[clang-tidy] fix insertion location for function pointers in cppcoreg…

…uidelines-init-variables

Previously, the insertion location for the `= nullptr` fix would be
after the variable name. However, if the variable is of type function
pointer that is not an alias, then the insertion would happen inside the
type specification: `void (*a1)(void*);` -> `void (*a1 = nullptr)(void*);`.
With this change, the insertion location will be at the next
'terminator'. That is, at the next `,` or `;`, as that will finish the
current declaration: `void (a1)(void*) = nullptr;`.

Fixes llvm#112089

clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp

@@ -8,9 +8,10 @@
 
 #include "InitVariablesCheck.h"
 
+#include "../utils/LexerUtils.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/Type.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
-#include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 #include <optional>
 
@@ -107,8 +108,9 @@ void InitVariablesCheck::check(const MatchFinder::MatchResult &Result) {
  << MatchedDecl;
  if (*InitializationString != nullptr)
  Diagnostic << FixItHint::CreateInsertion(
- MatchedDecl->getLocation().getLocWithOffset(
- MatchedDecl->getName().size()),
+ utils::lexer::findNextTerminator(MatchedDecl->getLocation(),
+ *Result.SourceManager,
+ Result.Context->getLangOpts()),
  *InitializationString);
  if (AddMathInclude) {
  Diagnostic << IncludeInserter.createIncludeInsertion(

clang-tools-extra/docs/ReleaseNotes.rst

@@ -171,6 +171,10 @@ Changes in existing checks
  fix false positive that floating point variable is only used in increment
  expression.
 
+- Improved :doc:`cppcoreguidelines-init-variables
+ <clang-tidy/checks/cppcoreguidelines-init-variables>` check by fixing the
+ insertion location for function pointers.
+
 - Improved :doc:`cppcoreguidelines-prefer-member-initializer
  <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>` check to
  avoid false positive when member initialization depends on a structured
@@ -185,9 +189,9 @@ Changes in existing checks
  false positive for C++23 deducing this.
 
 - Improved :doc:`modernize-avoid-c-arrays
- <clang-tidy/checks/modernize/avoid-c-arrays>` check to suggest using ``std::span``
- as a replacement for parameters of incomplete C array type in C++20 and 
- ``std::array`` or ``std::vector`` before C++20.
+ <clang-tidy/checks/modernize/avoid-c-arrays>` check to suggest using 
+ ``std::span`` as a replacement for parameters of incomplete C array type in
+ C++20 and ``std::array`` or ``std::vector`` before C++20.
 
 - Improved :doc:`modernize-loop-convert
  <clang-tidy/checks/modernize/loop-convert>` check to fix false positive when

clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/init-variables.cpp

@@ -134,3 +134,17 @@ void test_clang_diagnostic_error() {
  // CHECK-MESSAGES: :[[@LINE-1]]:3: error: unknown type name 'UnknownType' [clang-diagnostic-error]
  // CHECK-FIXES-NOT: {{^}} UnknownType b = 0;{{$}}
 }
+
+namespace gh112089 {
+ void foo(void*);
+ using FPtr = void(*)(void*);
+ void test() {
+ void(*a1)(void*);
+ // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: variable 'a1' is not initialized [cppcoreguidelines-init-variables]
+ // CHECK-FIXES: void(*a1)(void*) = nullptr;
+ FPtr a2;
+ // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: variable 'a2' is not initialized [cppcoreguidelines-init-variables]
+ // CHECK-FIXES: FPtr a2 = nullptr;
+ }
+} // namespace gh112089
+