[clang-tools-extra] [clang-tidy] Add deprecated-posix-functions check (PR #195641)
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Mon May 4 05:29:34 PDT 2026
llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-tidy
Author: Zeyi Xu (zeyi2)
<details>
<summary>Changes</summary>
In the discussion of #<!-- -->187830, we decided to split the original option in `bugprone-unsafe-functions` to a separate check. This commit implements it.
Currently these functions are checked:
```
bcmp [deprecated] -> memcmp
bcopy [deprecated] -> memmove
bzero [deprecated] -> memset
getpw [deprecated, unsafe] -> getpwuid
vfork [deprecated] -> posix_spawn
```
Also, the suggestion of `bcopy` is changed from `memcpy` to `memmove`, as `memcpy` might cause UB.
This is safe given the manpage:
> Marked as LEGACY in POSIX.1-2001: use memcpy(3) or memmove(3) in new programs. Note that the first two arguments are interchanged for memcpy(3) and memmove(3). POSIX.1-2008 removes the specification of bcopy().
As of AI Usage: Test cases helped by Claude.
Part of #<!-- -->187830
---
Full diff: https://github.com/llvm/llvm-project/pull/195641.diff
9 Files Affected:
- (modified) clang-tools-extra/clang-tidy/portability/CMakeLists.txt (+1)
- (added) clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.cpp (+56)
- (added) clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.h (+31)
- (modified) clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp (+3)
- (modified) clang-tools-extra/docs/ReleaseNotes.rst (+6)
- (modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+1)
- (added) clang-tools-extra/docs/clang-tidy/checks/portability/deprecated-posix-functions.rst (+15)
- (added) clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.c (+68)
- (added) clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.cpp (+91)
``````````diff
diff --git a/clang-tools-extra/clang-tidy/portability/CMakeLists.txt b/clang-tools-extra/clang-tidy/portability/CMakeLists.txt
index 170fedf52130e..6723e4a727b21 100644
--- a/clang-tools-extra/clang-tidy/portability/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/portability/CMakeLists.txt
@@ -6,6 +6,7 @@ set(LLVM_LINK_COMPONENTS
add_clang_library(clangTidyPortabilityModule STATIC
AvoidPragmaOnceCheck.cpp
+ DeprecatedPosixFunctionsCheck.cpp
NoAssemblerCheck.cpp
PortabilityTidyModule.cpp
RestrictSystemIncludesCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.cpp b/clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.cpp
new file mode 100644
index 0000000000000..74a8cfe94d813
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.cpp
@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "DeprecatedPosixFunctionsCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "llvm/ADT/StringSwitch.h"
+
+using namespace clang::ast_matchers;
+using namespace llvm;
+
+namespace clang::tidy::portability {
+
+static constexpr StringRef DeprecatedFunctionId = "DeprecatedFunctions";
+static constexpr StringRef DeclRefId = "DRE";
+
+static StringRef getReplacementFor(StringRef FunctionName) {
+ // TODO: Suggest Annex K replacements when available.
+ return StringSwitch<StringRef>(FunctionName)
+ .Case("bcmp", "memcmp")
+ .Case("bcopy", "memmove")
+ .Case("bzero", "memset")
+ .Case("getpw", "getpwuid")
+ .Case("vfork", "posix_spawn")
+ .Default({});
+}
+
+void DeprecatedPosixFunctionsCheck::registerMatchers(MatchFinder *Finder) {
+ const auto FunctionNamesMatcher =
+ hasAnyName("::bcmp", "::bcopy", "::bzero", "::getpw", "::vfork");
+ Finder->addMatcher(
+ declRefExpr(
+ to(functionDecl(FunctionNamesMatcher).bind(DeprecatedFunctionId)))
+ .bind(DeclRefId),
+ this);
+}
+
+void DeprecatedPosixFunctionsCheck::check(
+ const MatchFinder::MatchResult &Result) {
+ const auto *SourceExpr = Result.Nodes.getNodeAs<DeclRefExpr>(DeclRefId);
+ const auto *FuncDecl =
+ Result.Nodes.getNodeAs<FunctionDecl>(DeprecatedFunctionId);
+ if (!SourceExpr || !FuncDecl)
+ return;
+
+ const StringRef FunctionName = FuncDecl->getName();
+ diag(SourceExpr->getBeginLoc(),
+ "function '%0' is deprecated; '%1' should be used instead")
+ << FunctionName << getReplacementFor(FunctionName);
+}
+
+} // namespace clang::tidy::portability
diff --git a/clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.h b/clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.h
new file mode 100644
index 0000000000000..af1d97e07dc3c
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/portability/DeprecatedPosixFunctionsCheck.h
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_DEPRECATEDPOSIXFUNCTIONSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_DEPRECATEDPOSIXFUNCTIONSCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::portability {
+
+/// Finds uses of deprecated or obsolete POSIX functions and suggests modern
+/// replacements.
+///
+/// For the user-facing documentation see:
+/// https://clang.llvm.org/extra/clang-tidy/checks/portability/deprecated-posix-functions.html
+class DeprecatedPosixFunctionsCheck : public ClangTidyCheck {
+public:
+ DeprecatedPosixFunctionsCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace clang::tidy::portability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_DEPRECATEDPOSIXFUNCTIONSCHECK_H
diff --git a/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
index 1f2340502f685..962a5337c5c35 100644
--- a/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
@@ -9,6 +9,7 @@
#include "../ClangTidy.h"
#include "../ClangTidyModule.h"
#include "AvoidPragmaOnceCheck.h"
+#include "DeprecatedPosixFunctionsCheck.h"
#include "NoAssemblerCheck.h"
#include "RestrictSystemIncludesCheck.h"
#include "SIMDIntrinsicsCheck.h"
@@ -24,6 +25,8 @@ class PortabilityModule : public ClangTidyModule {
void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
CheckFactories.registerCheck<AvoidPragmaOnceCheck>(
"portability-avoid-pragma-once");
+ CheckFactories.registerCheck<DeprecatedPosixFunctionsCheck>(
+ "portability-deprecated-posix-functions");
CheckFactories.registerCheck<NoAssemblerCheck>("portability-no-assembler");
CheckFactories.registerCheck<RestrictSystemIncludesCheck>(
"portability-restrict-system-includes");
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index c9749df481bcd..cc3ace2c74200 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -175,6 +175,12 @@ New checks
Suggests insertion of ``std::move(...)`` to turn copy assignment operator
calls into move assignment ones, when deemed valid and profitable.
+- New :doc:`portability-deprecated-posix-functions
+ <clang-tidy/checks/portability/deprecated-posix-functions>` check.
+
+ Finds uses of deprecated or obsolete POSIX functions and suggests modern
+ replacements.
+
- New :doc:`readability-redundant-lambda-parameter-list
<clang-tidy/checks/readability/redundant-lambda-parameter-list>` check.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 053ce6f0779d9..d19cbfff4598a 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -371,6 +371,7 @@ Clang-Tidy Checks
:doc:`performance-unnecessary-value-param <performance/unnecessary-value-param>`, "Yes"
:doc:`performance-use-std-move <performance/use-std-move>`, "Yes"
:doc:`portability-avoid-pragma-once <portability/avoid-pragma-once>`,
+ :doc:`portability-deprecated-posix-functions <portability/deprecated-posix-functions>`,
:doc:`portability-no-assembler <portability/no-assembler>`,
:doc:`portability-restrict-system-includes <portability/restrict-system-includes>`, "Yes"
:doc:`portability-simd-intrinsics <portability/simd-intrinsics>`,
diff --git a/clang-tools-extra/docs/clang-tidy/checks/portability/deprecated-posix-functions.rst b/clang-tools-extra/docs/clang-tidy/checks/portability/deprecated-posix-functions.rst
new file mode 100644
index 0000000000000..c02dac67c8fd8
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/portability/deprecated-posix-functions.rst
@@ -0,0 +1,15 @@
+.. title:: clang-tidy - portability-deprecated-posix-functions
+
+portability-deprecated-posix-functions
+======================================
+
+Finds uses of deprecated or obsolete POSIX functions and suggests modern
+replacements.
+
+The following functions are checked:
+
+- ``bcmp``, suggested replacement: ``memcmp``
+- ``bcopy``, suggested replacement: ``memmove``
+- ``bzero``, suggested replacement: ``memset``
+- ``getpw``, suggested replacement: ``getpwuid``
+- ``vfork``, suggested replacement: ``posix_spawn``
diff --git a/clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.c b/clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.c
new file mode 100644
index 0000000000000..a286db0559753
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.c
@@ -0,0 +1,68 @@
+// RUN: %check_clang_tidy %s portability-deprecated-posix-functions %t
+
+typedef __SIZE_TYPE__ size_t;
+typedef int pid_t;
+typedef int uid_t;
+
+int bcmp(const void *S1, const void *S2, size_t N);
+void bcopy(const void *Src, void *Dest, size_t N);
+void bzero(void *S, size_t N);
+int getpw(uid_t UId, char *Buf);
+pid_t vfork(void);
+
+#define CALL_BZERO(Buffer, Size) bzero(Buffer, Size)
+#define DEPRECATED_BCMP bcmp
+
+void deprecated_posix_functions(void) {
+ char Buf1[128] = {0};
+ char Buf2[128] = {0};
+
+ bcmp(Buf1, Buf2, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+
+ bcopy(Buf1, Buf2, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bcopy' is deprecated; 'memmove' should be used instead [portability-deprecated-posix-functions]
+
+ bzero(Buf1, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ getpw(0, Buf1);
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'getpw' is deprecated; 'getpwuid' should be used instead [portability-deprecated-posix-functions]
+
+ vfork();
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'vfork' is deprecated; 'posix_spawn' should be used instead [portability-deprecated-posix-functions]
+
+ int (*BcmpPtr)(const void *, const void *, size_t) = bcmp;
+ // CHECK-MESSAGES: :[[@LINE-1]]:56: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+
+ CALL_BZERO(Buf1, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ DEPRECATED_BCMP(Buf1, Buf2, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+}
+
+void deprecated_posix_functions_in_control_flow(int Flag) {
+ char Buf1[128] = {0};
+ char Buf2[128] = {0};
+
+ if (bcmp(Buf1, Buf2, sizeof(Buf1)) == 0)
+ return;
+ // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+
+ for (int I = 0; I < 2; ++I)
+ bzero(Buf1, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ while (getpw(0, Buf1) == 0)
+ break;
+ // CHECK-MESSAGES: :[[@LINE-2]]:10: warning: function 'getpw' is deprecated; 'getpwuid' should be used instead [portability-deprecated-posix-functions]
+
+ Flag ? bcopy(Buf1, Buf2, sizeof(Buf1)) : bzero(Buf2, sizeof(Buf2));
+ // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: function 'bcopy' is deprecated; 'memmove' should be used instead [portability-deprecated-posix-functions]
+ // CHECK-MESSAGES: :[[@LINE-2]]:44: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ if (Flag && vfork() == 0)
+ return;
+ // CHECK-MESSAGES: :[[@LINE-2]]:15: warning: function 'vfork' is deprecated; 'posix_spawn' should be used instead [portability-deprecated-posix-functions]
+}
diff --git a/clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.cpp b/clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.cpp
new file mode 100644
index 0000000000000..a0f04be5675bf
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/portability/deprecated-posix-functions.cpp
@@ -0,0 +1,91 @@
+// RUN: %check_clang_tidy %s portability-deprecated-posix-functions %t
+
+typedef __SIZE_TYPE__ size_t;
+typedef int pid_t;
+typedef int uid_t;
+
+int bcmp(const void *S1, const void *S2, size_t N);
+void bcopy(const void *Src, void *Dest, size_t N);
+void bzero(void *S, size_t N);
+int getpw(uid_t UId, char *Buf);
+pid_t vfork(void);
+
+#define CALL_BZERO(Buffer, Size) bzero(Buffer, Size)
+#define DEPRECATED_BCMP bcmp
+
+void deprecated_posix_functions() {
+ char Buf1[128] = {0};
+ char Buf2[128] = {0};
+
+ bcmp(Buf1, Buf2, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+
+ bcopy(Buf1, Buf2, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bcopy' is deprecated; 'memmove' should be used instead [portability-deprecated-posix-functions]
+
+ bzero(Buf1, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ getpw(0, Buf1);
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'getpw' is deprecated; 'getpwuid' should be used instead [portability-deprecated-posix-functions]
+
+ vfork();
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'vfork' is deprecated; 'posix_spawn' should be used instead [portability-deprecated-posix-functions]
+
+ auto BcmpPtr = &bcmp;
+ // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+
+ CALL_BZERO(Buf1, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ DEPRECATED_BCMP(Buf1, Buf2, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+
+ ::bcmp(Buf1, Buf2, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+}
+
+void deprecated_posix_functions_in_control_flow(bool Flag) {
+ char Buf1[128] = {0};
+ char Buf2[128] = {0};
+
+ if (bcmp(Buf1, Buf2, sizeof(Buf1)) == 0)
+ return;
+ // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: function 'bcmp' is deprecated; 'memcmp' should be used instead [portability-deprecated-posix-functions]
+
+ for (int I = 0; I < 2; ++I)
+ bzero(Buf1, sizeof(Buf1));
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ while (getpw(0, Buf1) == 0)
+ break;
+ // CHECK-MESSAGES: :[[@LINE-2]]:10: warning: function 'getpw' is deprecated; 'getpwuid' should be used instead [portability-deprecated-posix-functions]
+
+ Flag ? bcopy(Buf1, Buf2, sizeof(Buf1)) : bzero(Buf2, sizeof(Buf2));
+ // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: function 'bcopy' is deprecated; 'memmove' should be used instead [portability-deprecated-posix-functions]
+ // CHECK-MESSAGES: :[[@LINE-2]]:44: warning: function 'bzero' is deprecated; 'memset' should be used instead [portability-deprecated-posix-functions]
+
+ if (Flag && vfork() == 0)
+ return;
+ // CHECK-MESSAGES: :[[@LINE-2]]:15: warning: function 'vfork' is deprecated; 'posix_spawn' should be used instead [portability-deprecated-posix-functions]
+}
+
+namespace non_posix {
+int bcmp(const void *S1, const void *S2, size_t N);
+void bcopy(const void *Src, void *Dest, size_t N);
+void bzero(void *S, size_t N);
+int getpw(uid_t UId, char *Buf);
+pid_t vfork(void);
+
+void same_unqualified_names() {
+ char Buf1[128] = {0};
+ char Buf2[128] = {0};
+
+ // No warnings for functions with the same unqualified names outside the global namespace.
+ bcmp(Buf1, Buf2, sizeof(Buf1));
+ bcopy(Buf1, Buf2, sizeof(Buf1));
+ bzero(Buf1, sizeof(Buf1));
+ getpw(0, Buf1);
+ vfork();
+}
+} // namespace non_posix
``````````
</details>
https://github.com/llvm/llvm-project/pull/195641
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