1//===--- PosixReturnCheck.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 "PosixReturnCheck.h"
10#include "clang/AST/ASTContext.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::bugprone {
18
19static StringRef getFunctionSpelling(const MatchFinder::MatchResult &Result) {
20 const auto *MatchedCall = Result.Nodes.getNodeAs<CallExpr>(ID: "call");
21 const SourceManager &SM = *Result.SourceManager;
22 return Lexer::getSourceText(Range: CharSourceRange::getTokenRange(
23 MatchedCall->getCallee()->getSourceRange()),
24 SM, LangOpts: Result.Context->getLangOpts());
25}
26
27void PosixReturnCheck::registerMatchers(MatchFinder *Finder) {
28 const auto PosixCall =
29 callExpr(callee(InnerMatcher: functionDecl(
30 anyOf(matchesName(RegExp: "^::posix_"), matchesName(RegExp: "^::pthread_")),
31 unless(hasName(Name: "::posix_openpt")))))
32 .bind(ID: "call");
33 const auto ZeroIntegerLiteral = integerLiteral(equals(Value: 0));
34 const auto NegIntegerLiteral =
35 unaryOperator(hasOperatorName(Name: "-"), hasUnaryOperand(InnerMatcher: integerLiteral()));
36
37 Finder->addMatcher(
38 NodeMatch: binaryOperator(
39 anyOf(allOf(hasOperatorName(Name: "<"), hasLHS(InnerMatcher: PosixCall),
40 hasRHS(InnerMatcher: ZeroIntegerLiteral)),
41 allOf(hasOperatorName(Name: ">"), hasLHS(InnerMatcher: ZeroIntegerLiteral),
42 hasRHS(InnerMatcher: PosixCall))))
43 .bind(ID: "ltzop"),
44 Action: this);
45 Finder->addMatcher(
46 NodeMatch: binaryOperator(
47 anyOf(allOf(hasOperatorName(Name: ">="), hasLHS(InnerMatcher: PosixCall),
48 hasRHS(InnerMatcher: ZeroIntegerLiteral)),
49 allOf(hasOperatorName(Name: "<="), hasLHS(InnerMatcher: ZeroIntegerLiteral),
50 hasRHS(InnerMatcher: PosixCall))))
51 .bind(ID: "atop"),
52 Action: this);
53 Finder->addMatcher(NodeMatch: binaryOperator(hasAnyOperatorName("==", "!="),
54 hasOperands(Matcher1: PosixCall, Matcher2: NegIntegerLiteral))
55 .bind(ID: "binop"),
56 Action: this);
57 Finder->addMatcher(
58 NodeMatch: binaryOperator(anyOf(allOf(hasAnyOperatorName("<=", "<"),
59 hasLHS(InnerMatcher: PosixCall), hasRHS(InnerMatcher: NegIntegerLiteral)),
60 allOf(hasAnyOperatorName(">", ">="),
61 hasLHS(InnerMatcher: NegIntegerLiteral), hasRHS(InnerMatcher: PosixCall))))
62 .bind(ID: "binop"),
63 Action: this);
64}
65
66void PosixReturnCheck::check(const MatchFinder::MatchResult &Result) {
67 if (const auto *LessThanZeroOp =
68 Result.Nodes.getNodeAs<BinaryOperator>(ID: "ltzop")) {
69 SourceLocation OperatorLoc = LessThanZeroOp->getOperatorLoc();
70 StringRef NewBinOp =
71 LessThanZeroOp->getOpcode() == BinaryOperator::Opcode::BO_LT ? ">"
72 : "<";
73 diag(Loc: OperatorLoc, Description: "the comparison always evaluates to false because %0 "
74 "always returns non-negative values")
75 << getFunctionSpelling(Result)
76 << FixItHint::CreateReplacement(RemoveRange: OperatorLoc, Code: NewBinOp);
77 return;
78 }
79 if (const auto *AlwaysTrueOp =
80 Result.Nodes.getNodeAs<BinaryOperator>(ID: "atop")) {
81 diag(Loc: AlwaysTrueOp->getOperatorLoc(),
82 Description: "the comparison always evaluates to true because %0 always returns "
83 "non-negative values")
84 << getFunctionSpelling(Result);
85 return;
86 }
87 const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>(ID: "binop");
88 diag(Loc: BinOp->getOperatorLoc(), Description: "%0 only returns non-negative values")
89 << getFunctionSpelling(Result);
90}
91
92} // namespace clang::tidy::bugprone
93

source code of clang-tools-extra/clang-tidy/bugprone/PosixReturnCheck.cpp