[clang] [clang-format] Change LLVM style to BreakAfterAttributes == ABS_Leave (PR #70360)

[Vlad Serebrennikov via cfe-commits]

https://github.com/Endilll created https://github.com/llvm/llvm-project/pull/70360

This patch addresses some example of bad formatting in Clang. The following commit contains only changes suggested by clang-format: https://github.com/llvm/llvm-project/pull/70349/commits/21689b56d1fc1db0b2263e8049ff656d3757ad36. I believe it's a net negative on readability, with a couple of particularly bad cases. Highlights:
```diff
-    [[clang::preferred_type(bool)]]
-    mutable unsigned CachedLocalOrUnnamed : 1;
+    [[clang::preferred_type(bool)]] mutable unsigned CachedLocalOrUnnamed : 1;
```
```diff
-    [[clang::preferred_type(TypeDependence)]]
-    unsigned Dependence : llvm::BitWidth<TypeDependence>;
+    [[clang::preferred_type(TypeDependence)]] unsigned Dependence
+        : llvm::BitWidth<TypeDependence>;
```
```diff
-    [[clang::preferred_type(ExceptionSpecificationType)]]
-    unsigned ExceptionSpecType : 4;
+    [[clang::preferred_type(
+        ExceptionSpecificationType)]] unsigned ExceptionSpecType : 4;
```

>From 3866a77d62a34e612ff869cde7c743e31350eed2 Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Thu, 26 Oct 2023 20:41:25 +0300
Subject: [PATCH] [clang-format] Change LLVM style to BreakAfterAttributes ==
 ABS_Leave

---
 clang/docs/ReleaseNotes.rst           | 1 +
 clang/lib/Format/Format.cpp           | 2 +-
 clang/unittests/Format/FormatTest.cpp | 7 +++----
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7238386231e1a28..6cd5e3e077e6f3c 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -794,6 +794,7 @@ clang-format
 ------------
 - Add ``AllowBreakBeforeNoexceptSpecifier`` option.
 - Add ``AllowShortCompoundRequirementOnASingleLine`` option.
+- Change ``BreakAfterAttributes`` from ``Never`` to ``Leave`` in LLVM style
 
 libclang
 --------
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index edb33f4af4defef..e1abcac5604a410 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -1476,7 +1476,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
                              /*SplitEmptyFunction=*/true,
                              /*SplitEmptyRecord=*/true,
                              /*SplitEmptyNamespace=*/true};
-  LLVMStyle.BreakAfterAttributes = FormatStyle::ABS_Never;
+  LLVMStyle.BreakAfterAttributes = FormatStyle::ABS_Leave;
   LLVMStyle.BreakAfterJavaFieldAnnotations = false;
   LLVMStyle.BreakArrays = true;
   LLVMStyle.BreakBeforeBinaryOperators = FormatStyle::BOS_None;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index b2d84f2ee389551..5cec49a9173e824 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -26179,7 +26179,7 @@ TEST_F(FormatTest, RemoveSemicolon) {
 
 TEST_F(FormatTest, BreakAfterAttributes) {
   FormatStyle Style = getLLVMStyle();
-  EXPECT_EQ(Style.BreakAfterAttributes, FormatStyle::ABS_Never);
+  EXPECT_EQ(Style.BreakAfterAttributes, FormatStyle::ABS_Leave);
 
   constexpr StringRef Code("[[nodiscard]] inline int f(int &i);\n"
                            "[[foo([[]])]] [[nodiscard]]\n"
@@ -26193,7 +26193,9 @@ TEST_F(FormatTest, BreakAfterAttributes) {
                            "  i = 0;\n"
                            "  return 1;\n"
                            "}");
+  verifyNoChange(Code, Style);
 
+  Style.BreakAfterAttributes = FormatStyle::ABS_Never;
   verifyFormat("[[nodiscard]] inline int f(int &i);\n"
                "[[foo([[]])]] [[nodiscard]] int g(int &i);\n"
                "[[nodiscard]] inline int f(int &i) {\n"
@@ -26206,9 +26208,6 @@ TEST_F(FormatTest, BreakAfterAttributes) {
                "}",
                Code, Style);
 
-  Style.BreakAfterAttributes = FormatStyle::ABS_Leave;
-  verifyNoChange(Code, Style);
-
   Style.BreakAfterAttributes = FormatStyle::ABS_Always;
   verifyFormat("[[nodiscard]]\n"
                "inline int f(int &i);\n"