[clang-tidy] Fix readability-use-concise-preprocessor-directives check (llvm#166000)

Closes [llvm#157527](llvm#157527)

Author: zeyi2

clang-tools-extra/clang-tidy/readability/UseConcisePreprocessorDirectivesCheck.cpp

@@ -91,7 +91,10 @@ class IfPreprocessorCallbacks final : public PPCallbacks {
     Check.diag(
         DirectiveLoc,
         "preprocessor condition can be written more concisely using '#%0'")
-        << FixItHint::CreateReplacement(DirectiveLoc, Replacements[Inverted])
+        << FixItHint::CreateReplacement(
+               CharSourceRange::getCharRange(DirectiveLoc,
+                                             ConditionRange.getBegin()),
+               (Replacements[Inverted].str() + " "))
         << FixItHint::CreateReplacement(ConditionRange, Macro)
         << Replacements[Inverted];
   }

clang-tools-extra/docs/ReleaseNotes.rst

@@ -480,6 +480,10 @@ Changes in existing checks
   <clang-tidy/checks/readability/uppercase-literal-suffix>` check to recognize
   literal suffixes added in C++23 and C23.
 
+- Improved :doc:`readability-use-concise-preprocessor-directives
+  <clang-tidy/checks/readability/use-concise-preprocessor-directives>` check to
+  generate correct fix-its for forms without a space after the directive.
+
 Removed checks
 ^^^^^^^^^^^^^^
 

clang-tools-extra/test/clang-tidy/checkers/readability/use-concise-preprocessor-directives.cpp

@@ -28,6 +28,14 @@
 #  elif (defined(BAR))
 #endif
 
+// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifdef' [readability-use-concise-preprocessor-directives]
+// CHECK-FIXES: #ifdef FOO
+#if(defined(FOO))
+// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
+// CHECK-FIXES-23: #elifdef BAR
+#elif(defined(BAR))
+#endif
+
 // CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifdef' [readability-use-concise-preprocessor-directives]
 // CHECK-FIXES: #ifdef FOO
 #if (defined FOO)