[clang] [clang-format] Add a new style for the clang-format source code (PR #69814)

[Owen Pan via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/69814

None

>From 78a2661ba7a18ecf8b09be71f6959fbc9fcf70fe Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Fri, 20 Oct 2023 23:01:38 -0700
Subject: [PATCH] [clang-format] Add a new style for the clang-format source
 code

---
 clang/include/clang/Format/Format.h        |  2 ++
 clang/lib/Format/Format.cpp                | 18 +++++++++++++++---
 clang/unittests/Format/ConfigParseTest.cpp |  7 +++++++
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
index ed92ef6fc655522..4c344135d25163c 100644
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -4861,6 +4861,8 @@ FormatStyle getGNUStyle();
 /// https://docs.microsoft.com/en-us/visualstudio/ide/editorconfig-code-style-settings-reference?view=vs-2017
 FormatStyle getMicrosoftStyle(FormatStyle::LanguageKind Language);
 
+FormatStyle getClangFormatStyle();
+
 /// Returns style indicating formatting should be not applied at all.
 FormatStyle getNoStyle();
 
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index acbed56a86e141f..2f988c4eaf35a57 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -834,8 +834,8 @@ template <> struct MappingTraits<FormatStyle> {
 
     StringRef BasedOnStyle;
     if (IO.outputting()) {
-      StringRef Styles[] = {"LLVM",   "Google", "Chromium", "Mozilla",
-                            "WebKit", "GNU",    "Microsoft"};
+      StringRef Styles[] = {"LLVM",   "Google", "Chromium",  "Mozilla",
+                            "WebKit", "GNU",    "Microsoft", "clang-format"};
       for (StringRef StyleName : Styles) {
         FormatStyle PredefinedStyle;
         if (getPredefinedStyle(StyleName, Style.Language, &PredefinedStyle) &&
@@ -1915,6 +1915,16 @@ FormatStyle getMicrosoftStyle(FormatStyle::LanguageKind Language) {
   return Style;
 }
 
+FormatStyle getClangFormatStyle() {
+  FormatStyle Style = getLLVMStyle();
+  Style.InsertBraces = true;
+  Style.InsertNewlineAtEOF = true;
+  Style.LineEnding = FormatStyle::LE_LF;
+  Style.RemoveBracesLLVM = true;
+  Style.RemoveParentheses = FormatStyle::RPS_ReturnStatement;
+  return Style;
+}
+
 FormatStyle getNoStyle() {
   FormatStyle NoStyle = getLLVMStyle();
   NoStyle.DisableFormat = true;
@@ -1939,6 +1949,8 @@ bool getPredefinedStyle(StringRef Name, FormatStyle::LanguageKind Language,
     *Style = getGNUStyle();
   else if (Name.equals_insensitive("microsoft"))
     *Style = getMicrosoftStyle(Language);
+  else if (Name.equals_insensitive("clang-format"))
+    *Style = getClangFormatStyle();
   else if (Name.equals_insensitive("none"))
     *Style = getNoStyle();
   else if (Name.equals_insensitive("inheritparentconfig"))
@@ -3841,7 +3853,7 @@ LangOptions getFormattingLangOpts(const FormatStyle &Style) {
 const char *StyleOptionHelpDescription =
     "Set coding style. <string> can be:\n"
     "1. A preset: LLVM, GNU, Google, Chromium, Microsoft,\n"
-    "   Mozilla, WebKit.\n"
+    "   Mozilla, WebKit, clang-format.\n"
     "2. 'file' to load style configuration from a\n"
     "   .clang-format file in one of the parent directories\n"
     "   of the source file (for stdin, see --assume-filename).\n"
diff --git a/clang/unittests/Format/ConfigParseTest.cpp b/clang/unittests/Format/ConfigParseTest.cpp
index c35c82955f6a558..ba79c8d72f09552 100644
--- a/clang/unittests/Format/ConfigParseTest.cpp
+++ b/clang/unittests/Format/ConfigParseTest.cpp
@@ -63,6 +63,13 @@ TEST(ConfigParseTest, GetsPredefinedStyleByName) {
   EXPECT_TRUE(getPredefinedStyle("gnU", FormatStyle::LK_Cpp, &Styles[2]));
   EXPECT_ALL_STYLES_EQUAL(Styles);
 
+  Styles[0] = getClangFormatStyle();
+  EXPECT_TRUE(
+      getPredefinedStyle("clang-format", FormatStyle::LK_Cpp, &Styles[1]));
+  EXPECT_TRUE(
+      getPredefinedStyle("Clang-format", FormatStyle::LK_Cpp, &Styles[2]));
+  EXPECT_ALL_STYLES_EQUAL(Styles);
+
   EXPECT_FALSE(getPredefinedStyle("qwerty", FormatStyle::LK_Cpp, &Styles[0]));
 }