[clang-tools-extra] [clang-tidy] fix insertion location for function pointers in cppcoreguidelines-init-variables (PR #112091)

[Julian Schmidt via cfe-commits]

https://github.com/5chmidti created 
https://github.com/llvm/llvm-project/pull/112091

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 #112089


>From 6398453039602d28294cbb46e853576c9988a7d6 Mon Sep 17 00:00:00 2001
From: Julian Schmidt <git.julian.schm...@gmail.com>
Date: Sat, 12 Oct 2024 12:34:13 +0200
Subject: [PATCH] [clang-tidy] fix insertion location for function pointers in
 cppcoreguidelines-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 #112089
---
 .../cppcoreguidelines/InitVariablesCheck.cpp       |  8 +++++---
 clang-tools-extra/docs/ReleaseNotes.rst            | 10 +++++++---
 .../checkers/cppcoreguidelines/init-variables.cpp  | 14 ++++++++++++++
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git 
a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp 
b/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
index bdba2314c7056f..3eef2fd12cc8e5 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp
+++ b/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(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst 
b/clang-tools-extra/docs/ReleaseNotes.rst
index 3f7bcde1eb3014..7836ebb8a9e57d 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/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
diff --git 
a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/init-variables.cpp
 
b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/init-variables.cpp
index e3d50946d1cb8f..824431c1bf52fd 100644
--- 
a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/init-variables.cpp
+++ 
b/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
+

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