| 1 | //===--- MisplacedConstCheck.cpp - clang-tidy------------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "MisplacedConstCheck.h" |
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| 10 | #include "clang/AST/ASTContext.h" |
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| 11 | #include "clang/ASTMatchers/ASTMatchFinder.h" |
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| 12 | |
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| 13 | using namespace clang::ast_matchers; |
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| 14 | |
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| 15 | namespace clang::tidy::misc { |
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| 16 | |
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| 17 | void MisplacedConstCheck::registerMatchers(MatchFinder *Finder) { |
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| 18 | auto NonConstAndNonFunctionPointerType = hasType(InnerMatcher: pointerType(unless( |
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| 19 | pointee(anyOf(isConstQualified(), ignoringParens(InnerMatcher: functionType())))))); |
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| 20 | |
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| 21 | Finder->addMatcher( |
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| 22 | NodeMatch: valueDecl(hasType(InnerMatcher: qualType( |
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| 23 | isConstQualified(), |
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| 24 | elaboratedType(namesType(InnerMatcher: typedefType(hasDeclaration( |
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| 25 | InnerMatcher: anyOf(typedefDecl(NonConstAndNonFunctionPointerType) |
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| 26 | .bind(ID: "typedef" ), |
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| 27 | typeAliasDecl(NonConstAndNonFunctionPointerType) |
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| 28 | .bind(ID: "typeAlias" ))))))))) |
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| 29 | .bind(ID: "decl" ), |
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| 30 | Action: this); |
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| 31 | } |
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| 32 | |
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| 33 | static QualType guessAlternateQualification(ASTContext &Context, QualType QT) { |
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| 34 | // We're given a QualType from a typedef where the qualifiers apply to the |
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| 35 | // pointer instead of the pointee. Strip the const qualifier from the pointer |
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| 36 | // type and add it to the pointee instead. |
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| 37 | if (!QT->isPointerType()) |
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| 38 | return QT; |
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| 39 | |
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| 40 | Qualifiers Quals = QT.getLocalQualifiers(); |
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| 41 | Quals.removeConst(); |
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| 42 | |
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| 43 | QualType NewQT = Context.getPointerType( |
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| 44 | T: QualType(QT->getPointeeType().getTypePtr(), Qualifiers::Const)); |
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| 45 | return NewQT.withCVRQualifiers(CVR: Quals.getCVRQualifiers()); |
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| 46 | } |
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| 47 | |
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| 48 | void MisplacedConstCheck::check(const MatchFinder::MatchResult &Result) { |
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| 49 | const auto *Var = Result.Nodes.getNodeAs<ValueDecl>(ID: "decl" ); |
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| 50 | ASTContext &Ctx = *Result.Context; |
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| 51 | QualType CanQT = Var->getType().getCanonicalType(); |
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| 52 | |
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| 53 | SourceLocation AliasLoc; |
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| 54 | const char *AliasType = nullptr; |
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| 55 | if (const auto *Typedef = Result.Nodes.getNodeAs<TypedefDecl>(ID: "typedef" )) { |
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| 56 | AliasLoc = Typedef->getLocation(); |
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| 57 | AliasType = "typedef" ; |
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| 58 | } else if (const auto *TypeAlias = |
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| 59 | Result.Nodes.getNodeAs<TypeAliasDecl>(ID: "typeAlias" )) { |
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| 60 | AliasLoc = TypeAlias->getLocation(); |
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| 61 | AliasType = "type alias" ; |
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| 62 | } else { |
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| 63 | llvm_unreachable("registerMatchers has registered an unknown matcher," |
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| 64 | " code out of sync" ); |
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| 65 | } |
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| 66 | |
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| 67 | diag(Var->getLocation(), "%0 declared with a const-qualified %1; " |
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| 68 | "results in the type being '%2' instead of '%3'" ) |
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| 69 | << Var << AliasType << CanQT.getAsString(Policy: Ctx.getPrintingPolicy()) |
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| 70 | << guessAlternateQualification(Context&: Ctx, QT: CanQT) |
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| 71 | .getAsString(Policy: Ctx.getPrintingPolicy()); |
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| 72 | diag(Loc: AliasLoc, Description: "%0 declared here" , Level: DiagnosticIDs::Note) << AliasType; |
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| 73 | } |
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| 74 | |
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| 75 | } // namespace clang::tidy::misc |
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| 76 | |
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