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//===--- StringviewNullptrCheck.cpp - clang-tidy --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "StringviewNullptrCheck.h"
#include "../utils/TransformerClangTidyCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/OperationKinds.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Tooling/Transformer/RangeSelector.h"
#include "clang/Tooling/Transformer/RewriteRule.h"
#include "clang/Tooling/Transformer/Stencil.h"
#include "llvm/ADT/StringRef.h"
namespace clang::tidy::bugprone {
using namespace ::clang::ast_matchers;
using namespace ::clang::transformer;
namespace {
AST_MATCHER_P(InitListExpr, initCountIs, unsigned, N) {
return Node.getNumInits() == N;
}
AST_MATCHER(clang::VarDecl, isDirectInitialization) {
return Node.getInitStyle() != clang::VarDecl::InitializationStyle::CInit;
}
} // namespace
RewriteRuleWith<std::string> StringviewNullptrCheckImpl() {
auto construction_warning =
cat("constructing basic_string_view from null is undefined; replace with "
"the default constructor");
auto static_cast_warning =
cat("casting to basic_string_view from null is undefined; replace with "
"the empty string");
auto argument_construction_warning =
cat("passing null as basic_string_view is undefined; replace with the "
"empty string");
auto assignment_warning =
cat("assignment to basic_string_view from null is undefined; replace "
"with the default constructor");
auto relative_comparison_warning =
cat("comparing basic_string_view to null is undefined; replace with the "
"empty string");
auto equality_comparison_warning =
cat("comparing basic_string_view to null is undefined; replace with the "
"emptiness query");
// Matches declarations and expressions of type `basic_string_view`
auto HasBasicStringViewType = hasType(hasUnqualifiedDesugaredType(recordType(
hasDeclaration(cxxRecordDecl(hasName("::std::basic_string_view"))))));
// Matches `nullptr` and `(nullptr)` binding to a pointer
auto NullLiteral = implicitCastExpr(
hasCastKind(clang::CK_NullToPointer),
hasSourceExpression(ignoringParens(cxxNullPtrLiteralExpr())));
// Matches `{nullptr}` and `{(nullptr)}` binding to a pointer
auto NullInitList = initListExpr(initCountIs(1), hasInit(0, NullLiteral));
// Matches `{}`
auto EmptyInitList = initListExpr(initCountIs(0));
// Matches null construction without `basic_string_view` type spelling
auto BasicStringViewConstructingFromNullExpr =
cxxConstructExpr(
HasBasicStringViewType, argumentCountIs(1),
hasAnyArgument(/* `hasArgument` would skip over parens */ anyOf(
NullLiteral, NullInitList, EmptyInitList)),
unless(cxxTemporaryObjectExpr(/* filters out type spellings */)),
has(expr().bind("null_arg_expr")))
.bind("construct_expr");
// `std::string_view(null_arg_expr)`
auto HandleTemporaryCXXFunctionalCastExpr =
makeRule(cxxFunctionalCastExpr(hasSourceExpression(
BasicStringViewConstructingFromNullExpr)),
remove(node("null_arg_expr")), construction_warning);
// `std::string_view{null_arg_expr}` and `(std::string_view){null_arg_expr}`
auto HandleTemporaryCXXTemporaryObjectExprAndCompoundLiteralExpr = makeRule(
cxxTemporaryObjectExpr(cxxConstructExpr(
HasBasicStringViewType, argumentCountIs(1),
hasAnyArgument(/* `hasArgument` would skip over parens */ anyOf(
NullLiteral, NullInitList, EmptyInitList)),
has(expr().bind("null_arg_expr")))),
remove(node("null_arg_expr")), construction_warning);
// `(std::string_view) null_arg_expr`
auto HandleTemporaryCStyleCastExpr = makeRule(
cStyleCastExpr(
hasSourceExpression(BasicStringViewConstructingFromNullExpr)),
changeTo(node("null_arg_expr"), cat("{}")), construction_warning);
// `static_cast<std::string_view>(null_arg_expr)`
auto HandleTemporaryCXXStaticCastExpr = makeRule(
cxxStaticCastExpr(
hasSourceExpression(BasicStringViewConstructingFromNullExpr)),
changeTo(node("null_arg_expr"), cat("\"\"")), static_cast_warning);
// `std::string_view sv = null_arg_expr;`
auto HandleStackCopyInitialization = makeRule(
varDecl(HasBasicStringViewType,
hasInitializer(ignoringImpCasts(
cxxConstructExpr(BasicStringViewConstructingFromNullExpr,
unless(isListInitialization())))),
unless(isDirectInitialization())),
changeTo(node("null_arg_expr"), cat("{}")), construction_warning);
// `std::string_view sv = {null_arg_expr};`
auto HandleStackCopyListInitialization =
makeRule(varDecl(HasBasicStringViewType,
hasInitializer(cxxConstructExpr(
BasicStringViewConstructingFromNullExpr,
isListInitialization())),
unless(isDirectInitialization())),
remove(node("null_arg_expr")), construction_warning);
// `std::string_view sv(null_arg_expr);`
auto HandleStackDirectInitialization =
makeRule(varDecl(HasBasicStringViewType,
hasInitializer(cxxConstructExpr(
BasicStringViewConstructingFromNullExpr,
unless(isListInitialization()))),
isDirectInitialization())
.bind("var_decl"),
changeTo(node("construct_expr"), cat(name("var_decl"))),
construction_warning);
// `std::string_view sv{null_arg_expr};`
auto HandleStackDirectListInitialization =
makeRule(varDecl(HasBasicStringViewType,
hasInitializer(cxxConstructExpr(
BasicStringViewConstructingFromNullExpr,
isListInitialization())),
isDirectInitialization()),
remove(node("null_arg_expr")), construction_warning);
// `struct S { std::string_view sv = null_arg_expr; };`
auto HandleFieldInClassCopyInitialization = makeRule(
fieldDecl(HasBasicStringViewType,
hasInClassInitializer(ignoringImpCasts(
cxxConstructExpr(BasicStringViewConstructingFromNullExpr,
unless(isListInitialization()))))),
changeTo(node("null_arg_expr"), cat("{}")), construction_warning);
// `struct S { std::string_view sv = {null_arg_expr}; };` and
// `struct S { std::string_view sv{null_arg_expr}; };`
auto HandleFieldInClassCopyListAndDirectListInitialization = makeRule(
fieldDecl(HasBasicStringViewType,
hasInClassInitializer(ignoringImpCasts(
cxxConstructExpr(BasicStringViewConstructingFromNullExpr,
isListInitialization())))),
remove(node("null_arg_expr")), construction_warning);
// `class C { std::string_view sv; C() : sv(null_arg_expr) {} };`
auto HandleConstructorDirectInitialization =
makeRule(cxxCtorInitializer(forField(fieldDecl(HasBasicStringViewType)),
withInitializer(cxxConstructExpr(
BasicStringViewConstructingFromNullExpr,
unless(isListInitialization())))),
remove(node("null_arg_expr")), construction_warning);
// `class C { std::string_view sv; C() : sv{null_arg_expr} {} };`
auto HandleConstructorDirectListInitialization =
makeRule(cxxCtorInitializer(forField(fieldDecl(HasBasicStringViewType)),
withInitializer(cxxConstructExpr(
BasicStringViewConstructingFromNullExpr,
isListInitialization()))),
remove(node("null_arg_expr")), construction_warning);
// `void f(std::string_view sv = null_arg_expr);`
auto HandleDefaultArgumentCopyInitialization = makeRule(
parmVarDecl(HasBasicStringViewType,
hasInitializer(ignoringImpCasts(
cxxConstructExpr(BasicStringViewConstructingFromNullExpr,
unless(isListInitialization()))))),
changeTo(node("null_arg_expr"), cat("{}")), construction_warning);
// `void f(std::string_view sv = {null_arg_expr});`
auto HandleDefaultArgumentCopyListInitialization =
makeRule(parmVarDecl(HasBasicStringViewType,
hasInitializer(cxxConstructExpr(
BasicStringViewConstructingFromNullExpr,
isListInitialization()))),
remove(node("null_arg_expr")), construction_warning);
// `new std::string_view(null_arg_expr)`
auto HandleHeapDirectInitialization = makeRule(
cxxNewExpr(has(cxxConstructExpr(BasicStringViewConstructingFromNullExpr,
unless(isListInitialization()))),
unless(isArray()), unless(hasAnyPlacementArg(anything()))),
remove(node("null_arg_expr")), construction_warning);
// `new std::string_view{null_arg_expr}`
auto HandleHeapDirectListInitialization = makeRule(
cxxNewExpr(has(cxxConstructExpr(BasicStringViewConstructingFromNullExpr,
isListInitialization())),
unless(isArray()), unless(hasAnyPlacementArg(anything()))),
remove(node("null_arg_expr")), construction_warning);
// `function(null_arg_expr)`
auto HandleFunctionArgumentInitialization =
makeRule(callExpr(hasAnyArgument(ignoringImpCasts(
BasicStringViewConstructingFromNullExpr)),
unless(cxxOperatorCallExpr())),
changeTo(node("construct_expr"), cat("\"\"")),
argument_construction_warning);
// `sv = null_arg_expr`
auto HandleAssignment = makeRule(
cxxOperatorCallExpr(hasOverloadedOperatorName("="),
hasRHS(materializeTemporaryExpr(
has(BasicStringViewConstructingFromNullExpr)))),
changeTo(node("construct_expr"), cat("{}")), assignment_warning);
// `sv < null_arg_expr`
auto HandleRelativeComparison = makeRule(
cxxOperatorCallExpr(hasAnyOverloadedOperatorName("<", "<=", ">", ">="),
hasEitherOperand(ignoringImpCasts(
BasicStringViewConstructingFromNullExpr))),
changeTo(node("construct_expr"), cat("\"\"")),
relative_comparison_warning);
// `sv == null_arg_expr`
auto HandleEmptyEqualityComparison = makeRule(
cxxOperatorCallExpr(
hasOverloadedOperatorName("=="),
hasOperands(ignoringImpCasts(BasicStringViewConstructingFromNullExpr),
traverse(clang::TK_IgnoreUnlessSpelledInSource,
expr().bind("instance"))))
.bind("root"),
changeTo(node("root"), cat(access("instance", cat("empty")), "()")),
equality_comparison_warning);
// `sv != null_arg_expr`
auto HandleNonEmptyEqualityComparison = makeRule(
cxxOperatorCallExpr(
hasOverloadedOperatorName("!="),
hasOperands(ignoringImpCasts(BasicStringViewConstructingFromNullExpr),
traverse(clang::TK_IgnoreUnlessSpelledInSource,
expr().bind("instance"))))
.bind("root"),
changeTo(node("root"), cat("!", access("instance", cat("empty")), "()")),
equality_comparison_warning);
// `return null_arg_expr;`
auto HandleReturnStatement = makeRule(
returnStmt(hasReturnValue(
ignoringImpCasts(BasicStringViewConstructingFromNullExpr))),
changeTo(node("construct_expr"), cat("{}")), construction_warning);
// `T(null_arg_expr)`
auto HandleConstructorInvocation =
makeRule(cxxConstructExpr(
hasAnyArgument(/* `hasArgument` would skip over parens */
ignoringImpCasts(
BasicStringViewConstructingFromNullExpr)),
unless(HasBasicStringViewType)),
changeTo(node("construct_expr"), cat("\"\"")),
argument_construction_warning);
return applyFirst(
{HandleTemporaryCXXFunctionalCastExpr,
HandleTemporaryCXXTemporaryObjectExprAndCompoundLiteralExpr,
HandleTemporaryCStyleCastExpr,
HandleTemporaryCXXStaticCastExpr,
HandleStackCopyInitialization,
HandleStackCopyListInitialization,
HandleStackDirectInitialization,
HandleStackDirectListInitialization,
HandleFieldInClassCopyInitialization,
HandleFieldInClassCopyListAndDirectListInitialization,
HandleConstructorDirectInitialization,
HandleConstructorDirectListInitialization,
HandleDefaultArgumentCopyInitialization,
HandleDefaultArgumentCopyListInitialization,
HandleHeapDirectInitialization,
HandleHeapDirectListInitialization,
HandleFunctionArgumentInitialization,
HandleAssignment,
HandleRelativeComparison,
HandleEmptyEqualityComparison,
HandleNonEmptyEqualityComparison,
HandleReturnStatement,
HandleConstructorInvocation});
}
StringviewNullptrCheck::StringviewNullptrCheck(StringRef Name,
ClangTidyContext *Context)
: utils::TransformerClangTidyCheck(StringviewNullptrCheckImpl(), Name,
Context) {}
} // namespace clang::tidy::bugprone
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