1 //===--- AssertSideEffectCheck.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 "AssertSideEffectCheck.h"
10 #include "../utils/Matchers.h"
11 #include "../utils/OptionsUtils.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 #include "clang/Frontend/CompilerInstance.h"
15 #include "clang/Lex/Lexer.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/Support/Casting.h"
19 #include <algorithm>
20 #include <string>
21
22 using namespace clang::ast_matchers;
23
24 namespace clang::tidy::bugprone {
25
26 namespace {
27
AST_MATCHER_P2(Expr,hasSideEffect,bool,CheckFunctionCalls,clang::ast_matchers::internal::Matcher<NamedDecl>,IgnoredFunctionsMatcher)28 AST_MATCHER_P2(Expr, hasSideEffect, bool, CheckFunctionCalls,
29 clang::ast_matchers::internal::Matcher<NamedDecl>,
30 IgnoredFunctionsMatcher) {
31 const Expr *E = &Node;
32
33 if (const auto *Op = dyn_cast<UnaryOperator>(E)) {
34 UnaryOperator::Opcode OC = Op->getOpcode();
35 return OC == UO_PostInc || OC == UO_PostDec || OC == UO_PreInc ||
36 OC == UO_PreDec;
37 }
38
39 if (const auto *Op = dyn_cast<BinaryOperator>(E)) {
40 return Op->isAssignmentOp();
41 }
42
43 if (const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
44 if (const auto *MethodDecl =
45 dyn_cast_or_null<CXXMethodDecl>(OpCallExpr->getDirectCallee()))
46 if (MethodDecl->isConst())
47 return false;
48
49 OverloadedOperatorKind OpKind = OpCallExpr->getOperator();
50 return OpKind == OO_Equal || OpKind == OO_PlusEqual ||
51 OpKind == OO_MinusEqual || OpKind == OO_StarEqual ||
52 OpKind == OO_SlashEqual || OpKind == OO_AmpEqual ||
53 OpKind == OO_PipeEqual || OpKind == OO_CaretEqual ||
54 OpKind == OO_LessLessEqual || OpKind == OO_GreaterGreaterEqual ||
55 OpKind == OO_LessLess || OpKind == OO_GreaterGreater ||
56 OpKind == OO_PlusPlus || OpKind == OO_MinusMinus ||
57 OpKind == OO_PercentEqual || OpKind == OO_New ||
58 OpKind == OO_Delete || OpKind == OO_Array_New ||
59 OpKind == OO_Array_Delete;
60 }
61
62 if (const auto *CExpr = dyn_cast<CallExpr>(E)) {
63 if (!CheckFunctionCalls)
64 return false;
65 if (const auto *FuncDecl = CExpr->getDirectCallee()) {
66 if (FuncDecl->getDeclName().isIdentifier() &&
67 IgnoredFunctionsMatcher.matches(*FuncDecl, Finder,
68 Builder)) // exceptions come here
69 return false;
70 for (size_t I = 0; I < FuncDecl->getNumParams(); I++) {
71 const ParmVarDecl *P = FuncDecl->getParamDecl(I);
72 const Expr *ArgExpr =
73 I < CExpr->getNumArgs() ? CExpr->getArg(I) : nullptr;
74 const QualType PT = P->getType().getCanonicalType();
75 if (ArgExpr && !ArgExpr->isXValue() && PT->isReferenceType() &&
76 !PT.getNonReferenceType().isConstQualified())
77 return true;
78 }
79 if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
80 return !MethodDecl->isConst();
81 }
82 return true;
83 }
84
85 return isa<CXXNewExpr>(E) || isa<CXXDeleteExpr>(E) || isa<CXXThrowExpr>(E);
86 }
87
88 } // namespace
89
AssertSideEffectCheck(StringRef Name,ClangTidyContext * Context)90 AssertSideEffectCheck::AssertSideEffectCheck(StringRef Name,
91 ClangTidyContext *Context)
92 : ClangTidyCheck(Name, Context),
93 CheckFunctionCalls(Options.get("CheckFunctionCalls", false)),
94 RawAssertList(Options.get("AssertMacros", "assert,NSAssert,NSCAssert")),
95 IgnoredFunctions(utils::options::parseListPair(
96 "__builtin_expect;", Options.get("IgnoredFunctions", ""))) {
97 StringRef(RawAssertList).split(AssertMacros, ",", -1, false);
98 }
99
100 // The options are explained in AssertSideEffectCheck.h.
storeOptions(ClangTidyOptions::OptionMap & Opts)101 void AssertSideEffectCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
102 Options.store(Opts, "CheckFunctionCalls", CheckFunctionCalls);
103 Options.store(Opts, "AssertMacros", RawAssertList);
104 Options.store(Opts, "IgnoredFunctions",
105 utils::options::serializeStringList(IgnoredFunctions));
106 }
107
registerMatchers(MatchFinder * Finder)108 void AssertSideEffectCheck::registerMatchers(MatchFinder *Finder) {
109 auto IgnoredFunctionsMatcher =
110 matchers::matchesAnyListedName(IgnoredFunctions);
111
112 auto DescendantWithSideEffect =
113 traverse(TK_AsIs, hasDescendant(expr(hasSideEffect(
114 CheckFunctionCalls, IgnoredFunctionsMatcher))));
115 auto ConditionWithSideEffect = hasCondition(DescendantWithSideEffect);
116 Finder->addMatcher(
117 stmt(
118 anyOf(conditionalOperator(ConditionWithSideEffect),
119 ifStmt(ConditionWithSideEffect),
120 unaryOperator(hasOperatorName("!"),
121 hasUnaryOperand(unaryOperator(
122 hasOperatorName("!"),
123 hasUnaryOperand(DescendantWithSideEffect))))))
124 .bind("condStmt"),
125 this);
126 }
127
check(const MatchFinder::MatchResult & Result)128 void AssertSideEffectCheck::check(const MatchFinder::MatchResult &Result) {
129 const SourceManager &SM = *Result.SourceManager;
130 const LangOptions LangOpts = getLangOpts();
131 SourceLocation Loc = Result.Nodes.getNodeAs<Stmt>("condStmt")->getBeginLoc();
132
133 StringRef AssertMacroName;
134 while (Loc.isValid() && Loc.isMacroID()) {
135 StringRef MacroName = Lexer::getImmediateMacroName(Loc, SM, LangOpts);
136 Loc = SM.getImmediateMacroCallerLoc(Loc);
137
138 // Check if this macro is an assert.
139 if (llvm::is_contained(AssertMacros, MacroName)) {
140 AssertMacroName = MacroName;
141 break;
142 }
143 }
144 if (AssertMacroName.empty())
145 return;
146
147 diag(Loc, "side effect in %0() condition discarded in release builds")
148 << AssertMacroName;
149 }
150
151 } // namespace clang::tidy::bugprone
152