionDeclaration)
-      Line.ReturnTypeWrapped = true;
-  }
+    if (SeenName && AfterLastAttribute &&
+        mustBreakAfterAttributes(*AfterLastAttribute, Style)) {
+      AfterLastAttribute->MustBreakBefore = true;
+      if (LineIsFunctionDeclaration)
+        Line.ReturnTypeWrapped = true;
+    }
 
-  if (IsCpp) {
     if (!LineIsFunctionDeclaration) {
       // Annotate */&/&& in `operator` function calls as binary operators.
       for (const auto *Tok = FirstNonComment; Tok; Tok = Tok->Next) {
@@ -4089,6 +4088,11 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedLine &Line) const {
     }
   }
 
+  if (First->is(TT_ElseLBrace)) {
+    First->CanBreakBefore = true;
+    First->MustBreakBefore = true;
+  }
+
   bool InFunctionDecl = Line.MightBeFunctionDecl;
   bool InParameterList = false;
   for (auto *Current = First->Next; Current; Current = Current->Next) {
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 6a3385a56f53e..fef70365b5e18 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -1364,6 +1364,27 @@ TEST_F(FormatTest, FormatIfWithoutCompoundStatementButElseWith) {
                AllowsMergedIf);
 }
 
+TEST_F(FormatTest, WrapMultipleStatementIfAndElseBraces) {
+  auto Style = getLLVMStyle();
+  Style.AllowShortBlocksOnASingleLine = FormatStyle::SBS_Always;
+  Style.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_AllIfsAndElse;
+  Style.BreakBeforeBraces = FormatStyle::BS_Custom;
+  Style.BraceWrapping.AfterControlStatement = FormatStyle::BWACS_Always;
+  Style.BraceWrapping.BeforeElse = true;
+
+  verifyFormat("if (x)\n"
+               "{\n"
+               "  ++x;\n"
+               "  --y;\n"
+               "}\n"
+               "else\n"
+               "{\n"
+               "  --x;\n"
+               "  ++y;\n"
+               "}",
+               Style);
+}
+
 TEST_F(FormatTest, FormatLoopsWithoutCompoundStatement) {
   verifyFormat("while (true)\n"
                "  ;");