[clang-tidy] New checker to detect suspicious string constructor.
Summary: Checker to validate string constructor parameters. A common mistake is to swap parameter for the fill-constructor. ``` std::string str('x', 4); std::string str('4', x); ``` Reviewers: alexfh Subscribers: cfe-commits Differential Revision: http://reviews.llvm.org/D19146 llvm-svn: 267011
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@ -25,6 +25,7 @@ add_clang_library(clangTidyMiscModule
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SizeofContainerCheck.cpp
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SizeofExpressionCheck.cpp
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StaticAssertCheck.cpp
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StringConstructorCheck.cpp
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StringIntegerAssignmentCheck.cpp
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StringLiteralWithEmbeddedNulCheck.cpp
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SuspiciousMissingCommaCheck.cpp
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@ -33,6 +33,7 @@
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#include "SizeofContainerCheck.h"
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#include "SizeofExpressionCheck.h"
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#include "StaticAssertCheck.h"
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#include "StringConstructorCheck.h"
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#include "StringIntegerAssignmentCheck.h"
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#include "StringLiteralWithEmbeddedNulCheck.h"
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#include "SuspiciousMissingCommaCheck.h"
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@ -99,6 +100,8 @@ public:
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"misc-sizeof-expression");
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CheckFactories.registerCheck<StaticAssertCheck>(
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"misc-static-assert");
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CheckFactories.registerCheck<StringConstructorCheck>(
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"misc-string-constructor");
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CheckFactories.registerCheck<StringIntegerAssignmentCheck>(
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"misc-string-integer-assignment");
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CheckFactories.registerCheck<StringLiteralWithEmbeddedNulCheck>(
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@ -0,0 +1,126 @@
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//===--- StringConstructorCheck.cpp - clang-tidy---------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "StringConstructorCheck.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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using namespace clang::ast_matchers;
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namespace clang {
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namespace tidy {
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namespace misc {
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AST_MATCHER_P(IntegerLiteral, isBiggerThan, unsigned, N) {
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return Node.getValue().getZExtValue() > N;
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}
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StringConstructorCheck::StringConstructorCheck(StringRef Name,
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ClangTidyContext *Context)
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: ClangTidyCheck(Name, Context),
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WarnOnLargeLength(Options.get("WarnOnLargeLength", 1) != 0),
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LargeLengthThreshold(Options.get("LargeLengthThreshold", 0x800000)) {}
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void StringConstructorCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
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Options.store(Opts, "WarnOnLargeLength", WarnOnLargeLength);
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Options.store(Opts, "LargeLengthThreshold", LargeLengthThreshold);
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}
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void StringConstructorCheck::registerMatchers(MatchFinder *Finder) {
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if (!getLangOpts().CPlusPlus)
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return;
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const auto ZeroExpr = expr(ignoringParenImpCasts(integerLiteral(equals(0))));
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const auto CharExpr = expr(ignoringParenImpCasts(characterLiteral()));
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const auto NegativeExpr = expr(ignoringParenImpCasts(
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unaryOperator(hasOperatorName("-"),
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hasUnaryOperand(integerLiteral(unless(equals(0)))))));
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const auto LargeLengthExpr = expr(ignoringParenImpCasts(
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integerLiteral(isBiggerThan(LargeLengthThreshold))));
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const auto CharPtrType = type(anyOf(pointerType(), arrayType()));
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// Match a string-literal; even through a declaration with initializer.
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const auto BoundStringLiteral = stringLiteral().bind("str");
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const auto ConstStrLiteralDecl = varDecl(
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isDefinition(), hasType(constantArrayType()), hasType(isConstQualified()),
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hasInitializer(ignoringParenImpCasts(BoundStringLiteral)));
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const auto ConstPtrStrLiteralDecl = varDecl(
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isDefinition(),
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hasType(pointerType(pointee(isAnyCharacter(), isConstQualified()))),
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hasInitializer(ignoringParenImpCasts(BoundStringLiteral)));
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auto ConstStrLiteral = expr(ignoringParenImpCasts(anyOf(
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BoundStringLiteral, declRefExpr(hasDeclaration(anyOf(
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ConstPtrStrLiteralDecl, ConstStrLiteralDecl))))));
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// Check the fill constructor. Fills the string with n consecutive copies of
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// character c. [i.e string(size_t n, char c);].
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Finder->addMatcher(
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cxxConstructExpr(
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hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
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hasArgument(0, hasType(qualType(isInteger()))),
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hasArgument(1, hasType(qualType(isInteger()))),
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anyOf(
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// Detect the expression: string('x', 40);
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hasArgument(0, CharExpr.bind("swapped-parameter")),
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// Detect the expression: string(0, ...);
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hasArgument(0, ZeroExpr.bind("empty-string")),
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// Detect the expression: string(-4, ...);
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hasArgument(0, NegativeExpr.bind("negative-length")),
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// Detect the expression: string(0x1234567, ...);
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hasArgument(0, LargeLengthExpr.bind("large-length"))))
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.bind("constructor"),
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this);
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// Check the literal string constructor with char pointer and length
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// parameters. [i.e. string (const char* s, size_t n);]
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Finder->addMatcher(
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cxxConstructExpr(
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hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
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hasArgument(0, hasType(CharPtrType)),
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hasArgument(1, hasType(isInteger())),
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anyOf(
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// Detect the expression: string("...", 0);
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hasArgument(1, ZeroExpr.bind("empty-string")),
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// Detect the expression: string("...", -4);
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hasArgument(1, NegativeExpr.bind("negative-length")),
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// Detect the expression: string("lit", 0x1234567);
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hasArgument(1, LargeLengthExpr.bind("large-length")),
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// Detect the expression: string("lit", 5)
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allOf(hasArgument(0, ConstStrLiteral.bind("literal-with-length")),
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hasArgument(1, ignoringParenImpCasts(
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integerLiteral().bind("int"))))))
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.bind("constructor"),
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this);
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}
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void StringConstructorCheck::check(const MatchFinder::MatchResult &Result) {
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const auto *E = Result.Nodes.getNodeAs<Expr>("constructor");
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SourceLocation Loc = E->getLocStart();
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if (Result.Nodes.getNodeAs<Expr>("swapped-parameter")) {
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diag(Loc, "constructor parameters are probably swapped");
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} else if (Result.Nodes.getNodeAs<Expr>("empty-string")) {
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diag(Loc, "constructor creating an empty string");
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} else if (Result.Nodes.getNodeAs<Expr>("negative-length")) {
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diag(Loc, "negative value used as length parameter");
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} else if (Result.Nodes.getNodeAs<Expr>("large-length")) {
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if (WarnOnLargeLength)
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diag(Loc, "suspicious large length parameter");
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} else if (Result.Nodes.getNodeAs<Expr>("literal-with-length")) {
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const auto *Str = Result.Nodes.getNodeAs<StringLiteral>("str");
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const auto *Lit = Result.Nodes.getNodeAs<IntegerLiteral>("int");
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if (Lit->getValue().ugt(Str->getLength())) {
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diag(Loc, "length is bigger then string literal size");
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}
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}
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}
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} // namespace misc
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} // namespace tidy
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} // namespace clang
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@ -0,0 +1,39 @@
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//===--- StringConstructorCheck.h - clang-tidy-------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_STRING_CONSTRUCTOR_H
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#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_STRING_CONSTRUCTOR_H
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#include "../ClangTidy.h"
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namespace clang {
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namespace tidy {
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namespace misc {
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/// Finds suspicious string constructor and check their parameters.
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///
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/// For the user-facing documentation see:
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/// http://clang.llvm.org/extra/clang-tidy/checks/misc-string-constructor.html
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class StringConstructorCheck : public ClangTidyCheck {
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public:
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StringConstructorCheck(StringRef Name, ClangTidyContext *Context);
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void storeOptions(ClangTidyOptions::OptionMap &Opts);
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void registerMatchers(ast_matchers::MatchFinder *Finder) override;
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void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
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private:
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const bool WarnOnLargeLength;
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const unsigned int LargeLengthThreshold;
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};
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} // namespace misc
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} // namespace tidy
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} // namespace clang
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#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_STRING_CONSTRUCTOR_H
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@ -69,6 +69,7 @@ Clang-Tidy Checks
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misc-sizeof-container
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misc-sizeof-expression
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misc-static-assert
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misc-string-constructor
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misc-string-integer-assignment
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misc-string-literal-with-embedded-nul
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misc-suspicious-missing-comma
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@ -0,0 +1,36 @@
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.. title:: clang-tidy - misc-string-constructor
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misc-string-constructor
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=======================
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Finds string constructors that are suspicious and probably errors.
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A common mistake is to swap parameters to the 'fill' string-constructor.
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Examples:
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.. code:: c++
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std::string('x', 50) str; // should be std::string(50, 'x')
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Calling the string-literal constructor with a length bigger than the literal is
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suspicious and adds extra random characters to the string.
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Examples:
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.. code:: c++
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std::string("test", 200); // Will include random characters after "test".
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Creating an empty string from constructors with parameters is considered
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suspicious. The programmer should use the empty constructor instead.
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Examples:
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.. code:: c++
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std::string("test", 0); // Creation of an empty string.
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@ -0,0 +1,54 @@
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// RUN: %check_clang_tidy %s misc-string-constructor %t
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namespace std {
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template <typename T>
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class allocator {};
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template <typename T>
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class char_traits {};
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template <typename C, typename T = std::char_traits<C>, typename A = std::allocator<C> >
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struct basic_string {
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basic_string();
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basic_string(const C*, unsigned int size);
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basic_string(unsigned int size, C c);
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};
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typedef basic_string<char> string;
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typedef basic_string<wchar_t> wstring;
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}
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const char* kText = "";
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const char kText2[] = "";
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extern const char kText3[];
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void Test() {
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std::string str('x', 4);
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: constructor parameters are probably swapped [misc-string-constructor]
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std::wstring wstr(L'x', 4);
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// CHECK-MESSAGES: [[@LINE-1]]:16: warning: constructor parameters are probably swapped
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std::string s0(0, 'x');
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: constructor creating an empty string
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std::string s1(-4, 'x');
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: negative value used as length parameter
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std::string s2(0x1000000, 'x');
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: suspicious large length parameter
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std::string q0("test", 0);
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: constructor creating an empty string
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std::string q1(kText, -4);
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: negative value used as length parameter
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std::string q2("test", 200);
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: length is bigger then string literal size
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std::string q3(kText, 200);
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: length is bigger then string literal size
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std::string q4(kText2, 200);
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: length is bigger then string literal size
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std::string q5(kText3, 0x1000000);
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// CHECK-MESSAGES: [[@LINE-1]]:15: warning: suspicious large length parameter
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}
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void Valid() {
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std::string empty();
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std::string str(4, 'x');
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std::wstring wstr(4, L'x');
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std::string s1("test", 4);
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std::string s2("test", 3);
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}
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