1//===--- AvoidConstParamsInDecls.cpp - clang-tidy--------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "AvoidConstParamsInDecls.h"
10#include "../utils/LexerUtils.h"
11#include "clang/ASTMatchers/ASTMatchFinder.h"
12#include "clang/ASTMatchers/ASTMatchers.h"
13#include "clang/Lex/Lexer.h"
14
15using namespace clang::ast_matchers;
16
17namespace clang::tidy::readability {
18namespace {
19
20SourceRange getTypeRange(const ParmVarDecl &Param) {
21 return {Param.getBeginLoc(), Param.getLocation().getLocWithOffset(-1)};
22}
23
24// Finds the location of the qualifying `const` token in the `ParmValDecl`'s
25// return type. Returns `std::nullopt` when the parm type is not
26// `const`-qualified like when the type is an alias or a macro.
27static std::optional<Token>
28findConstToRemove(const ParmVarDecl &Param,
29 const MatchFinder::MatchResult &Result) {
30
31 CharSourceRange FileRange = Lexer::makeFileCharRange(
32 Range: CharSourceRange::getTokenRange(R: getTypeRange(Param)),
33 SM: *Result.SourceManager, LangOpts: Result.Context->getLangOpts());
34
35 if (FileRange.isInvalid())
36 return std::nullopt;
37
38 return tidy::utils::lexer::getQualifyingToken(
39 TK: tok::kw_const, Range: FileRange, Context: *Result.Context, SM: *Result.SourceManager);
40}
41
42} // namespace
43
44void AvoidConstParamsInDecls::storeOptions(ClangTidyOptions::OptionMap &Opts) {
45 Options.store(Options&: Opts, LocalName: "IgnoreMacros", Value: IgnoreMacros);
46}
47
48void AvoidConstParamsInDecls::registerMatchers(MatchFinder *Finder) {
49 const auto ConstParamDecl =
50 parmVarDecl(hasType(InnerMatcher: qualType(isConstQualified()))).bind(ID: "param");
51 Finder->addMatcher(NodeMatch: functionDecl(unless(isDefinition()),
52 has(typeLoc(forEach(ConstParamDecl))))
53 .bind(ID: "func"),
54 Action: this);
55}
56
57void AvoidConstParamsInDecls::check(const MatchFinder::MatchResult &Result) {
58 const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>(ID: "func");
59 const auto *Param = Result.Nodes.getNodeAs<ParmVarDecl>(ID: "param");
60
61 if (!Param->getType().isLocalConstQualified())
62 return;
63
64 if (IgnoreMacros &&
65 (Param->getBeginLoc().isMacroID() || Param->getEndLoc().isMacroID())) {
66 // Suppress the check if macros are involved.
67 return;
68 }
69
70 const auto Tok = findConstToRemove(Param: *Param, Result);
71 const auto ConstLocation = Tok ? Tok->getLocation() : Param->getBeginLoc();
72
73 auto Diag = diag(ConstLocation,
74 "parameter %0 is const-qualified in the function "
75 "declaration; const-qualification of parameters only has an "
76 "effect in function definitions");
77 if (Param->getName().empty()) {
78 for (unsigned int I = 0; I < Func->getNumParams(); ++I) {
79 if (Param == Func->getParamDecl(i: I)) {
80 Diag << (I + 1);
81 break;
82 }
83 }
84 } else {
85 Diag << Param;
86 }
87
88 if (Param->getBeginLoc().isMacroID() != Param->getEndLoc().isMacroID()) {
89 // Do not offer a suggestion if the part of the variable declaration comes
90 // from a macro.
91 return;
92 }
93 if (!Tok)
94 return;
95
96 Diag << FixItHint::CreateRemoval(
97 RemoveRange: CharSourceRange::getTokenRange(B: Tok->getLocation(), E: Tok->getLocation()));
98}
99
100} // namespace clang::tidy::readability
101

source code of clang-tools-extra/clang-tidy/readability/AvoidConstParamsInDecls.cpp