[clang-format] Fix a bug in BWACS_MultiLine (#136281)

Fixes #136266

Author: owenca

clang/lib/Format/UnwrappedLineFormatter.cpp

@@ -907,7 +907,8 @@ class LineJoiner {
         // { <-- current Line
         //   baz();
         // }
-        if (Line.First == Line.Last && Line.First->isNot(TT_FunctionLBrace) &&
+        if (Line.First == Line.Last &&
+            Line.First->is(TT_ControlStatementLBrace) &&
             Style.BraceWrapping.AfterControlStatement ==
                 FormatStyle::BWACS_MultiLine) {
           return 0;

clang/unittests/Format/FormatTest.cpp

@@ -2866,27 +2866,29 @@ TEST_F(FormatTest, ShortEnums) {
 }
 
 TEST_F(FormatTest, ShortCompoundRequirement) {
+  constexpr StringRef Code("template <typename T>\n"
+                           "concept c = requires(T x) {\n"
+                           "  { x + 1 } -> std::same_as<int>;\n"
+                           "};");
+
   FormatStyle Style = getLLVMStyle();
   EXPECT_TRUE(Style.AllowShortCompoundRequirementOnASingleLine);
-  verifyFormat("template <typename T>\n"
-               "concept c = requires(T x) {\n"
-               "  { x + 1 } -> std::same_as<int>;\n"
-               "};",
-               Style);
+  verifyFormat(Code, Style);
   verifyFormat("template <typename T>\n"
                "concept c = requires(T x) {\n"
                "  { x + 1 } -> std::same_as<int>;\n"
                "  { x + 2 } -> std::same_as<int>;\n"
                "};",
                Style);
+
   Style.AllowShortCompoundRequirementOnASingleLine = false;
   verifyFormat("template <typename T>\n"
                "concept c = requires(T x) {\n"
                "  {\n"
                "    x + 1\n"
                "  } -> std::same_as<int>;\n"
                "};",
-               Style);
+               Code, Style);
   verifyFormat("template <typename T>\n"
                "concept c = requires(T x) {\n"
                "  {\n"
@@ -2897,6 +2899,11 @@ TEST_F(FormatTest, ShortCompoundRequirement) {
                "  } -> std::same_as<int>;\n"
                "};",
                Style);
+
+  Style.AllowShortCompoundRequirementOnASingleLine = true;
+  Style.BreakBeforeBraces = FormatStyle::BS_Custom;
+  Style.BraceWrapping.AfterControlStatement = FormatStyle::BWACS_MultiLine;
+  verifyFormat(Code, Style);
 }
 
 TEST_F(FormatTest, ShortCaseLabels) {