1 //===--- PreferIsaOrDynCastInConditionalsCheck.cpp - clang-tidy
2 //---------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "PreferIsaOrDynCastInConditionalsCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Lex/Lexer.h"
14
15 using namespace clang::ast_matchers;
16
17 namespace clang {
18 namespace ast_matchers {
AST_MATCHER(Expr,isMacroID)19 AST_MATCHER(Expr, isMacroID) { return Node.getExprLoc().isMacroID(); }
20 } // namespace ast_matchers
21
22 namespace tidy::llvm_check {
23
registerMatchers(MatchFinder * Finder)24 void PreferIsaOrDynCastInConditionalsCheck::registerMatchers(
25 MatchFinder *Finder) {
26 auto Condition = hasCondition(implicitCastExpr(has(
27 callExpr(unless(isMacroID()), unless(cxxMemberCallExpr()),
28 anyOf(callee(namedDecl(hasName("cast"))),
29 callee(namedDecl(hasName("dyn_cast")).bind("dyn_cast"))))
30 .bind("call"))));
31
32 auto Any = anyOf(
33 has(declStmt(containsDeclaration(
34 0, varDecl(hasInitializer(callExpr(unless(isMacroID()),
35 unless(cxxMemberCallExpr()),
36 callee(namedDecl(hasName("cast"))))
37 .bind("assign")))))),
38 Condition);
39
40 auto CallExpression =
41 callExpr(
42
43 unless(isMacroID()), unless(cxxMemberCallExpr()),
44 callee(namedDecl(hasAnyName("isa", "cast", "cast_or_null", "dyn_cast",
45 "dyn_cast_or_null"))
46 .bind("func")),
47 hasArgument(0, mapAnyOf(declRefExpr, cxxMemberCallExpr).bind("arg")))
48 .bind("rhs");
49
50 Finder->addMatcher(
51 traverse(
52 TK_AsIs,
53 stmt(anyOf(
54 ifStmt(Any), whileStmt(Any), doStmt(Condition),
55 binaryOperator(unless(isExpansionInFileMatching(
56 "llvm/include/llvm/Support/Casting.h")),
57 hasOperatorName("&&"),
58 hasLHS(implicitCastExpr().bind("lhs")),
59 hasRHS(anyOf(implicitCastExpr(has(CallExpression)),
60 CallExpression)))
61 .bind("and")))),
62 this);
63 }
64
check(const MatchFinder::MatchResult & Result)65 void PreferIsaOrDynCastInConditionalsCheck::check(
66 const MatchFinder::MatchResult &Result) {
67 if (const auto *MatchedDecl = Result.Nodes.getNodeAs<CallExpr>("assign")) {
68 SourceLocation StartLoc = MatchedDecl->getCallee()->getExprLoc();
69 SourceLocation EndLoc =
70 StartLoc.getLocWithOffset(StringRef("cast").size() - 1);
71
72 diag(MatchedDecl->getBeginLoc(),
73 "cast<> in conditional will assert rather than return a null pointer")
74 << FixItHint::CreateReplacement(SourceRange(StartLoc, EndLoc),
75 "dyn_cast");
76 } else if (const auto *MatchedDecl =
77 Result.Nodes.getNodeAs<CallExpr>("call")) {
78 SourceLocation StartLoc = MatchedDecl->getCallee()->getExprLoc();
79 SourceLocation EndLoc =
80 StartLoc.getLocWithOffset(StringRef("cast").size() - 1);
81
82 StringRef Message =
83 "cast<> in conditional will assert rather than return a null pointer";
84 if (Result.Nodes.getNodeAs<NamedDecl>("dyn_cast"))
85 Message = "return value from dyn_cast<> not used";
86
87 diag(MatchedDecl->getBeginLoc(), Message)
88 << FixItHint::CreateReplacement(SourceRange(StartLoc, EndLoc), "isa");
89 } else if (const auto *MatchedDecl =
90 Result.Nodes.getNodeAs<BinaryOperator>("and")) {
91 const auto *LHS = Result.Nodes.getNodeAs<ImplicitCastExpr>("lhs");
92 const auto *RHS = Result.Nodes.getNodeAs<CallExpr>("rhs");
93 const auto *Arg = Result.Nodes.getNodeAs<Expr>("arg");
94 const auto *Func = Result.Nodes.getNodeAs<NamedDecl>("func");
95
96 assert(LHS && "LHS is null");
97 assert(RHS && "RHS is null");
98 assert(Arg && "Arg is null");
99 assert(Func && "Func is null");
100
101 StringRef LHSString(Lexer::getSourceText(
102 CharSourceRange::getTokenRange(LHS->getSourceRange()),
103 *Result.SourceManager, getLangOpts()));
104
105 StringRef ArgString(Lexer::getSourceText(
106 CharSourceRange::getTokenRange(Arg->getSourceRange()),
107 *Result.SourceManager, getLangOpts()));
108
109 if (ArgString != LHSString)
110 return;
111
112 StringRef RHSString(Lexer::getSourceText(
113 CharSourceRange::getTokenRange(RHS->getSourceRange()),
114 *Result.SourceManager, getLangOpts()));
115
116 std::string Replacement("isa_and_nonnull");
117 Replacement += RHSString.substr(Func->getName().size());
118
119 diag(MatchedDecl->getBeginLoc(),
120 "isa_and_nonnull<> is preferred over an explicit test for null "
121 "followed by calling isa<>")
122 << FixItHint::CreateReplacement(SourceRange(MatchedDecl->getBeginLoc(),
123 MatchedDecl->getEndLoc()),
124 Replacement);
125 }
126 }
127
128 } // namespace tidy::llvm_check
129 } // namespace clang
130