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//===--- DeclRefExprUtils.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 "DeclRefExprUtils.h"
#include "Matchers.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
namespace clang::tidy::utils::decl_ref_expr {
using namespace ::clang::ast_matchers;
using llvm::SmallPtrSet;
namespace {
template <typename S> bool isSetDifferenceEmpty(const S &S1, const S &S2) {
for (auto E : S1)
if (S2.count(E) == 0)
return false;
return true;
}
// Extracts all Nodes keyed by ID from Matches and inserts them into Nodes.
template <typename Node>
void extractNodesByIdTo(ArrayRef<BoundNodes> Matches, StringRef ID,
SmallPtrSet<const Node *, 16> &Nodes) {
for (const auto &Match : Matches)
Nodes.insert(Match.getNodeAs<Node>(ID));
}
} // namespace
// Finds all DeclRefExprs where a const method is called on VarDecl or VarDecl
// is the a const reference or value argument to a CallExpr or CXXConstructExpr.
SmallPtrSet<const DeclRefExpr *, 16>
constReferenceDeclRefExprs(const VarDecl &VarDecl, const Stmt &Stmt,
ASTContext &Context) {
auto DeclRefToVar =
declRefExpr(to(varDecl(equalsNode(&VarDecl)))).bind("declRef");
auto ConstMethodCallee = callee(cxxMethodDecl(isConst()));
// Match method call expressions where the variable is referenced as the this
// implicit object argument and operator call expression for member operators
// where the variable is the 0-th argument.
auto Matches = match(
findAll(expr(anyOf(cxxMemberCallExpr(ConstMethodCallee, on(DeclRefToVar)),
cxxOperatorCallExpr(ConstMethodCallee,
hasArgument(0, DeclRefToVar))))),
Stmt, Context);
SmallPtrSet<const DeclRefExpr *, 16> DeclRefs;
extractNodesByIdTo(Matches, "declRef", DeclRefs);
auto ConstReferenceOrValue =
qualType(anyOf(matchers::isReferenceToConst(),
unless(anyOf(referenceType(), pointerType(),
substTemplateTypeParmType()))));
auto ConstReferenceOrValueOrReplaced = qualType(anyOf(
ConstReferenceOrValue,
substTemplateTypeParmType(hasReplacementType(ConstReferenceOrValue))));
auto UsedAsConstRefOrValueArg = forEachArgumentWithParam(
DeclRefToVar, parmVarDecl(hasType(ConstReferenceOrValueOrReplaced)));
Matches = match(findAll(invocation(UsedAsConstRefOrValueArg)), Stmt, Context);
extractNodesByIdTo(Matches, "declRef", DeclRefs);
// References and pointers to const assignments.
Matches =
match(findAll(declStmt(
has(varDecl(hasType(qualType(matchers::isReferenceToConst())),
hasInitializer(ignoringImpCasts(DeclRefToVar)))))),
Stmt, Context);
extractNodesByIdTo(Matches, "declRef", DeclRefs);
Matches =
match(findAll(declStmt(has(varDecl(
hasType(qualType(matchers::isPointerToConst())),
hasInitializer(ignoringImpCasts(unaryOperator(
hasOperatorName("&"), hasUnaryOperand(DeclRefToVar)))))))),
Stmt, Context);
extractNodesByIdTo(Matches, "declRef", DeclRefs);
return DeclRefs;
}
bool isOnlyUsedAsConst(const VarDecl &Var, const Stmt &Stmt,
ASTContext &Context) {
// Collect all DeclRefExprs to the loop variable and all CallExprs and
// CXXConstructExprs where the loop variable is used as argument to a const
// reference parameter.
// If the difference is empty it is safe for the loop variable to be a const
// reference.
auto AllDeclRefs = allDeclRefExprs(Var, Stmt, Context);
auto ConstReferenceDeclRefs = constReferenceDeclRefExprs(Var, Stmt, Context);
return isSetDifferenceEmpty(AllDeclRefs, ConstReferenceDeclRefs);
}
SmallPtrSet<const DeclRefExpr *, 16>
allDeclRefExprs(const VarDecl &VarDecl, const Stmt &Stmt, ASTContext &Context) {
auto Matches = match(
findAll(declRefExpr(to(varDecl(equalsNode(&VarDecl)))).bind("declRef")),
Stmt, Context);
SmallPtrSet<const DeclRefExpr *, 16> DeclRefs;
extractNodesByIdTo(Matches, "declRef", DeclRefs);
return DeclRefs;
}
SmallPtrSet<const DeclRefExpr *, 16>
allDeclRefExprs(const VarDecl &VarDecl, const Decl &Decl, ASTContext &Context) {
auto Matches = match(
decl(forEachDescendant(
declRefExpr(to(varDecl(equalsNode(&VarDecl)))).bind("declRef"))),
Decl, Context);
SmallPtrSet<const DeclRefExpr *, 16> DeclRefs;
extractNodesByIdTo(Matches, "declRef", DeclRefs);
return DeclRefs;
}
bool isCopyConstructorArgument(const DeclRefExpr &DeclRef, const Decl &Decl,
ASTContext &Context) {
auto UsedAsConstRefArg = forEachArgumentWithParam(
declRefExpr(equalsNode(&DeclRef)),
parmVarDecl(hasType(matchers::isReferenceToConst())));
auto Matches = match(
decl(hasDescendant(
cxxConstructExpr(UsedAsConstRefArg, hasDeclaration(cxxConstructorDecl(
isCopyConstructor())))
.bind("constructExpr"))),
Decl, Context);
return !Matches.empty();
}
bool isCopyAssignmentArgument(const DeclRefExpr &DeclRef, const Decl &Decl,
ASTContext &Context) {
auto UsedAsConstRefArg = forEachArgumentWithParam(
declRefExpr(equalsNode(&DeclRef)),
parmVarDecl(hasType(matchers::isReferenceToConst())));
auto Matches = match(
decl(hasDescendant(
cxxOperatorCallExpr(UsedAsConstRefArg, hasOverloadedOperatorName("="),
callee(cxxMethodDecl(isCopyAssignmentOperator())))
.bind("operatorCallExpr"))),
Decl, Context);
return !Matches.empty();
}
} // namespace clang::tidy::utils::decl_ref_expr
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