PR-133598: [clang-format]: Add StaticInlineOnly and StaticInline options to ShortFunctionStyle

* fixed small PR requests such as grammar
+ added additional unit tests to test with attribute in different places

Author: Ivan Rymarchyk

clang/include/clang/Format/Format.h

@@ -870,7 +870,7 @@ struct FormatStyle {
     ///   void f() {}
     /// \endcode
     SFS_Inline,
-    /// Only merge functions defined as static inline. Implies ``empty``.
+    /// Merge functions defined as static inline, also merge empty functions.
     /// \code
     ///   void f5(void) {}
     ///   static inline int f6(int a, int b) { return a + b; }

clang/lib/Format/UnwrappedLineFormatter.cpp

@@ -344,20 +344,21 @@ class LineJoiner {
         const auto *FirstNonCommentToken =
             TheLine ? TheLine->getFirstNonComment() : nullptr;
 
-        // Look for 'static' and 'inline' keywords in any order
+        // Look for 'static' and 'inline' keywords in any order.
         bool HasStatic = false;
         bool HasInline = false;
         const FormatToken *Tok = FirstNonCommentToken;
 
-        while (Tok && !Tok->is(TT_FunctionLBrace)) {
+        while (Tok && !Tok->is(TT_FunctionDeclarationName) &&
+               (!HasStatic || !HasInline)) {
           if (Tok->is(tok::kw_static))
             HasStatic = true;
           if (Tok->is(tok::kw_inline))
             HasInline = true;
           Tok = Tok->Next;
         }
 
-        // If we found both static and inline, allow merging
+        // If we found both static and inline, allow merging.
         if (HasStatic && HasInline)
           return true;
       }

clang/unittests/Format/FormatTest.cpp

@@ -15197,6 +15197,56 @@ TEST_F(FormatTest, PullStaticInlineFunctionDefinitionsIntoSingleLine) {
                "{\n"
                "}",
                MergeStaticInline);
+
+  // additional attribute tests
+  verifyFormat("inline static __attribute__((unused)) int f() { return 42; }",
+               "inline static __attribute__((unused)) int f() \n"
+               "{\n"
+               "  return 42; \n"
+               "}",
+               MergeStaticInline);
+  verifyFormat("__attribute__((unused)) inline static int f() { return 42; }",
+               "__attribute__((unused)) inline static int f() \n"
+               "{\n"
+               "  return 42; \n"
+               "}",
+               MergeStaticInline);
+  verifyFormat("inline static int f() __attribute__((unused)) { return 42; }",
+               "inline static int f() \n"
+               "__attribute__((unused)) \n"
+               "{\n"
+               "  return 42; \n"
+               "}",
+               MergeStaticInline);
+  verifyFormat("__attribute__((unused)) inline static int f() { return 42; }",
+               "__attribute__((unused)) inline static int f() \n"
+               "{\n"
+               "  return 42; \n"
+               "}",
+               MergeStaticInline);
+
+  verifyFormat("inline static const int f() { return 42; }",
+               "inline static const int f() \n"
+               "{\n"
+               "  return 42; \n"
+               "}",
+               MergeStaticInline);
+
+  verifyFormat("_Noreturn static inline auto f() { return 42; }",
+               "_Noreturn static inline auto f() \n"
+               "{\n"
+               "  return 42; \n"
+               "}",
+               MergeStaticInline);
+
+  verifyFormat("constexpr auto f() {\n"
+               "  return 42;\n"
+               "}",
+               "constexpr auto f() \n"
+               "{\n"
+               "  return 42; \n"
+               "}",
+               MergeStaticInline);
 }
 
 TEST_F(FormatTest, PullInlineOnlyFunctionDefinitionsIntoSingleLine) {