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The linux kernel's checkpatch.pl script does several checks
and fixits on the log functions. This clang-tidy checker repeats
these checks so the fixits can be applied tree wide.
The first fixer looks for unneeded 'h' in format strings.
>From this reproducer
printk("%hx\n", a);
checkpatch.pl produces this warning
WARNING: Integer promotion: Using 'h' in '%hx' is unnecessary
+ printk("%hx\n", a);
and this fix
- printk("%hx\n", a);
+ printk("%x\n", a);
LKML discussion
https://lore.kernel.org/lkml/5e3265c241602bb54286fbaae9222070daa4768e.ca...@perches.com/
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D93182
Files:
clang-tools-extra/clang-tidy/linuxkernel/CMakeLists.txt
clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
clang-tools-extra/clang-tidy/linuxkernel/LogFunctionsCheck.cpp
clang-tools-extra/clang-tidy/linuxkernel/LogFunctionsCheck.h
clang-tools-extra/test/clang-tidy/checkers/linuxkernel-logfunctions-h.c
Index: clang-tools-extra/test/clang-tidy/checkers/linuxkernel-logfunctions-h.c
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/linuxkernel-logfunctions-h.c
@@ -0,0 +1,20 @@
+// RUN: %check_clang_tidy %s linuxkernel-log-functions %t
+
+extern printk(const char *, ...) __attribute__((format(printf, 1, 2)));
+
+// scripts/checkpatch.pl produces
+// WARNING: Integer promotion: Using 'h' in '%hx' is unnecessary
+// ... linuxkernel-logfunctions-h.c:10:
+// + printk("%hx\n", a);
+//
+// with --fix-inplace, the change is
+// void f(unsigned char a)
+// {
+// - printk("%hx\n", a);
+// + printk("%x\n", a);
+// }
+void f(unsigned char a) {
+ printk("%hx\n", a);
+ // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: Integer promotion: Using 'h' in '%hx' is unnecessay
+ // CHECK-FIXES: printk("%x\n", a);{{$}}
+}
Index: clang-tools-extra/clang-tidy/linuxkernel/LogFunctionsCheck.h
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/linuxkernel/LogFunctionsCheck.h
@@ -0,0 +1,39 @@
+//===--- LogFunctionsCheck.h - clang-tidy -----------------------*- C++ -*-===//
+//
+// 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_LINUXKERNEL_LOGFUNCTIONSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LINUXKERNEL_LOGFUNCTIONSCHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "clang/Lex/MacroInfo.h"
+#include <vector>
+
+namespace clang {
+namespace tidy {
+namespace linuxkernel {
+
+class LogFunctionsCheck : public ClangTidyCheck {
+
+ enum LogFunctionsFixerKind { LFFK_None, LFFK_H };
+
+public:
+ LogFunctionsCheck(StringRef Name, ClangTidyContext *Context);
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+ void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+
+private:
+ enum LogFunctionsFixerKind FixerKind;
+ const std::string LogFunctionsFixerKindName;
+};
+
+} // namespace linuxkernel
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LINUXKERNEL_LOGFUNCTIONSCHECK_H
Index: clang-tools-extra/clang-tidy/linuxkernel/LogFunctionsCheck.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/linuxkernel/LogFunctionsCheck.cpp
@@ -0,0 +1,95 @@
+//===--- LogFunctionsCheck.cpp - clang-tidy -------------------------------===//
+//
+// 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 "LogFunctionsCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace linuxkernel {
+
+LogFunctionsCheck::LogFunctionsCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context), FixerKind(LFFK_H) {}
+
+void LogFunctionsCheck::registerMatchers(MatchFinder *Finder) {
+ if (FixerKind == LFFK_H) {
+ // From the reproducer
+ // extern int printk(const char *, ...) __attribute__((format(printf, 1, 2)));
+ // void f(unsigned short a) { printk("%hx\n", a); }
+ //
+ // The AST
+ // |-FunctionDecl printk 'int (const char *, ...)' extern
+ // | |-ParmVarDecl 'const char *'
+ // | `-FormatAttr printf 1 2
+ // ...
+ //
+ // `-CompoundStmt
+ // `-CallExpr
+ // |-ImplicitCastExpr
+ // | `-DeclRefExpr Function 'printk' 'int (const char *, ...)'
+ // |-ImplicitCastExpr
+ // | `-ImplicitCastExpr
+ // | `-StringLiteral
+ Finder->addMatcher(
+ compoundStmt(has(
+ callExpr(has(ignoringParenImpCasts(stringLiteral().bind("lit"))),
+ callee(functionDecl(hasAttr(attr::Format)).bind("func")))
+ .bind("call"))),
+ this);
+ }
+}
+
+void LogFunctionsCheck::check(const MatchFinder::MatchResult &Result) {
+ if (FixerKind == LFFK_H) {
+ const auto *Call = Result.Nodes.getNodeAs<CallExpr>("call");
+ const auto *Function = Result.Nodes.getNodeAs<FunctionDecl>("func");
+ const auto *Literal = Result.Nodes.getNodeAs<StringLiteral>("lit");
+ FormatAttr *Format = Function->getAttr<FormatAttr>();
+ unsigned ArgNum = Format->getFormatIdx() - 1;
+ if (Format->getType()->getName() == "printf" &&
+ ArgNum < Call->getNumArgs() &&
+ Literal == Call->getArg(ArgNum)->IgnoreCasts() && Literal->isAscii() &&
+ Literal->getCharByteWidth() == 1) {
+ StringRef LiteralString = Literal->getString();
+ StringRef LookForH[] = {"%hi", "%hd", "%hu", "%hx",
+ "%hhi", "%hhd", "%hhu", "%hhx"};
+ for (auto FoundH : LookForH) {
+ if (LiteralString.contains(FoundH)) {
+ size_t HBegin = LiteralString.find(FoundH) + 1;
+ size_t HEnd = HBegin + 1;
+ StringRef ErrorString = "h";
+ if (FoundH.contains("hh")) {
+ HEnd++;
+ ErrorString = "hh";
+ }
+ SourceLocation BeginLoc = Literal->getLocationOfByte(
+ HBegin, Result.Context->getSourceManager(),
+ Result.Context->getLangOpts(), Result.Context->getTargetInfo());
+ SourceLocation EndLoc = Literal->getLocationOfByte(
+ HEnd, Result.Context->getSourceManager(),
+ Result.Context->getLangOpts(), Result.Context->getTargetInfo());
+ diag(EndLoc, "Integer promotion: Using '%0' in '%1' is unnecessay")
+ << ErrorString << FoundH
+ << FixItHint::CreateRemoval(
+ CharSourceRange::getCharRange(BeginLoc, EndLoc));
+ }
+ }
+ }
+ }
+}
+
+void LogFunctionsCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, "Fixer", "");
+}
+
+} // namespace linuxkernel
+} // namespace tidy
+} // namespace clang
Index: clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
===================================================================
--- clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
+++ clang-tools-extra/clang-tidy/linuxkernel/LinuxKernelTidyModule.cpp
@@ -10,6 +10,7 @@
#include "../ClangTidyModule.h"
#include "../ClangTidyModuleRegistry.h"
#include "ExtraSemiCheck.h"
+#include "LogFunctionsCheck.h"
#include "MustCheckErrsCheck.h"
namespace clang {
@@ -21,6 +22,8 @@
public:
void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
CheckFactories.registerCheck<ExtraSemiCheck>("linuxkernel-extra-semi");
+ CheckFactories.registerCheck<LogFunctionsCheck>(
+ "linuxkernel-log-functions");
CheckFactories.registerCheck<MustCheckErrsCheck>(
"linuxkernel-must-check-errs");
}
Index: clang-tools-extra/clang-tidy/linuxkernel/CMakeLists.txt
===================================================================
--- clang-tools-extra/clang-tidy/linuxkernel/CMakeLists.txt
+++ clang-tools-extra/clang-tidy/linuxkernel/CMakeLists.txt
@@ -6,6 +6,7 @@
add_clang_library(clangTidyLinuxKernelModule
ExtraSemiCheck.cpp
LinuxKernelTidyModule.cpp
+ LogFunctionsCheck.cpp
MustCheckErrsCheck.cpp
LINK_LIBS
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