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StaticAssertCheck.cpp
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1 //===--- StaticAssertCheck.cpp - clang-tidy -------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "StaticAssertCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/Expr.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 <string>
20
21 using namespace clang::ast_matchers;
22
23 namespace clang {
24 namespace tidy {
25
26 StaticAssertCheck::StaticAssertCheck(StringRef Name, ClangTidyContext *Context)
27 : ClangTidyCheck(Name, Context) {}
28
29 void StaticAssertCheck::registerMatchers(MatchFinder *Finder) {
30 // This checker only makes sense for languages that have static assertion
31 // capabilities: C++11 and C11.
32 if (!(getLangOpts().CPlusPlus11 || getLangOpts().C11))
33 return;
34
35 auto IsAlwaysFalse = expr(ignoringParenImpCasts(
36 expr(anyOf(cxxBoolLiteral(equals(false)), integerLiteral(equals(0)),
37 cxxNullPtrLiteralExpr(), gnuNullExpr()))
38 .bind("isAlwaysFalse")));
39 auto IsAlwaysFalseWithCast = ignoringParenImpCasts(anyOf(
40 IsAlwaysFalse, cStyleCastExpr(has(IsAlwaysFalse)).bind("castExpr")));
41 auto AssertExprRoot = anyOf(
42 binaryOperator(
43 anyOf(hasOperatorName("&&"), hasOperatorName("==")),
44 hasEitherOperand(ignoringImpCasts(stringLiteral().bind("assertMSG"))),
45 anyOf(binaryOperator(hasEitherOperand(IsAlwaysFalseWithCast)),
46 anything()))
47 .bind("assertExprRoot"),
48 IsAlwaysFalse);
49 auto NonConstexprFunctionCall =
50 callExpr(hasDeclaration(functionDecl(unless(isConstexpr()))));
51 auto AssertCondition =
52 expr(
53 anyOf(expr(ignoringParenCasts(anyOf(
54 AssertExprRoot, unaryOperator(hasUnaryOperand(
55 ignoringParenCasts(AssertExprRoot)))))),
56 anything()),
57 unless(findAll(NonConstexprFunctionCall)))
58 .bind("condition");
59 auto Condition =
60 anyOf(ignoringParenImpCasts(callExpr(
61 hasDeclaration(functionDecl(hasName("__builtin_expect"))),
62 hasArgument(0, AssertCondition))),
63 AssertCondition);
64
65 Finder->addMatcher(stmt(anyOf(conditionalOperator(hasCondition(Condition)),
66 ifStmt(hasCondition(Condition))),
67 unless(isInTemplateInstantiation()))
68 .bind("condStmt"),
69 this);
70 }
71
72 void StaticAssertCheck::check(const MatchFinder::MatchResult &Result) {
73 const ASTContext *ASTCtx = Result.Context;
74 const LangOptions &Opts = ASTCtx->getLangOpts();
75 const SourceManager &SM = ASTCtx->getSourceManager();
76 const auto *CondStmt = Result.Nodes.getNodeAs<Stmt>("condStmt");
77 const auto *Condition = Result.Nodes.getNodeAs<Expr>("condition");
78 const auto *IsAlwaysFalse = Result.Nodes.getNodeAs<Expr>("isAlwaysFalse");
79 const auto *AssertMSG = Result.Nodes.getNodeAs<StringLiteral>("assertMSG");
80 const auto *AssertExprRoot =
81 Result.Nodes.getNodeAs<BinaryOperator>("assertExprRoot");
82 const auto *CastExpr = Result.Nodes.getNodeAs<CStyleCastExpr>("castExpr");
83 SourceLocation AssertExpansionLoc = CondStmt->getLocStart();
84
85 if (!AssertExpansionLoc.isValid() || !AssertExpansionLoc.isMacroID())
86 return;
87
88 StringRef MacroName =
89 Lexer::getImmediateMacroName(AssertExpansionLoc, SM, Opts);
90
91 if (MacroName != "assert" || Condition->isValueDependent() ||
92 Condition->isTypeDependent() || Condition->isInstantiationDependent() ||
93 !Condition->isEvaluatable(*ASTCtx))
94 return;
95
96 // False literal is not the result of macro expansion.
97 if (IsAlwaysFalse && (!CastExpr || CastExpr->getType()->isPointerType())) {
98 SourceLocation FalseLiteralLoc =
99 SM.getImmediateSpellingLoc(IsAlwaysFalse->getExprLoc());
100 if (!FalseLiteralLoc.isMacroID())
101 return;
102
103 StringRef FalseMacroName =
104 Lexer::getImmediateMacroName(FalseLiteralLoc, SM, Opts);
105 if (FalseMacroName.compare_lower("false") == 0 ||
106 FalseMacroName.compare_lower("null") == 0)
107 return;
108 }
109
110 SourceLocation AssertLoc = SM.getImmediateMacroCallerLoc(AssertExpansionLoc);
111
112 SmallVector<FixItHint, 4> FixItHints;
113 SourceLocation LastParenLoc;
114 if (AssertLoc.isValid() && !AssertLoc.isMacroID() &&
115 (LastParenLoc = getLastParenLoc(ASTCtx, AssertLoc)).isValid()) {
116 FixItHints.push_back(
117 FixItHint::CreateReplacement(SourceRange(AssertLoc), "static_assert"));
118
119 std::string StaticAssertMSG = ", \"\"";
120 if (AssertExprRoot) {
121 FixItHints.push_back(FixItHint::CreateRemoval(
122 SourceRange(AssertExprRoot->getOperatorLoc())));
123 FixItHints.push_back(FixItHint::CreateRemoval(
124 SourceRange(AssertMSG->getLocStart(), AssertMSG->getLocEnd())));
125 StaticAssertMSG = (Twine(", \"") + AssertMSG->getString() + "\"").str();
126 }
127
128 FixItHints.push_back(
129 FixItHint::CreateInsertion(LastParenLoc, StaticAssertMSG));
130 }
131
132 diag(AssertLoc, "found assert() that could be replaced by static_assert()")
133 << FixItHints;
134 }
135
136 SourceLocation StaticAssertCheck::getLastParenLoc(const ASTContext *ASTCtx,
137 SourceLocation AssertLoc) {
138 const LangOptions &Opts = ASTCtx->getLangOpts();
139 const SourceManager &SM = ASTCtx->getSourceManager();
140
141 llvm::MemoryBuffer *Buffer = SM.getBuffer(SM.getFileID(AssertLoc));
142 if (!Buffer)
143 return SourceLocation();
144
145 const char *BufferPos = SM.getCharacterData(AssertLoc);
146
147 Token Token;
148 Lexer Lexer(SM.getLocForStartOfFile(SM.getFileID(AssertLoc)), Opts,
149 Buffer->getBufferStart(), BufferPos, Buffer->getBufferEnd());
150
151 // assert first left parenthesis
152 if (Lexer.LexFromRawLexer(Token) || Lexer.LexFromRawLexer(Token) ||
153 !Token.is(tok::l_paren))
154 return SourceLocation();
155
156 unsigned int ParenCount = 1;
157 while (ParenCount && !Lexer.LexFromRawLexer(Token)) {
158 if (Token.is(tok::l_paren))
159 ++ParenCount;
160 else if (Token.is(tok::r_paren))
161 --ParenCount;
162 }
163
164 return Token.getLocation();
165 }
166
167 } // namespace tidy
168 } // namespace clang
clang::tidy::ClangTidyCheck::getLangOpts
LangOptions getLangOpts() const
Returns the language options from the context.
Definition: ClangTidy.h:162
StaticAssertCheck.h
Name
StringHandle Name
Definition: PreprocessorTracker.cpp:525
Finder
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:188
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidy.h:102
clang::tidy::StaticAssertCheck::registerMatchers
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register ASTMatchers with Finder.
Definition: StaticAssertCheck.cpp:29
SM
SourceManager & SM
Definition: IncludeOrderCheck.cpp:44
clang::tidy::StaticAssertCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: StaticAssertCheck.cpp:72
Context
ClangTidyContext & Context
Definition: ClangTidy.cpp:93
clang::tidy::ClangTidyContext
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
Definition: ClangTidyDiagnosticConsumer.h:124
clang::tidy::ClangTidyCheck::diag
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Definition: ClangTidy.cpp:323
Result
const NamedDecl * Result
Definition: USRFinder.cpp:121