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//===--- StringIntegerAssignmentCheck.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 "StringIntegerAssignmentCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace bugprone {
void StringIntegerAssignmentCheck::registerMatchers(MatchFinder *Finder) {
if (!getLangOpts().CPlusPlus)
return;
Finder->addMatcher(
cxxOperatorCallExpr(
anyOf(hasOverloadedOperatorName("="),
hasOverloadedOperatorName("+=")),
callee(cxxMethodDecl(ofClass(classTemplateSpecializationDecl(
hasName("::std::basic_string"),
hasTemplateArgument(0, refersToType(hasCanonicalType(
qualType().bind("type")))))))),
hasArgument(
1,
ignoringImpCasts(
expr(hasType(isInteger()), unless(hasType(isAnyCharacter())),
// Ignore calls to tolower/toupper (see PR27723).
unless(callExpr(callee(functionDecl(
hasAnyName("tolower", "std::tolower", "toupper",
"std::toupper"))))),
// Do not warn if assigning e.g. `CodePoint` to
// `basic_string<CodePoint>`
unless(hasType(qualType(
hasCanonicalType(equalsBoundNode("type"))))))
.bind("expr"))),
unless(isInTemplateInstantiation())),
this);
}
static bool isLikelyCharExpression(const Expr *Argument,
const ASTContext &Ctx) {
const auto *BinOp = dyn_cast<BinaryOperator>(Argument);
if (!BinOp)
return false;
const auto *LHS = BinOp->getLHS()->IgnoreParenImpCasts();
const auto *RHS = BinOp->getRHS()->IgnoreParenImpCasts();
// <expr> & <mask>, mask is a compile time constant.
Expr::EvalResult RHSVal;
if (BinOp->getOpcode() == BO_And &&
(RHS->EvaluateAsInt(RHSVal, Ctx, Expr::SE_AllowSideEffects) ||
LHS->EvaluateAsInt(RHSVal, Ctx, Expr::SE_AllowSideEffects)))
return true;
// <char literal> + (<expr> % <mod>), where <base> is a char literal.
const auto IsCharPlusModExpr = [](const Expr *L, const Expr *R) {
const auto *ROp = dyn_cast<BinaryOperator>(R);
return ROp && ROp->getOpcode() == BO_Rem && isa<CharacterLiteral>(L);
};
if (BinOp->getOpcode() == BO_Add) {
if (IsCharPlusModExpr(LHS, RHS) || IsCharPlusModExpr(RHS, LHS))
return true;
}
return false;
}
void StringIntegerAssignmentCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *Argument = Result.Nodes.getNodeAs<Expr>("expr");
SourceLocation Loc = Argument->getBeginLoc();
// Try to detect a few common expressions to reduce false positives.
if (isLikelyCharExpression(Argument, *Result.Context))
return;
auto Diag =
diag(Loc, "an integer is interpreted as a character code when assigning "
"it to a string; if this is intended, cast the integer to the "
"appropriate character type; if you want a string "
"representation, use the appropriate conversion facility");
if (Loc.isMacroID())
return;
auto CharType = *Result.Nodes.getNodeAs<QualType>("type");
bool IsWideCharType = CharType->isWideCharType();
if (!CharType->isCharType() && !IsWideCharType)
return;
bool IsOneDigit = false;
bool IsLiteral = false;
if (const auto *Literal = dyn_cast<IntegerLiteral>(Argument)) {
IsOneDigit = Literal->getValue().getLimitedValue() < 10;
IsLiteral = true;
}
SourceLocation EndLoc = Lexer::getLocForEndOfToken(
Argument->getEndLoc(), 0, *Result.SourceManager, getLangOpts());
if (IsOneDigit) {
Diag << FixItHint::CreateInsertion(Loc, IsWideCharType ? "L'" : "'")
<< FixItHint::CreateInsertion(EndLoc, "'");
return;
}
if (IsLiteral) {
Diag << FixItHint::CreateInsertion(Loc, IsWideCharType ? "L\"" : "\"")
<< FixItHint::CreateInsertion(EndLoc, "\"");
return;
}
if (getLangOpts().CPlusPlus11) {
Diag << FixItHint::CreateInsertion(Loc, IsWideCharType ? "std::to_wstring("
: "std::to_string(")
<< FixItHint::CreateInsertion(EndLoc, ")");
}
}
} // namespace bugprone
} // namespace tidy
} // namespace clang
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