[clang-format] Correctly format goto labels followed by blocks

There doesn't seem to be an issue on GitHub.  But previously, a space
would be inserted before the goto colon in the code below.

    switch (x) {
    case 0:
    goto_0: {
      action();
      break;
    }
    }

Previously, the colon following a goto label would be annotated as
`TT_InheritanceColon`.  A goto label followed by an opening brace
wasn't recognized.  It is easy to add another line to have
`spaceRequiredBefore` function recognize the case, but I believed it
is more proper to avoid doing the same thing in `UnwrappedLineParser`
and `TokenAnnotator`.  So now the label colons would be labeled in
`UnwrappedLineParser`, and `spaceRequiredBefore` would rely on that.

Previously we had the type `TT_GotoLabelColon` intended for both goto
labels and case labels.  But since handling of goto labels and case
labels differ somewhat, I split it into separate types for goto and
case labels.

This patch doesn't change the behavior for case labels.  I added the
lines annotating case labels because they would previously be
mistakenly annotated as `TT_InheritanceColon` just like goto labels.
And since I added the annotations, the checks for the `case` and
`default` keywords in `spaceRequiredBefore` are not necessary anymore.

Reviewed By: MyDeveloperDay

Differential Revision: https://reviews.llvm.org/D148484

2 files changed, 58 insertions, 2 deletions

diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 5db947abff8c..099a5cb91364 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -2998,6 +2998,17 @@ TEST_F(FormatTest, FormatsLabels) {
                "test_label:;\n"
                "  int i = 0;\n"
                "}");
+  verifyFormat("{\n"
+               "  some_code();\n"
+               "test_label: { some_other_code(); }\n"
+               "}");
+  verifyFormat("{\n"
+               "  some_code();\n"
+               "test_label: {\n"
+               "  some_other_code();\n"
+               "  some_other_code();\n"
+               "}\n"
+               "}");
   FormatStyle Style = getLLVMStyle();
   Style.IndentGotoLabels = false;
   verifyFormat("void f() {\n"
@@ -3022,6 +3033,23 @@ TEST_F(FormatTest, FormatsLabels) {
                "test_label:;\n"
                "  int i = 0;\n"
                "}");
+  verifyFormat("{\n"
+               "  some_code();\n"
+               "test_label: { some_other_code(); }\n"
+               "}",
+               Style);
+  // The opening brace may either be on the same unwrapped line as the colon or
+  // on a separate one. The formatter should recognize both.
+  Style = getLLVMStyle();
+  Style.BreakBeforeBraces = FormatStyle::BraceBreakingStyle::BS_Allman;
+  verifyFormat("{\n"
+               "  some_code();\n"
+               "test_label:\n"
+               "{\n"
+               "  some_other_code();\n"
+               "}\n"
+               "}",
+               Style);
 }
 
 TEST_F(FormatTest, MultiLineControlStatements) {
@@ -16962,6 +16990,19 @@ TEST_F(FormatTest, ConfigurableSpaceBeforeColon) {
                "}\n"
                "}",
                CaseStyle);
+  // Goto labels should not be affected.
+  verifyFormat("switch (x) {\n"
+               "goto_label:\n"
+               "default :\n"
+               "}",
+               CaseStyle);
+  verifyFormat("switch (x) {\n"
+               "goto_label: { break; }\n"
+               "default : {\n"
+               "  break;\n"
+               "}\n"
+               "}",
+               CaseStyle);
 
   FormatStyle NoSpaceStyle = getLLVMStyle();
   EXPECT_EQ(NoSpaceStyle.SpaceBeforeCaseColon, false);
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index cd39661f7f8d..62a83596600e 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -1621,7 +1621,7 @@ TEST_F(TokenAnnotatorTest, UnderstandsVerilogOperators) {
                     "    x;\n"
                     "endcase\n");
   ASSERT_EQ(Tokens.size(), 10u) << Tokens;
-  EXPECT_TOKEN(Tokens[5], tok::colon, TT_GotoLabelColon);
+  EXPECT_TOKEN(Tokens[5], tok::colon, TT_CaseLabelColon);
   Tokens = Annotate("case (x)\n"
                     "  x ? x : x:\n"
                     "    x;\n"
@@ -1629,7 +1629,7 @@ TEST_F(TokenAnnotatorTest, UnderstandsVerilogOperators) {
   ASSERT_EQ(Tokens.size(), 14u) << Tokens;
   EXPECT_TOKEN(Tokens[5], tok::question, TT_ConditionalExpr);
   EXPECT_TOKEN(Tokens[7], tok::colon, TT_ConditionalExpr);
-  EXPECT_TOKEN(Tokens[9], tok::colon, TT_GotoLabelColon);
+  EXPECT_TOKEN(Tokens[9], tok::colon, TT_CaseLabelColon);
   // Non-blocking assignments.
   Tokens = Annotate("a <= b;");
   ASSERT_EQ(Tokens.size(), 5u) << Tokens;
@@ -1752,6 +1752,21 @@ TEST_F(TokenAnnotatorTest, CSharpNullableTypes) {
   EXPECT_TOKEN(Tokens[1], tok::question, TT_ConditionalExpr);
 }
 
+TEST_F(TokenAnnotatorTest, UnderstandsLabels) {
+  auto Tokens = annotate("{ x: break; }");
+  ASSERT_EQ(Tokens.size(), 7u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::colon, TT_GotoLabelColon);
+  Tokens = annotate("{ case x: break; }");
+  ASSERT_EQ(Tokens.size(), 8u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::colon, TT_CaseLabelColon);
+  Tokens = annotate("{ x: { break; } }");
+  ASSERT_EQ(Tokens.size(), 9u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::colon, TT_GotoLabelColon);
+  Tokens = annotate("{ case x: { break; } }");
+  ASSERT_EQ(Tokens.size(), 10u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::colon, TT_CaseLabelColon);
+}
+
 } // namespace
 } // namespace format
 } // namespace clang