[clang-tools-extra] [clang-tidy] Fix broken fix-its with `bugprone-not-null-terminated-result` on Windows (PR #162874)

[Victor Chernyakin via cfe-commits]

https://github.com/localspook updated https://github.com/llvm/llvm-project/pull/162874

>From c9eb6d8217672b52842060e52a71bccb173fb8cc Mon Sep 17 00:00:00 2001
From: Victor Chernyakin <chernyakin.victor.j at outlook.com>
Date: Fri, 10 Oct 2025 08:45:26 -0700
Subject: [PATCH 1/2] [clang-tidy] Fix broken fix-its with
 `bugprone-not-null-terminated-result` on Windows

---
 .../clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp   | 7 +++----
 clang-tools-extra/docs/ReleaseNotes.rst                    | 4 ++++
 .../checkers/bugprone/not-null-terminated-result-strlen.c  | 5 -----
 .../bugprone/not-null-terminated-result-wcslen.cpp         | 5 -----
 4 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
index d4676842a97ff..39e3a542aaf6b 100644
--- a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -307,10 +307,9 @@ static void lengthExprHandle(const Expr *LengthExpr,
   // Try to obtain an 'IntegerLiteral' and adjust it.
   if (!IsMacroDefinition) {
     if (const auto *LengthIL = dyn_cast<IntegerLiteral>(LengthExpr)) {
-      size_t NewLength = LengthIL->getValue().getZExtValue() +
-                         (LengthHandle == LengthHandleKind::Increase
-                              ? (isInjectUL(Result) ? 1UL : 1)
-                              : -1);
+      uint64_t NewLength =
+          LengthIL->getValue().getZExtValue() +
+          (LengthHandle == LengthHandleKind::Increase ? 1 : -1);
 
       const auto NewLengthFix = FixItHint::CreateReplacement(
           LengthIL->getSourceRange(),
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index d2d79dcc92ec2..f0b21b88dd998 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -274,6 +274,10 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/narrowing-conversions>` check by fixing
   false positive from analysis of a conditional expression in C.
 
+- Improved :doc:`bugprone-not-null-terminated-result
+  <clang-tidy/checks/bugprone/not-null-terminated-result>` check by fixing
+  bogus fix-its for `strncmp` and `wcsncmp` on Windows.
+
 - Improved :doc:`bugprone-reserved-identifier
   <clang-tidy/checks/bugprone/reserved-identifier>` check by ignoring
   declarations and macros in system headers.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-strlen.c b/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-strlen.c
index 366c1698e4f2d..795ab3d652f9f 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-strlen.c
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-strlen.c
@@ -1,11 +1,6 @@
 // RUN: %check_clang_tidy --match-partial-fixes %s bugprone-not-null-terminated-result %t -- \
 // RUN: -- -I %S/Inputs/not-null-terminated-result
 
-// FIXME: Something wrong with the APInt un/signed conversion on Windows:
-// in 'strncmp(str6, "string", 7);' it tries to inject '4294967302' as length.
-
-// UNSUPPORTED: system-windows
-
 #include "not-null-terminated-result-c.h"
 
 #define __STDC_LIB_EXT1__ 1
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-wcslen.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-wcslen.cpp
index 06e2db9d6e0d6..288c5faabb0ec 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-wcslen.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/not-null-terminated-result-wcslen.cpp
@@ -1,11 +1,6 @@
 // RUN: %check_clang_tidy --match-partial-fixes %s bugprone-not-null-terminated-result %t -- \
 // RUN: -- -std=c++11 -I %S/Inputs/not-null-terminated-result
 
-// FIXME: Something wrong with the APInt un/signed conversion on Windows:
-// in 'wcsncmp(wcs6, L"string", 7);' it tries to inject '4294967302' as length.
-
-// UNSUPPORTED: system-windows
-
 #include "not-null-terminated-result-cxx.h"
 
 #define __STDC_LIB_EXT1__ 1

>From ec3700852b6290c5513ed3746cba568cfbd74ca0 Mon Sep 17 00:00:00 2001
From: Victor Chernyakin <chernyakin.victor.j at outlook.com>
Date: Fri, 10 Oct 2025 10:20:07 -0700
Subject: [PATCH 2/2] Double backticks for code snippets

Co-authored-by: EugeneZelenko <eugene.zelenko at gmail.com>
---
 clang-tools-extra/docs/ReleaseNotes.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index f0b21b88dd998..d9a591cc1036f 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -276,7 +276,7 @@ Changes in existing checks
 
 - Improved :doc:`bugprone-not-null-terminated-result
   <clang-tidy/checks/bugprone/not-null-terminated-result>` check by fixing
-  bogus fix-its for `strncmp` and `wcsncmp` on Windows.
+  bogus fix-its for ``strncmp`` and ``wcsncmp`` on Windows.
 
 - Improved :doc:`bugprone-reserved-identifier
   <clang-tidy/checks/bugprone/reserved-identifier>` check by ignoring