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alexfhalexfh
committedMar 30, 2016
[clang-tidy] readability check for const params in declarations
Summary: Adds a clang-tidy warning for top-level consts in function declarations. Reviewers: hokein, sbenza, alexfh Subscribers: cfe-commits Patch by Matt Kulukundis! Differential Revision: http://reviews.llvm.org/D18408 llvm-svn: 264856
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‎clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp

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//===--- AvoidConstParamsInDecls.cpp - clang-tidy--------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "AvoidConstParamsInDecls.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/ASTMatchers/ASTMatchers.h"
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#include "clang/Lex/Lexer.h"
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using namespace clang::ast_matchers;
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namespace clang {
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namespace tidy {
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namespace readability {
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namespace {
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SourceRange getTypeRange(const ParmVarDecl &Param) {
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if (Param.getIdentifier() != nullptr)
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return SourceRange(Param.getLocStart(),
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Param.getLocEnd().getLocWithOffset(-1));
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return Param.getSourceRange();
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}
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} // namespace
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void AvoidConstParamsInDecls::registerMatchers(MatchFinder *Finder) {
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const auto ConstParamDecl =
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parmVarDecl(hasType(qualType(isConstQualified()))).bind("param");
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Finder->addMatcher(functionDecl(unless(isDefinition()),
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has(typeLoc(forEach(ConstParamDecl))))
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.bind("func"),
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this);
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}
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void AvoidConstParamsInDecls::check(const MatchFinder::MatchResult &Result) {
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const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func");
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const auto *Param = Result.Nodes.getNodeAs<ParmVarDecl>("param");
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QualType Type = Param->getType();
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if (!Type.isLocalConstQualified())
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return;
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Type.removeLocalConst();
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auto Diag = diag(Param->getLocStart(),
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"parameter %0 is const-qualified in the function "
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"declaration; const-qualification of parameters only has an "
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"effect in function definitions");
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if (Param->getName().empty()) {
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for (unsigned int i = 0; i < Func->getNumParams(); ++i) {
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if (Param == Func->getParamDecl(i)) {
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Diag << (i + 1);
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break;
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}
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}
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} else {
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Diag << Param;
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}
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Diag << FixItHint::CreateReplacement(getTypeRange(*Param),
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Type.getAsString());
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}
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} // namespace readability
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} // namespace tidy
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} // namespace clang

‎clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.h

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//===--- AvoidConstParamsInDecls.h - clang-tidy----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_AVOID_CONST_PARAMS_IN_DECLS_H
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#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_AVOID_CONST_PARAMS_IN_DECLS_H
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#include "../ClangTidy.h"
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namespace clang {
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namespace tidy {
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namespace readability {
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// Detect function declarations that have const value parameters and discourage
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// them.
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class AvoidConstParamsInDecls : public ClangTidyCheck {
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public:
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using ClangTidyCheck::ClangTidyCheck;
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void registerMatchers(ast_matchers::MatchFinder *Finder) override;
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void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
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};
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} // namespace readability
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} // namespace tidy
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} // namespace clang
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#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_AVOID_CONST_PARAMS_IN_DECLS_H

‎clang-tools-extra/clang-tidy/readability/CMakeLists.txt

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set(LLVM_LINK_COMPONENTS support)
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add_clang_library(clangTidyReadabilityModule
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AvoidConstParamsInDecls.cpp
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BracesAroundStatementsCheck.cpp
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ContainerSizeEmptyCheck.cpp
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ElseAfterReturnCheck.cpp

‎clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp

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#include "../ClangTidy.h"
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#include "../ClangTidyModule.h"
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#include "../ClangTidyModuleRegistry.h"
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#include "AvoidConstParamsInDecls.h"
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#include "BracesAroundStatementsCheck.h"
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#include "ContainerSizeEmptyCheck.h"
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#include "ElseAfterReturnCheck.h"
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class ReadabilityModule : public ClangTidyModule {
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public:
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void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
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CheckFactories.registerCheck<AvoidConstParamsInDecls>(
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"readability-avoid-const-params-in-decls");
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CheckFactories.registerCheck<BracesAroundStatementsCheck>(
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"readability-braces-around-statements");
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CheckFactories.registerCheck<ContainerSizeEmptyCheck>(

‎clang-tools-extra/docs/clang-tidy/checks/list.rst

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performance-faster-string-find
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performance-for-range-copy
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performance-implicit-cast-in-loop
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performance-unnecessary-value-param
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performance-unnecessary-copy-initialization
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performance-unnecessary-value-param
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readability-avoid-const-params-in-decls
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readability-braces-around-statements
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readability-container-size-empty
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readability-else-after-return

‎clang-tools-extra/docs/clang-tidy/checks/readability-avoid-const-params-in-decls.rst

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.. title:: clang-tidy - readability-avoid-const-params-in-decls
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readability-avoid-const-params-in-decls
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=======================================
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Checks whether a function declaration has parameters that are top level const.
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`const` values in declarations do not affect the signature of a function, so
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they should not be put there. For example:
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Examples:
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.. code:: c++
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void f(const string); // Bad: const is top level.
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void f(const string&); // Good: const is not top level.
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‎clang-tools-extra/test/clang-tidy/readability-avoid-const-params-in-decls.cpp

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// RUN: %check_clang_tidy %s readability-avoid-const-params-in-decls %t
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using alias_type = bool;
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using alias_const_type = const bool;
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void F1(const int i);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 'i' is const-qualified in the function declaration; const-qualification of parameters only has an effect in function definitions [readability-avoid-const-params-in-decls]
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// CHECK-FIXES: void F1(int i);
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void F2(const int *const i);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 'i' is const-qualified
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// CHECK-FIXES: void F2(const int * i);
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void F3(int const i);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 'i' is const-qualified
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// CHECK-FIXES: void F3(int i);
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void F4(alias_type const i);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 'i' is const-qualified
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// CHECK-FIXES: void F4(alias_type i);
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void F5(const int);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 1 is const-qualified
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// CHECK-FIXES: void F5(int);
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void F6(const int *const);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 1 is const-qualified
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// BUG(b/27584482): void F6(const int *); should be produced
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void F7(int, const int);
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// CHECK-MESSAGES: :[[@LINE-1]]:14: warning: parameter 2 is const-qualified
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// CHECK-FIXES: void F7(int, int);
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void F8(const int, const int);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 1 is const-qualified
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// CHECK-MESSAGES: :[[@LINE-2]]:20: warning: parameter 2 is const-qualified
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// CHECK-FIXES: void F8(int, int);
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void F9(const int long_name);
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// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: parameter 'long_name'
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// CHECK-FIXES: void F9(int long_name);
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void F10(const int *const *const long_name);
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// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: parameter 'long_name'
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// CHECK-FIXES: void F10(const int *const * long_name);
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struct Foo {
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Foo(const int i);
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// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: parameter 'i'
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// CHECK-FIXES: Foo(int i);
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void operator()(const int i);
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// CHECK-MESSAGES: :[[@LINE-1]]:19: warning: parameter 'i'
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// CHECK-FIXES: void operator()(int i);
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};
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// Do not match on definitions
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void NF1(const int i) {}
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void NF2(const int *const i) {}
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void NF3(int const i) {}
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void NF4(alias_type const i) {}
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void NF5(const int) {}
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void NF6(const int *const) {}
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void NF7(int, const int) {}
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void NF8(const int, const int) {}
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// Do not match on other stuff
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void NF(const alias_type& i);
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void NF(const int &i);
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void NF(const int *i);
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void NF(alias_const_type i);
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void NF(const alias_type&);
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void NF(const int&);
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void NF(const int*);
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void NF(const int* const*);
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void NF(alias_const_type);

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