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[clang-tidy][modernize-use-starts-ends-with] Add support for two ends_with patterns #105366

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226 changes: 135 additions & 91 deletions clang-tools-extra/clang-tidy/modernize/UseStartsEndsWithCheck.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@

#include "UseStartsEndsWithCheck.h"

#include "../utils/ASTUtils.h"
#include "../utils/OptionsUtils.h"
#include "clang/Lex/Lexer.h"

Expand All @@ -16,13 +17,71 @@
using namespace clang::ast_matchers;

namespace clang::tidy::modernize {
struct NotLengthExprForStringNode {
NotLengthExprForStringNode(std::string ID, DynTypedNode Node,
ASTContext *Context)
: ID(std::move(ID)), Node(std::move(Node)), Context(Context) {}
bool operator()(const internal::BoundNodesMap &Nodes) const {
// Match a string literal and an integer size or strlen() call.
if (const auto *StringLiteralNode = Nodes.getNodeAs<StringLiteral>(ID)) {
if (const auto *IntegerLiteralSizeNode = Node.get<IntegerLiteral>()) {
return StringLiteralNode->getLength() !=
IntegerLiteralSizeNode->getValue().getZExtValue();
}

if (const auto *StrlenNode = Node.get<CallExpr>()) {
if (StrlenNode->getDirectCallee()->getName() != "strlen" ||
StrlenNode->getNumArgs() != 1) {
return true;
}

if (const auto *StrlenArgNode = dyn_cast<StringLiteral>(
StrlenNode->getArg(0)->IgnoreParenImpCasts())) {
return StrlenArgNode->getLength() != StringLiteralNode->getLength();
}
}
}

// Match a string variable and a call to length() or size().
if (const auto *ExprNode = Nodes.getNodeAs<Expr>(ID)) {
if (const auto *MemberCallNode = Node.get<CXXMemberCallExpr>()) {
const CXXMethodDecl *MethodDeclNode = MemberCallNode->getMethodDecl();
const StringRef Name = MethodDeclNode->getName();
if (!MethodDeclNode->isConst() || MethodDeclNode->getNumParams() != 0 ||
(Name != "size" && Name != "length")) {
return true;
}

if (const auto *OnNode =
dyn_cast<Expr>(MemberCallNode->getImplicitObjectArgument())) {
return !utils::areStatementsIdentical(OnNode->IgnoreParenImpCasts(),
ExprNode->IgnoreParenImpCasts(),
*Context);
}
}
}

return true;
}

private:
std::string ID;
DynTypedNode Node;
ASTContext *Context;
};

AST_MATCHER_P(Expr, lengthExprForStringNode, std::string, ID) {
return Builder->removeBindings(NotLengthExprForStringNode(
ID, DynTypedNode::create(Node), &(Finder->getASTContext())));
}

UseStartsEndsWithCheck::UseStartsEndsWithCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context) {}

void UseStartsEndsWithCheck::registerMatchers(MatchFinder *Finder) {
const auto ZeroLiteral = integerLiteral(equals(0));

const auto HasStartsWithMethodWithName = [](const std::string &Name) {
return hasMethod(
cxxMethodDecl(hasName(Name), isConst(), parameterCountIs(1))
Expand All @@ -32,119 +91,104 @@ void UseStartsEndsWithCheck::registerMatchers(MatchFinder *Finder) {
anyOf(HasStartsWithMethodWithName("starts_with"),
HasStartsWithMethodWithName("startsWith"),
HasStartsWithMethodWithName("startswith"));
const auto ClassWithStartsWithFunction = cxxRecordDecl(anyOf(
HasStartsWithMethod, hasAnyBase(hasType(hasCanonicalType(hasDeclaration(
cxxRecordDecl(HasStartsWithMethod)))))));
const auto OnClassWithStartsWithFunction =
on(hasType(hasCanonicalType(hasDeclaration(cxxRecordDecl(
anyOf(HasStartsWithMethod,
hasAnyBase(hasType(hasCanonicalType(
hasDeclaration(cxxRecordDecl(HasStartsWithMethod)))))))))));

const auto HasEndsWithMethodWithName = [](const std::string &Name) {
return hasMethod(
cxxMethodDecl(hasName(Name), isConst(), parameterCountIs(1))
.bind("ends_with_fun"));
};
const auto HasEndsWithMethod = anyOf(HasEndsWithMethodWithName("ends_with"),
HasEndsWithMethodWithName("endsWith"),
HasEndsWithMethodWithName("endswith"));
const auto OnClassWithEndsWithFunction =
on(expr(hasType(hasCanonicalType(hasDeclaration(cxxRecordDecl(
anyOf(HasEndsWithMethod,
hasAnyBase(hasType(hasCanonicalType(hasDeclaration(
cxxRecordDecl(HasEndsWithMethod)))))))))))
.bind("haystack"));

// Case 1: X.find(Y) [!=]= 0 -> starts_with.
const auto FindExpr = cxxMemberCallExpr(
// A method call with no second argument or the second argument is zero...
anyOf(argumentCountIs(1), hasArgument(1, ZeroLiteral)),
// ... named find...
callee(cxxMethodDecl(hasName("find")).bind("find_fun")),
// ... on a class with a starts_with function.
on(hasType(
hasCanonicalType(hasDeclaration(ClassWithStartsWithFunction)))),
// Bind search expression.
hasArgument(0, expr().bind("search_expr")));
OnClassWithStartsWithFunction, hasArgument(0, expr().bind("needle")));

// Case 2: X.rfind(Y, 0) [!=]= 0 -> starts_with.
const auto RFindExpr = cxxMemberCallExpr(
// A method call with a second argument of zero...
hasArgument(1, ZeroLiteral),
// ... named rfind...
callee(cxxMethodDecl(hasName("rfind")).bind("find_fun")),
// ... on a class with a starts_with function.
on(hasType(
hasCanonicalType(hasDeclaration(ClassWithStartsWithFunction)))),
// Bind search expression.
hasArgument(0, expr().bind("search_expr")));

// Match a string literal and an integer or strlen() call matching the length.
const auto HasStringLiteralAndLengthArgs = [](const auto StringArgIndex,
const auto LengthArgIndex) {
return allOf(
hasArgument(StringArgIndex, stringLiteral().bind("string_literal_arg")),
hasArgument(LengthArgIndex,
anyOf(integerLiteral().bind("integer_literal_size_arg"),
callExpr(callee(functionDecl(parameterCountIs(1),
hasName("strlen"))),
hasArgument(0, stringLiteral().bind(
"strlen_arg"))))));
};

// Match a string variable and a call to length() or size().
const auto HasStringVariableAndSizeCallArgs = [](const auto StringArgIndex,
const auto LengthArgIndex) {
return allOf(
hasArgument(StringArgIndex, declRefExpr(hasDeclaration(
decl().bind("string_var_decl")))),
hasArgument(LengthArgIndex,
cxxMemberCallExpr(
callee(cxxMethodDecl(isConst(), parameterCountIs(0),
hasAnyName("size", "length"))),
on(declRefExpr(
to(decl(equalsBoundNode("string_var_decl"))))))));
};

// Match either one of the two cases above.
const auto HasStringAndLengthArgs =
[HasStringLiteralAndLengthArgs, HasStringVariableAndSizeCallArgs](
const auto StringArgIndex, const auto LengthArgIndex) {
return anyOf(
HasStringLiteralAndLengthArgs(StringArgIndex, LengthArgIndex),
HasStringVariableAndSizeCallArgs(StringArgIndex, LengthArgIndex));
};
OnClassWithStartsWithFunction, hasArgument(0, expr().bind("needle")));

// Case 3: X.compare(0, LEN(Y), Y) [!=]= 0 -> starts_with.
const auto CompareExpr = cxxMemberCallExpr(
// A method call with three arguments...
argumentCountIs(3),
// ... where the first argument is zero...
hasArgument(0, ZeroLiteral),
// ... named compare...
argumentCountIs(3), hasArgument(0, ZeroLiteral),
callee(cxxMethodDecl(hasName("compare")).bind("find_fun")),
// ... on a class with a starts_with function...
on(hasType(
hasCanonicalType(hasDeclaration(ClassWithStartsWithFunction)))),
// ... where the third argument is some string and the second a length.
HasStringAndLengthArgs(2, 1),
// Bind search expression.
hasArgument(2, expr().bind("search_expr")));
OnClassWithStartsWithFunction, hasArgument(2, expr().bind("needle")),
hasArgument(1, lengthExprForStringNode("needle")));

// Case 4: X.compare(LEN(X) - LEN(Y), LEN(Y), Y) [!=]= 0 -> ends_with.
const auto CompareEndsWithExpr = cxxMemberCallExpr(
argumentCountIs(3),
callee(cxxMethodDecl(hasName("compare")).bind("find_fun")),
OnClassWithEndsWithFunction, hasArgument(2, expr().bind("needle")),
hasArgument(1, lengthExprForStringNode("needle")),
hasArgument(0,
binaryOperator(hasOperatorName("-"),
hasLHS(lengthExprForStringNode("haystack")),
hasRHS(lengthExprForStringNode("needle")))));

// All cases comparing to 0.
Finder->addMatcher(
// Match [=!]= with a zero on one side and (r?)find|compare on the other.
binaryOperator(
hasAnyOperatorName("==", "!="),
hasOperands(cxxMemberCallExpr(anyOf(FindExpr, RFindExpr, CompareExpr))
hasOperands(cxxMemberCallExpr(anyOf(FindExpr, RFindExpr, CompareExpr,
CompareEndsWithExpr))
.bind("find_expr"),
ZeroLiteral))
.bind("expr"),
this);

// Case 5: X.rfind(Y) [!=]= LEN(X) - LEN(Y) -> ends_with.
Finder->addMatcher(
binaryOperator(
hasAnyOperatorName("==", "!="),
hasOperands(
cxxMemberCallExpr(
anyOf(
argumentCountIs(1),
allOf(argumentCountIs(2),
hasArgument(
1,
anyOf(declRefExpr(to(varDecl(hasName("npos")))),
memberExpr(member(hasName("npos"))))))),
callee(cxxMethodDecl(hasName("rfind")).bind("find_fun")),
OnClassWithEndsWithFunction,
hasArgument(0, expr().bind("needle")))
.bind("find_expr"),
binaryOperator(hasOperatorName("-"),
hasLHS(lengthExprForStringNode("haystack")),
hasRHS(lengthExprForStringNode("needle")))))
.bind("expr"),
this);
}

void UseStartsEndsWithCheck::check(const MatchFinder::MatchResult &Result) {
const auto *ComparisonExpr = Result.Nodes.getNodeAs<BinaryOperator>("expr");
const auto *FindExpr = Result.Nodes.getNodeAs<CXXMemberCallExpr>("find_expr");
const auto *FindFun = Result.Nodes.getNodeAs<CXXMethodDecl>("find_fun");
const auto *SearchExpr = Result.Nodes.getNodeAs<Expr>("search_expr");
const auto *SearchExpr = Result.Nodes.getNodeAs<Expr>("needle");
const auto *StartsWithFunction =
Result.Nodes.getNodeAs<CXXMethodDecl>("starts_with_fun");

const auto *StringLiteralArg =
Result.Nodes.getNodeAs<StringLiteral>("string_literal_arg");
const auto *IntegerLiteralSizeArg =
Result.Nodes.getNodeAs<IntegerLiteral>("integer_literal_size_arg");
const auto *StrlenArg = Result.Nodes.getNodeAs<StringLiteral>("strlen_arg");

// Filter out compare cases where the length does not match string literal.
if (StringLiteralArg && IntegerLiteralSizeArg &&
StringLiteralArg->getLength() !=
IntegerLiteralSizeArg->getValue().getZExtValue()) {
return;
}

if (StringLiteralArg && StrlenArg &&
StringLiteralArg->getLength() != StrlenArg->getLength()) {
return;
}
const auto *EndsWithFunction =
Result.Nodes.getNodeAs<CXXMethodDecl>("ends_with_fun");
assert(bool(StartsWithFunction) != bool(EndsWithFunction));
const CXXMethodDecl *ReplacementFunction =
StartsWithFunction ? StartsWithFunction : EndsWithFunction;

if (ComparisonExpr->getBeginLoc().isMacroID()) {
return;
Expand All @@ -154,26 +198,26 @@ void UseStartsEndsWithCheck::check(const MatchFinder::MatchResult &Result) {

auto Diagnostic =
diag(FindExpr->getExprLoc(), "use %0 instead of %1() %select{==|!=}2 0")
<< StartsWithFunction->getName() << FindFun->getName() << Neg;
<< ReplacementFunction->getName() << FindFun->getName() << Neg;

// Remove possible arguments after search expression and ' [!=]= 0' suffix.
// Remove possible arguments after search expression and ' [!=]= .+' suffix.
Diagnostic << FixItHint::CreateReplacement(
CharSourceRange::getTokenRange(
Lexer::getLocForEndOfToken(SearchExpr->getEndLoc(), 0,
*Result.SourceManager, getLangOpts()),
ComparisonExpr->getEndLoc()),
")");

// Remove possible '0 [!=]= ' prefix.
// Remove possible '.+ [!=]= ' prefix.
Diagnostic << FixItHint::CreateRemoval(CharSourceRange::getCharRange(
ComparisonExpr->getBeginLoc(), FindExpr->getBeginLoc()));

// Replace method name by 'starts_with'.
// Replace method name by '(starts|ends)_with'.
// Remove possible arguments before search expression.
Diagnostic << FixItHint::CreateReplacement(
CharSourceRange::getCharRange(FindExpr->getExprLoc(),
SearchExpr->getBeginLoc()),
(StartsWithFunction->getName() + "(").str());
(ReplacementFunction->getName() + "(").str());

// Add possible negation '!'.
if (Neg) {
Expand Down
2 changes: 1 addition & 1 deletion clang-tools-extra/clang-tidy/modernize/UseStartsEndsWithCheck.h
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Expand Up @@ -14,7 +14,7 @@
namespace clang::tidy::modernize {

/// Checks for common roundabout ways to express ``starts_with`` and
/// ``ends_with`` and suggests replacing with ``starts_with`` when the method is
/// ``ends_with`` and suggests replacing with the simpler method when it is
/// available. Notably, this will work with ``std::string`` and
/// ``std::string_view``.
///
Expand Down
4 changes: 4 additions & 0 deletions clang-tools-extra/docs/ReleaseNotes.rst
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Expand Up @@ -108,6 +108,10 @@ Changes in existing checks
<clang-tidy/checks/bugprone/casting-through-void>` check to suggest replacing
the offending code with ``reinterpret_cast``, to more clearly express intent.

- Improved :doc:`modernize-use-starts-ends-with
<clang-tidy/checks/modernize/use-starts-ends-with>` check to handle two cases
that can be replaced with ``ends_with``.

- Improved :doc:`modernize-use-std-format
<clang-tidy/checks/modernize/use-std-format>` check to support replacing
member function calls too.
Expand Down
12 changes: 10 additions & 2 deletions clang-tools-extra/docs/clang-tidy/checks/modernize/use-starts-ends-with.rst
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Expand Up @@ -4,15 +4,21 @@ modernize-use-starts-ends-with
==============================

Checks for common roundabout ways to express ``starts_with`` and ``ends_with``
and suggests replacing with ``starts_with`` when the method is available.
Notably, this will work with ``std::string`` and ``std::string_view``.
and suggests replacing with the simpler method when it is available. Notably,
this will work with ``std::string`` and ``std::string_view``.

.. code-block:: c++

std::string s = "...";
if (s.find("prefix") == 0) { /* do something */ }
if (s.rfind("prefix", 0) == 0) { /* do something */ }
if (s.compare(0, strlen("prefix"), "prefix") == 0) { /* do something */ }
if (s.compare(s.size() - strlen("suffix"), strlen("suffix"), "suffix") == 0) {
/* do something */
}
if (s.rfind("suffix") == (s.length() - 6)) {
/* do something */
}
becomes

Expand All @@ -22,3 +28,5 @@ becomes
if (s.starts_with("prefix")) { /* do something */ }
if (s.starts_with("prefix")) { /* do something */ }
if (s.starts_with("prefix")) { /* do something */ }
if (s.ends_with("suffix")) { /* do something */ }
if (s.ends_with("suffix")) { /* do something */ }
8 changes: 8 additions & 0 deletions clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/string
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Expand Up @@ -64,6 +64,10 @@ struct basic_string {
constexpr bool starts_with(C ch) const noexcept;
constexpr bool starts_with(const C* s) const;

constexpr bool ends_with(std::basic_string_view<C, T> sv) const noexcept;
constexpr bool ends_with(C ch) const noexcept;
constexpr bool ends_with(const C* s) const;

_Type& operator[](size_type);
const _Type& operator[](size_type) const;

Expand Down Expand Up @@ -108,6 +112,10 @@ struct basic_string_view {
constexpr bool starts_with(C ch) const noexcept;
constexpr bool starts_with(const C* s) const;

constexpr bool ends_with(basic_string_view sv) const noexcept;
constexpr bool ends_with(C ch) const noexcept;
constexpr bool ends_with(const C* s) const;

constexpr int compare(basic_string_view sv) const noexcept;

static constexpr size_t npos = -1;
Expand Down
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