1//===--- LoopConvertCheck.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 "LoopConvertCheck.h"
10#include "clang/AST/ASTContext.h"
11#include "clang/ASTMatchers/ASTMatchFinder.h"
12#include "clang/Basic/LLVM.h"
13#include "clang/Basic/LangOptions.h"
14#include "clang/Basic/SourceLocation.h"
15#include "clang/Basic/SourceManager.h"
16#include "clang/Lex/Lexer.h"
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/ADT/StringRef.h"
20#include "llvm/ADT/StringSet.h"
21#include "llvm/Support/raw_ostream.h"
22#include <cassert>
23#include <cstring>
24#include <optional>
25#include <utility>
26
27using namespace clang::ast_matchers;
28using namespace llvm;
29
30namespace clang::tidy {
31
32template <> struct OptionEnumMapping<modernize::Confidence::Level> {
33 static llvm::ArrayRef<std::pair<modernize::Confidence::Level, StringRef>>
34 getEnumMapping() {
35 static constexpr std::pair<modernize::Confidence::Level, StringRef>
36 Mapping[] = {{modernize::Confidence::CL_Reasonable, "reasonable"},
37 {modernize::Confidence::CL_Safe, "safe"},
38 {modernize::Confidence::CL_Risky, "risky"}};
39 return {Mapping};
40 }
41};
42
43template <> struct OptionEnumMapping<modernize::VariableNamer::NamingStyle> {
44 static llvm::ArrayRef<
45 std::pair<modernize::VariableNamer::NamingStyle, StringRef>>
46 getEnumMapping() {
47 static constexpr std::pair<modernize::VariableNamer::NamingStyle, StringRef>
48 Mapping[] = {{modernize::VariableNamer::NS_CamelCase, "CamelCase"},
49 {modernize::VariableNamer::NS_CamelBack, "camelBack"},
50 {modernize::VariableNamer::NS_LowerCase, "lower_case"},
51 {modernize::VariableNamer::NS_UpperCase, "UPPER_CASE"}};
52 return {Mapping};
53 }
54};
55
56namespace modernize {
57
58static const char LoopNameArray[] = "forLoopArray";
59static const char LoopNameIterator[] = "forLoopIterator";
60static const char LoopNameReverseIterator[] = "forLoopReverseIterator";
61static const char LoopNamePseudoArray[] = "forLoopPseudoArray";
62static const char ConditionBoundName[] = "conditionBound";
63static const char InitVarName[] = "initVar";
64static const char BeginCallName[] = "beginCall";
65static const char EndCallName[] = "endCall";
66static const char EndVarName[] = "endVar";
67static const char DerefByValueResultName[] = "derefByValueResult";
68static const char DerefByRefResultName[] = "derefByRefResult";
69static const llvm::StringSet<> MemberNames{"begin", "cbegin", "rbegin",
70 "crbegin", "end", "cend",
71 "rend", "crend", "size"};
72static const llvm::StringSet<> ADLNames{"begin", "cbegin", "rbegin",
73 "crbegin", "end", "cend",
74 "rend", "crend", "size"};
75static const llvm::StringSet<> StdNames{
76 "std::begin", "std::cbegin", "std::rbegin", "std::crbegin", "std::end",
77 "std::cend", "std::rend", "std::crend", "std::size"};
78
79static StatementMatcher integerComparisonMatcher() {
80 return expr(ignoringParenImpCasts(
81 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName))))));
82}
83
84static DeclarationMatcher initToZeroMatcher() {
85 return varDecl(
86 hasInitializer(InnerMatcher: ignoringParenImpCasts(InnerMatcher: integerLiteral(equals(Value: 0)))))
87 .bind(ID: InitVarName);
88}
89
90static StatementMatcher incrementVarMatcher() {
91 return declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName))));
92}
93
94static StatementMatcher
95arrayConditionMatcher(internal::Matcher<Expr> LimitExpr) {
96 return binaryOperator(
97 anyOf(allOf(hasOperatorName(Name: "<"), hasLHS(InnerMatcher: integerComparisonMatcher()),
98 hasRHS(InnerMatcher: LimitExpr)),
99 allOf(hasOperatorName(Name: ">"), hasLHS(InnerMatcher: LimitExpr),
100 hasRHS(InnerMatcher: integerComparisonMatcher())),
101 allOf(hasOperatorName(Name: "!="),
102 hasOperands(Matcher1: integerComparisonMatcher(), Matcher2: LimitExpr))));
103}
104
105/// The matcher for loops over arrays.
106/// \code
107/// for (int i = 0; i < 3 + 2; ++i) { ... }
108/// \endcode
109/// The following string identifiers are bound to these parts of the AST:
110/// ConditionBoundName: '3 + 2' (as an Expr)
111/// InitVarName: 'i' (as a VarDecl)
112/// LoopName: The entire for loop (as a ForStmt)
113///
114/// Client code will need to make sure that:
115/// - The index variable is only used as an array index.
116/// - All arrays indexed by the loop are the same.
117static StatementMatcher makeArrayLoopMatcher() {
118 StatementMatcher ArrayBoundMatcher =
119 expr(hasType(InnerMatcher: isInteger())).bind(ID: ConditionBoundName);
120
121 return forStmt(unless(isInTemplateInstantiation()),
122 hasLoopInit(InnerMatcher: declStmt(hasSingleDecl(InnerMatcher: initToZeroMatcher()))),
123 hasCondition(InnerMatcher: arrayConditionMatcher(LimitExpr: ArrayBoundMatcher)),
124 hasIncrement(
125 InnerMatcher: unaryOperator(hasOperatorName(Name: "++"),
126 hasUnaryOperand(InnerMatcher: incrementVarMatcher()))))
127 .bind(ID: LoopNameArray);
128}
129
130/// The matcher used for iterator-based for loops.
131///
132/// This matcher is more flexible than array-based loops. It will match
133/// catch loops of the following textual forms (regardless of whether the
134/// iterator type is actually a pointer type or a class type):
135///
136/// \code
137/// for (containerType::iterator it = container.begin(),
138/// e = createIterator(); it != e; ++it) { ... }
139/// for (containerType::iterator it = container.begin();
140/// it != anotherContainer.end(); ++it) { ... }
141/// for (containerType::iterator it = begin(container),
142/// e = end(container); it != e; ++it) { ... }
143/// for (containerType::iterator it = std::begin(container),
144/// e = std::end(container); it != e; ++it) { ... }
145/// \endcode
146/// The following string identifiers are bound to the parts of the AST:
147/// InitVarName: 'it' (as a VarDecl)
148/// LoopName: The entire for loop (as a ForStmt)
149/// In the first example only:
150/// EndVarName: 'e' (as a VarDecl)
151/// In the second example only:
152/// EndCallName: 'container.end()' (as a CXXMemberCallExpr)
153/// In the third/fourth examples:
154/// 'end(container)' or 'std::end(container)' (as a CallExpr)
155///
156/// Client code will need to make sure that:
157/// - The two containers on which 'begin' and 'end' are called are the same.
158static StatementMatcher makeIteratorLoopMatcher(bool IsReverse) {
159
160 auto BeginNameMatcher = IsReverse ? hasAnyName("rbegin", "crbegin")
161 : hasAnyName("begin", "cbegin");
162 auto BeginNameMatcherStd = IsReverse
163 ? hasAnyName("::std::rbegin", "::std::crbegin")
164 : hasAnyName("::std::begin", "::std::cbegin");
165
166 auto EndNameMatcher =
167 IsReverse ? hasAnyName("rend", "crend") : hasAnyName("end", "cend");
168 auto EndNameMatcherStd = IsReverse ? hasAnyName("::std::rend", "::std::crend")
169 : hasAnyName("::std::end", "::std::cend");
170
171 StatementMatcher BeginCallMatcher =
172 expr(anyOf(cxxMemberCallExpr(argumentCountIs(N: 0),
173 callee(InnerMatcher: cxxMethodDecl(BeginNameMatcher))),
174 callExpr(argumentCountIs(N: 1),
175 callee(InnerMatcher: functionDecl(BeginNameMatcher)), usesADL()),
176 callExpr(argumentCountIs(N: 1),
177 callee(InnerMatcher: functionDecl(BeginNameMatcherStd)))))
178 .bind(ID: BeginCallName);
179
180 DeclarationMatcher InitDeclMatcher =
181 varDecl(hasInitializer(InnerMatcher: anyOf(ignoringParenImpCasts(InnerMatcher: BeginCallMatcher),
182 materializeTemporaryExpr(
183 ignoringParenImpCasts(InnerMatcher: BeginCallMatcher)),
184 hasDescendant(BeginCallMatcher))))
185 .bind(ID: InitVarName);
186
187 DeclarationMatcher EndDeclMatcher =
188 varDecl(hasInitializer(InnerMatcher: anything())).bind(ID: EndVarName);
189
190 StatementMatcher EndCallMatcher = expr(anyOf(
191 cxxMemberCallExpr(argumentCountIs(N: 0),
192 callee(InnerMatcher: cxxMethodDecl(EndNameMatcher))),
193 callExpr(argumentCountIs(N: 1), callee(InnerMatcher: functionDecl(EndNameMatcher)),
194 usesADL()),
195 callExpr(argumentCountIs(N: 1), callee(InnerMatcher: functionDecl(EndNameMatcherStd)))));
196
197 StatementMatcher IteratorBoundMatcher =
198 expr(anyOf(ignoringParenImpCasts(
199 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: EndVarName))))),
200 ignoringParenImpCasts(InnerMatcher: expr(EndCallMatcher).bind(ID: EndCallName)),
201 materializeTemporaryExpr(ignoringParenImpCasts(
202 InnerMatcher: expr(EndCallMatcher).bind(ID: EndCallName)))));
203
204 StatementMatcher IteratorComparisonMatcher = expr(ignoringParenImpCasts(
205 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName))))));
206
207 // This matcher tests that a declaration is a CXXRecordDecl that has an
208 // overloaded operator*(). If the operator*() returns by value instead of by
209 // reference then the return type is tagged with DerefByValueResultName.
210 internal::Matcher<VarDecl> TestDerefReturnsByValue =
211 hasType(InnerMatcher: hasUnqualifiedDesugaredType(
212 InnerMatcher: recordType(hasDeclaration(InnerMatcher: cxxRecordDecl(hasMethod(InnerMatcher: cxxMethodDecl(
213 hasOverloadedOperatorName(Name: "*"),
214 anyOf(
215 // Tag the return type if it's by value.
216 returns(InnerMatcher: qualType(unless(hasCanonicalType(InnerMatcher: referenceType())))
217 .bind(ID: DerefByValueResultName)),
218 returns(
219 // Skip loops where the iterator's operator* returns an
220 // rvalue reference. This is just weird.
221 InnerMatcher: qualType(unless(hasCanonicalType(InnerMatcher: rValueReferenceType())))
222 .bind(ID: DerefByRefResultName))))))))));
223
224 return forStmt(
225 unless(isInTemplateInstantiation()),
226 hasLoopInit(InnerMatcher: anyOf(declStmt(declCountIs(N: 2),
227 containsDeclaration(N: 0, InnerMatcher: InitDeclMatcher),
228 containsDeclaration(N: 1, InnerMatcher: EndDeclMatcher)),
229 declStmt(hasSingleDecl(InnerMatcher: InitDeclMatcher)))),
230 hasCondition(InnerMatcher: ignoringImplicit(InnerMatcher: binaryOperation(
231 hasOperatorName(Name: "!="), hasOperands(Matcher1: IteratorComparisonMatcher,
232 Matcher2: IteratorBoundMatcher)))),
233 hasIncrement(InnerMatcher: anyOf(
234 unaryOperator(hasOperatorName(Name: "++"),
235 hasUnaryOperand(InnerMatcher: declRefExpr(
236 to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName)))))),
237 cxxOperatorCallExpr(
238 hasOverloadedOperatorName(Name: "++"),
239 hasArgument(N: 0, InnerMatcher: declRefExpr(to(
240 InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName),
241 TestDerefReturnsByValue))))))))
242 .bind(ID: IsReverse ? LoopNameReverseIterator : LoopNameIterator);
243}
244
245/// The matcher used for array-like containers (pseudoarrays).
246///
247/// This matcher is more flexible than array-based loops. It will match
248/// loops of the following textual forms (regardless of whether the
249/// iterator type is actually a pointer type or a class type):
250///
251/// \code
252/// for (int i = 0, j = container.size(); i < j; ++i) { ... }
253/// for (int i = 0; i < container.size(); ++i) { ... }
254/// for (int i = 0; i < size(container); ++i) { ... }
255/// \endcode
256/// The following string identifiers are bound to the parts of the AST:
257/// InitVarName: 'i' (as a VarDecl)
258/// LoopName: The entire for loop (as a ForStmt)
259/// In the first example only:
260/// EndVarName: 'j' (as a VarDecl)
261/// In the second example only:
262/// EndCallName: 'container.size()' (as a CXXMemberCallExpr) or
263/// 'size(container)' (as a CallExpr)
264///
265/// Client code will need to make sure that:
266/// - The containers on which 'size()' is called is the container indexed.
267/// - The index variable is only used in overloaded operator[] or
268/// container.at().
269/// - The container's iterators would not be invalidated during the loop.
270static StatementMatcher makePseudoArrayLoopMatcher() {
271 // Test that the incoming type has a record declaration that has methods
272 // called 'begin' and 'end'. If the incoming type is const, then make sure
273 // these methods are also marked const.
274 //
275 // FIXME: To be completely thorough this matcher should also ensure the
276 // return type of begin/end is an iterator that dereferences to the same as
277 // what operator[] or at() returns. Such a test isn't likely to fail except
278 // for pathological cases.
279 //
280 // FIXME: Also, a record doesn't necessarily need begin() and end(). Free
281 // functions called begin() and end() taking the container as an argument
282 // are also allowed.
283 TypeMatcher RecordWithBeginEnd = qualType(anyOf(
284 qualType(isConstQualified(),
285 hasUnqualifiedDesugaredType(InnerMatcher: recordType(hasDeclaration(
286 InnerMatcher: cxxRecordDecl(isSameOrDerivedFrom(Base: cxxRecordDecl(
287 hasMethod(InnerMatcher: cxxMethodDecl(hasName(Name: "begin"), isConst())),
288 hasMethod(InnerMatcher: cxxMethodDecl(hasName(Name: "end"),
289 isConst())))))) // hasDeclaration
290 ))), // qualType
291 qualType(unless(isConstQualified()),
292 hasUnqualifiedDesugaredType(InnerMatcher: recordType(hasDeclaration(
293 InnerMatcher: cxxRecordDecl(isSameOrDerivedFrom(Base: cxxRecordDecl(
294 hasMethod(InnerMatcher: hasName(Name: "begin")),
295 hasMethod(InnerMatcher: hasName(Name: "end"))))))))) // qualType
296 ));
297
298 StatementMatcher SizeCallMatcher = expr(anyOf(
299 cxxMemberCallExpr(argumentCountIs(N: 0),
300 callee(InnerMatcher: cxxMethodDecl(hasAnyName("size", "length"))),
301 on(InnerMatcher: anyOf(hasType(InnerMatcher: pointsTo(InnerMatcher: RecordWithBeginEnd)),
302 hasType(InnerMatcher: RecordWithBeginEnd)))),
303 callExpr(argumentCountIs(N: 1), callee(InnerMatcher: functionDecl(hasName(Name: "size"))),
304 usesADL()),
305 callExpr(argumentCountIs(N: 1),
306 callee(InnerMatcher: functionDecl(hasName(Name: "::std::size"))))));
307
308 StatementMatcher EndInitMatcher =
309 expr(anyOf(ignoringParenImpCasts(InnerMatcher: expr(SizeCallMatcher).bind(ID: EndCallName)),
310 explicitCastExpr(hasSourceExpression(InnerMatcher: ignoringParenImpCasts(
311 InnerMatcher: expr(SizeCallMatcher).bind(ID: EndCallName))))));
312
313 DeclarationMatcher EndDeclMatcher =
314 varDecl(hasInitializer(InnerMatcher: EndInitMatcher)).bind(ID: EndVarName);
315
316 StatementMatcher IndexBoundMatcher =
317 expr(anyOf(ignoringParenImpCasts(
318 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: EndVarName))))),
319 EndInitMatcher));
320
321 return forStmt(unless(isInTemplateInstantiation()),
322 hasLoopInit(
323 InnerMatcher: anyOf(declStmt(declCountIs(N: 2),
324 containsDeclaration(N: 0, InnerMatcher: initToZeroMatcher()),
325 containsDeclaration(N: 1, InnerMatcher: EndDeclMatcher)),
326 declStmt(hasSingleDecl(InnerMatcher: initToZeroMatcher())))),
327 hasCondition(InnerMatcher: arrayConditionMatcher(LimitExpr: IndexBoundMatcher)),
328 hasIncrement(
329 InnerMatcher: unaryOperator(hasOperatorName(Name: "++"),
330 hasUnaryOperand(InnerMatcher: incrementVarMatcher()))))
331 .bind(ID: LoopNamePseudoArray);
332}
333
334enum class IteratorCallKind {
335 ICK_Member,
336 ICK_ADL,
337 ICK_Std,
338};
339
340struct ContainerCall {
341 const Expr *Container;
342 StringRef Name;
343 bool IsArrow;
344 IteratorCallKind CallKind;
345};
346
347// Find the Expr likely initializing an iterator.
348//
349// Call is either a CXXMemberCallExpr ('c.begin()') or CallExpr of a free
350// function with the first argument as a container ('begin(c)'), or nullptr.
351// Returns at a 3-tuple with the container expr, function name (begin/end/etc),
352// and whether the call is made through an arrow (->) for CXXMemberCallExprs.
353// The returned Expr* is nullptr if any of the assumptions are not met.
354// static std::tuple<const Expr *, StringRef, bool, IteratorCallKind>
355static std::optional<ContainerCall> getContainerExpr(const Expr *Call) {
356 const Expr *Dug = digThroughConstructorsConversions(E: Call);
357
358 IteratorCallKind CallKind = IteratorCallKind::ICK_Member;
359
360 if (const auto *TheCall = dyn_cast_or_null<CXXMemberCallExpr>(Val: Dug)) {
361 CallKind = IteratorCallKind::ICK_Member;
362 if (const auto *Member = dyn_cast<MemberExpr>(TheCall->getCallee())) {
363 if (Member->getMemberDecl() == nullptr ||
364 !MemberNames.contains(key: Member->getMemberDecl()->getName()))
365 return std::nullopt;
366 return ContainerCall{TheCall->getImplicitObjectArgument(),
367 Member->getMemberDecl()->getName(),
368 Member->isArrow(), CallKind};
369 }
370 if (TheCall->getDirectCallee() == nullptr ||
371 !MemberNames.contains(key: TheCall->getDirectCallee()->getName()))
372 return std::nullopt;
373 return ContainerCall{TheCall->getArg(0),
374 TheCall->getDirectCallee()->getName(), false,
375 CallKind};
376 }
377 if (const auto *TheCall = dyn_cast_or_null<CallExpr>(Val: Dug)) {
378 if (TheCall->getNumArgs() != 1)
379 return std::nullopt;
380
381 if (TheCall->usesADL()) {
382 if (TheCall->getDirectCallee() == nullptr ||
383 !ADLNames.contains(key: TheCall->getDirectCallee()->getName()))
384 return std::nullopt;
385 CallKind = IteratorCallKind::ICK_ADL;
386 } else {
387 if (!StdNames.contains(
388 key: TheCall->getDirectCallee()->getQualifiedNameAsString()))
389 return std::nullopt;
390 CallKind = IteratorCallKind::ICK_Std;
391 }
392
393 if (TheCall->getDirectCallee() == nullptr)
394 return std::nullopt;
395
396 return ContainerCall{TheCall->getArg(Arg: 0),
397 TheCall->getDirectCallee()->getName(), false,
398 CallKind};
399 }
400 return std::nullopt;
401}
402
403/// Determine whether Init appears to be an initializing an iterator.
404///
405/// If it is, returns the object whose begin() or end() method is called, and
406/// the output parameter isArrow is set to indicate whether the initialization
407/// is called via . or ->.
408static std::pair<const Expr *, IteratorCallKind>
409getContainerFromBeginEndCall(const Expr *Init, bool IsBegin, bool *IsArrow,
410 bool IsReverse) {
411 // FIXME: Maybe allow declaration/initialization outside of the for loop.
412
413 std::optional<ContainerCall> Call = getContainerExpr(Call: Init);
414 if (!Call)
415 return {};
416
417 *IsArrow = Call->IsArrow;
418 if (!Call->Name.consume_back(Suffix: IsBegin ? "begin" : "end"))
419 return {};
420 if (IsReverse && !Call->Name.consume_back(Suffix: "r"))
421 return {};
422 if (!Call->Name.empty() && Call->Name != "c")
423 return {};
424 return std::make_pair(x&: Call->Container, y&: Call->CallKind);
425}
426
427/// Determines the container whose begin() and end() functions are called
428/// for an iterator-based loop.
429///
430/// BeginExpr must be a member call to a function named "begin()", and EndExpr
431/// must be a member.
432static const Expr *findContainer(ASTContext *Context, const Expr *BeginExpr,
433 const Expr *EndExpr,
434 bool *ContainerNeedsDereference,
435 bool IsReverse) {
436 // Now that we know the loop variable and test expression, make sure they are
437 // valid.
438 bool BeginIsArrow = false;
439 bool EndIsArrow = false;
440 auto [BeginContainerExpr, BeginCallKind] = getContainerFromBeginEndCall(
441 Init: BeginExpr, /*IsBegin=*/true, IsArrow: &BeginIsArrow, IsReverse);
442 if (!BeginContainerExpr)
443 return nullptr;
444
445 auto [EndContainerExpr, EndCallKind] = getContainerFromBeginEndCall(
446 Init: EndExpr, /*IsBegin=*/false, IsArrow: &EndIsArrow, IsReverse);
447 if (BeginCallKind != EndCallKind)
448 return nullptr;
449
450 // Disallow loops that try evil things like this (note the dot and arrow):
451 // for (IteratorType It = Obj.begin(), E = Obj->end(); It != E; ++It) { }
452 if (!EndContainerExpr || BeginIsArrow != EndIsArrow ||
453 !areSameExpr(Context, First: EndContainerExpr, Second: BeginContainerExpr))
454 return nullptr;
455
456 *ContainerNeedsDereference = BeginIsArrow;
457 return BeginContainerExpr;
458}
459
460/// Obtain the original source code text from a SourceRange.
461static StringRef getStringFromRange(SourceManager &SourceMgr,
462 const LangOptions &LangOpts,
463 SourceRange Range) {
464 if (SourceMgr.getFileID(SpellingLoc: Range.getBegin()) !=
465 SourceMgr.getFileID(SpellingLoc: Range.getEnd())) {
466 return {}; // Empty string.
467 }
468
469 return Lexer::getSourceText(Range: CharSourceRange(Range, true), SM: SourceMgr,
470 LangOpts);
471}
472
473/// If the given expression is actually a DeclRefExpr or a MemberExpr,
474/// find and return the underlying ValueDecl; otherwise, return NULL.
475static const ValueDecl *getReferencedVariable(const Expr *E) {
476 if (const DeclRefExpr *DRE = getDeclRef(E))
477 return dyn_cast<VarDecl>(Val: DRE->getDecl());
478 if (const auto *Mem = dyn_cast<MemberExpr>(Val: E->IgnoreParenImpCasts()))
479 return dyn_cast<FieldDecl>(Val: Mem->getMemberDecl());
480 return nullptr;
481}
482
483/// Returns true when the given expression is a member expression
484/// whose base is `this` (implicitly or not).
485static bool isDirectMemberExpr(const Expr *E) {
486 if (const auto *Member = dyn_cast<MemberExpr>(Val: E->IgnoreParenImpCasts()))
487 return isa<CXXThisExpr>(Val: Member->getBase()->IgnoreParenImpCasts());
488 return false;
489}
490
491/// Given an expression that represents an usage of an element from the
492/// container that we are iterating over, returns false when it can be
493/// guaranteed this element cannot be modified as a result of this usage.
494static bool canBeModified(ASTContext *Context, const Expr *E) {
495 if (E->getType().isConstQualified())
496 return false;
497 auto Parents = Context->getParents(Node: *E);
498 if (Parents.size() != 1)
499 return true;
500 if (const auto *Cast = Parents[0].get<ImplicitCastExpr>()) {
501 if ((Cast->getCastKind() == CK_NoOp &&
502 Context->hasSameType(Cast->getType(), E->getType().withConst())) ||
503 (Cast->getCastKind() == CK_LValueToRValue &&
504 !Cast->getType().isNull() && Cast->getType()->isFundamentalType()))
505 return false;
506 }
507 // FIXME: Make this function more generic.
508 return true;
509}
510
511/// Returns true when it can be guaranteed that the elements of the
512/// container are not being modified.
513static bool usagesAreConst(ASTContext *Context, const UsageResult &Usages) {
514 for (const Usage &U : Usages) {
515 // Lambda captures are just redeclarations (VarDecl) of the same variable,
516 // not expressions. If we want to know if a variable that is captured by
517 // reference can be modified in an usage inside the lambda's body, we need
518 // to find the expression corresponding to that particular usage, later in
519 // this loop.
520 if (U.Kind != Usage::UK_CaptureByCopy && U.Kind != Usage::UK_CaptureByRef &&
521 canBeModified(Context, E: U.Expression))
522 return false;
523 }
524 return true;
525}
526
527/// Returns true if the elements of the container are never accessed
528/// by reference.
529static bool usagesReturnRValues(const UsageResult &Usages) {
530 for (const auto &U : Usages) {
531 if (U.Expression && !U.Expression->isPRValue())
532 return false;
533 }
534 return true;
535}
536
537/// Returns true if the container is const-qualified.
538static bool containerIsConst(const Expr *ContainerExpr, bool Dereference) {
539 if (const auto *VDec = getReferencedVariable(E: ContainerExpr)) {
540 QualType CType = VDec->getType();
541 if (Dereference) {
542 if (!CType->isPointerType())
543 return false;
544 CType = CType->getPointeeType();
545 }
546 // If VDec is a reference to a container, Dereference is false,
547 // but we still need to check the const-ness of the underlying container
548 // type.
549 CType = CType.getNonReferenceType();
550 return CType.isConstQualified();
551 }
552 return false;
553}
554
555LoopConvertCheck::LoopConvertCheck(StringRef Name, ClangTidyContext *Context)
556 : ClangTidyCheck(Name, Context), TUInfo(new TUTrackingInfo),
557 MaxCopySize(Options.get(LocalName: "MaxCopySize", Default: 16ULL)),
558 MinConfidence(Options.get(LocalName: "MinConfidence", Default: Confidence::CL_Reasonable)),
559 NamingStyle(Options.get(LocalName: "NamingStyle", Default: VariableNamer::NS_CamelCase)),
560 Inserter(Options.getLocalOrGlobal(LocalName: "IncludeStyle",
561 Default: utils::IncludeSorter::IS_LLVM),
562 areDiagsSelfContained()),
563 UseCxx20IfAvailable(Options.get(LocalName: "UseCxx20ReverseRanges", Default: true)),
564 ReverseFunction(Options.get(LocalName: "MakeReverseRangeFunction", Default: "")),
565 ReverseHeader(Options.get(LocalName: "MakeReverseRangeHeader", Default: "")) {
566
567 if (ReverseFunction.empty() && !ReverseHeader.empty()) {
568 configurationDiag(
569 Description: "modernize-loop-convert: 'MakeReverseRangeHeader' is set but "
570 "'MakeReverseRangeFunction' is not, disabling reverse loop "
571 "transformation");
572 UseReverseRanges = false;
573 } else if (ReverseFunction.empty()) {
574 UseReverseRanges = UseCxx20IfAvailable && getLangOpts().CPlusPlus20;
575 } else {
576 UseReverseRanges = true;
577 }
578}
579
580void LoopConvertCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
581 Options.store(Options&: Opts, LocalName: "MaxCopySize", Value: MaxCopySize);
582 Options.store(Options&: Opts, LocalName: "MinConfidence", Value: MinConfidence);
583 Options.store(Options&: Opts, LocalName: "NamingStyle", Value: NamingStyle);
584 Options.store(Options&: Opts, LocalName: "IncludeStyle", Value: Inserter.getStyle());
585 Options.store(Options&: Opts, LocalName: "UseCxx20ReverseRanges", Value: UseCxx20IfAvailable);
586 Options.store(Options&: Opts, LocalName: "MakeReverseRangeFunction", Value: ReverseFunction);
587 Options.store(Options&: Opts, LocalName: "MakeReverseRangeHeader", Value: ReverseHeader);
588}
589
590void LoopConvertCheck::registerPPCallbacks(const SourceManager &SM,
591 Preprocessor *PP,
592 Preprocessor *ModuleExpanderPP) {
593 Inserter.registerPreprocessor(PP);
594}
595
596void LoopConvertCheck::registerMatchers(MatchFinder *Finder) {
597 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makeArrayLoopMatcher()), Action: this);
598 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makeIteratorLoopMatcher(IsReverse: false)), Action: this);
599 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makePseudoArrayLoopMatcher()), Action: this);
600 if (UseReverseRanges)
601 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makeIteratorLoopMatcher(IsReverse: true)), Action: this);
602}
603
604/// Given the range of a single declaration, such as:
605/// \code
606/// unsigned &ThisIsADeclarationThatCanSpanSeveralLinesOfCode =
607/// InitializationValues[I];
608/// next_instruction;
609/// \endcode
610/// Finds the range that has to be erased to remove this declaration without
611/// leaving empty lines, by extending the range until the beginning of the
612/// next instruction.
613///
614/// We need to delete a potential newline after the deleted alias, as
615/// clang-format will leave empty lines untouched. For all other formatting we
616/// rely on clang-format to fix it.
617void LoopConvertCheck::getAliasRange(SourceManager &SM, SourceRange &Range) {
618 bool Invalid = false;
619 const char *TextAfter =
620 SM.getCharacterData(SL: Range.getEnd().getLocWithOffset(Offset: 1), Invalid: &Invalid);
621 if (Invalid)
622 return;
623 unsigned Offset = std::strspn(s: TextAfter, accept: " \t\r\n");
624 Range =
625 SourceRange(Range.getBegin(), Range.getEnd().getLocWithOffset(Offset));
626}
627
628/// Computes the changes needed to convert a given for loop, and
629/// applies them.
630void LoopConvertCheck::doConversion(
631 ASTContext *Context, const VarDecl *IndexVar,
632 const ValueDecl *MaybeContainer, const UsageResult &Usages,
633 const DeclStmt *AliasDecl, bool AliasUseRequired, bool AliasFromForInit,
634 const ForStmt *Loop, RangeDescriptor Descriptor) {
635 std::string VarNameOrStructuredBinding;
636 bool VarNameFromAlias = (Usages.size() == 1) && AliasDecl;
637 bool AliasVarIsRef = false;
638 bool CanCopy = true;
639 std::vector<FixItHint> FixIts;
640 if (VarNameFromAlias) {
641 const auto *AliasVar = cast<VarDecl>(Val: AliasDecl->getSingleDecl());
642
643 // Handle structured bindings
644 if (const auto *AliasDecompositionDecl =
645 dyn_cast<DecompositionDecl>(Val: AliasDecl->getSingleDecl())) {
646 VarNameOrStructuredBinding = "[";
647
648 assert(!AliasDecompositionDecl->bindings().empty() && "No bindings");
649 for (const BindingDecl *Binding : AliasDecompositionDecl->bindings()) {
650 VarNameOrStructuredBinding += Binding->getName().str() + ", ";
651 }
652
653 VarNameOrStructuredBinding.erase(pos: VarNameOrStructuredBinding.size() - 2,
654 n: 2);
655 VarNameOrStructuredBinding += "]";
656 } else {
657 VarNameOrStructuredBinding = AliasVar->getName().str();
658
659 // Use the type of the alias if it's not the same
660 QualType AliasVarType = AliasVar->getType();
661 assert(!AliasVarType.isNull() && "Type in VarDecl is null");
662 if (AliasVarType->isReferenceType()) {
663 AliasVarType = AliasVarType.getNonReferenceType();
664 AliasVarIsRef = true;
665 }
666 if (Descriptor.ElemType.isNull() ||
667 !Context->hasSameUnqualifiedType(T1: AliasVarType, T2: Descriptor.ElemType))
668 Descriptor.ElemType = AliasVarType;
669 }
670
671 // We keep along the entire DeclStmt to keep the correct range here.
672 SourceRange ReplaceRange = AliasDecl->getSourceRange();
673
674 std::string ReplacementText;
675 if (AliasUseRequired) {
676 ReplacementText = VarNameOrStructuredBinding;
677 } else if (AliasFromForInit) {
678 // FIXME: Clang includes the location of the ';' but only for DeclStmt's
679 // in a for loop's init clause. Need to put this ';' back while removing
680 // the declaration of the alias variable. This is probably a bug.
681 ReplacementText = ";";
682 } else {
683 // Avoid leaving empty lines or trailing whitespaces.
684 getAliasRange(SM&: Context->getSourceManager(), Range&: ReplaceRange);
685 }
686
687 FixIts.push_back(x: FixItHint::CreateReplacement(
688 RemoveRange: CharSourceRange::getTokenRange(R: ReplaceRange), Code: ReplacementText));
689 // No further replacements are made to the loop, since the iterator or index
690 // was used exactly once - in the initialization of AliasVar.
691 } else {
692 VariableNamer Namer(&TUInfo->getGeneratedDecls(),
693 &TUInfo->getParentFinder().getStmtToParentStmtMap(),
694 Loop, IndexVar, MaybeContainer, Context, NamingStyle);
695 VarNameOrStructuredBinding = Namer.createIndexName();
696 // First, replace all usages of the array subscript expression with our new
697 // variable.
698 for (const auto &Usage : Usages) {
699 std::string ReplaceText;
700 SourceRange Range = Usage.Range;
701 if (Usage.Expression) {
702 // If this is an access to a member through the arrow operator, after
703 // the replacement it must be accessed through the '.' operator.
704 ReplaceText = Usage.Kind == Usage::UK_MemberThroughArrow
705 ? VarNameOrStructuredBinding + "."
706 : VarNameOrStructuredBinding;
707 const DynTypedNodeList Parents = Context->getParents(Node: *Usage.Expression);
708 if (Parents.size() == 1) {
709 if (const auto *Paren = Parents[0].get<ParenExpr>()) {
710 // Usage.Expression will be replaced with the new index variable,
711 // and parenthesis around a simple DeclRefExpr can always be
712 // removed except in case of a `sizeof` operator call.
713 const DynTypedNodeList GrandParents = Context->getParents(Node: *Paren);
714 if (GrandParents.size() != 1 ||
715 GrandParents[0].get<UnaryExprOrTypeTraitExpr>() == nullptr) {
716 Range = Paren->getSourceRange();
717 }
718 } else if (const auto *UOP = Parents[0].get<UnaryOperator>()) {
719 // If we are taking the address of the loop variable, then we must
720 // not use a copy, as it would mean taking the address of the loop's
721 // local index instead.
722 // FIXME: This won't catch cases where the address is taken outside
723 // of the loop's body (for instance, in a function that got the
724 // loop's index as a const reference parameter), or where we take
725 // the address of a member (like "&Arr[i].A.B.C").
726 if (UOP->getOpcode() == UO_AddrOf)
727 CanCopy = false;
728 }
729 }
730 } else {
731 // The Usage expression is only null in case of lambda captures (which
732 // are VarDecl). If the index is captured by value, add '&' to capture
733 // by reference instead.
734 ReplaceText = Usage.Kind == Usage::UK_CaptureByCopy
735 ? "&" + VarNameOrStructuredBinding
736 : VarNameOrStructuredBinding;
737 }
738 TUInfo->getReplacedVars().insert(KV: std::make_pair(x&: Loop, y&: IndexVar));
739 FixIts.push_back(x: FixItHint::CreateReplacement(
740 RemoveRange: CharSourceRange::getTokenRange(R: Range), Code: ReplaceText));
741 }
742 }
743
744 // Now, we need to construct the new range expression.
745 SourceRange ParenRange(Loop->getLParenLoc(), Loop->getRParenLoc());
746
747 QualType Type = Context->getAutoDeductType();
748 if (!Descriptor.ElemType.isNull() && Descriptor.ElemType->isFundamentalType())
749 Type = Descriptor.ElemType.getUnqualifiedType();
750 Type = Type.getDesugaredType(Context: *Context);
751
752 // If the new variable name is from the aliased variable, then the reference
753 // type for the new variable should only be used if the aliased variable was
754 // declared as a reference.
755 bool IsCheapToCopy =
756 !Descriptor.ElemType.isNull() &&
757 Descriptor.ElemType.isTriviallyCopyableType(*Context) &&
758 !Descriptor.ElemType->isDependentSizedArrayType() &&
759 // TypeInfo::Width is in bits.
760 Context->getTypeInfo(Descriptor.ElemType).Width <= 8 * MaxCopySize;
761 bool UseCopy = CanCopy && ((VarNameFromAlias && !AliasVarIsRef) ||
762 (Descriptor.DerefByConstRef && IsCheapToCopy));
763
764 if (!UseCopy) {
765 if (Descriptor.DerefByConstRef) {
766 Type = Context->getLValueReferenceType(T: Context->getConstType(T: Type));
767 } else if (Descriptor.DerefByValue) {
768 if (!IsCheapToCopy)
769 Type = Context->getRValueReferenceType(T: Type);
770 } else {
771 Type = Context->getLValueReferenceType(T: Type);
772 }
773 }
774
775 SmallString<128> Range;
776 llvm::raw_svector_ostream Output(Range);
777 Output << '(';
778 Type.print(OS&: Output, Policy: getLangOpts());
779 Output << ' ' << VarNameOrStructuredBinding << " : ";
780 if (Descriptor.NeedsReverseCall)
781 Output << getReverseFunction() << '(';
782 if (Descriptor.ContainerNeedsDereference)
783 Output << '*';
784 Output << Descriptor.ContainerString;
785 if (Descriptor.NeedsReverseCall)
786 Output << "))";
787 else
788 Output << ')';
789 FixIts.push_back(x: FixItHint::CreateReplacement(
790 RemoveRange: CharSourceRange::getTokenRange(R: ParenRange), Code: Range));
791
792 if (Descriptor.NeedsReverseCall && !getReverseHeader().empty()) {
793 if (std::optional<FixItHint> Insertion = Inserter.createIncludeInsertion(
794 FileID: Context->getSourceManager().getFileID(SpellingLoc: Loop->getBeginLoc()),
795 Header: getReverseHeader()))
796 FixIts.push_back(x: *Insertion);
797 }
798 diag(Loc: Loop->getForLoc(), Description: "use range-based for loop instead") << FixIts;
799 TUInfo->getGeneratedDecls().insert(
800 KV: make_pair(x&: Loop, y&: VarNameOrStructuredBinding));
801}
802
803/// Returns a string which refers to the container iterated over.
804StringRef LoopConvertCheck::getContainerString(ASTContext *Context,
805 const ForStmt *Loop,
806 const Expr *ContainerExpr) {
807 StringRef ContainerString;
808 ContainerExpr = ContainerExpr->IgnoreParenImpCasts();
809 if (isa<CXXThisExpr>(Val: ContainerExpr)) {
810 ContainerString = "this";
811 } else {
812 // For CXXOperatorCallExpr such as vector_ptr->size() we want the class
813 // object vector_ptr, but for vector[2] we need the whole expression.
814 if (const auto *E = dyn_cast<CXXOperatorCallExpr>(Val: ContainerExpr))
815 if (E->getOperator() != OO_Subscript)
816 ContainerExpr = E->getArg(0);
817 ContainerString =
818 getStringFromRange(Context->getSourceManager(), Context->getLangOpts(),
819 ContainerExpr->getSourceRange());
820 }
821
822 return ContainerString;
823}
824
825/// Determines what kind of 'auto' must be used after converting a for
826/// loop that iterates over an array or pseudoarray.
827void LoopConvertCheck::getArrayLoopQualifiers(ASTContext *Context,
828 const BoundNodes &Nodes,
829 const Expr *ContainerExpr,
830 const UsageResult &Usages,
831 RangeDescriptor &Descriptor) {
832 // On arrays and pseudoarrays, we must figure out the qualifiers from the
833 // usages.
834 if (usagesAreConst(Context, Usages) ||
835 containerIsConst(ContainerExpr, Dereference: Descriptor.ContainerNeedsDereference)) {
836 Descriptor.DerefByConstRef = true;
837 }
838 if (usagesReturnRValues(Usages)) {
839 // If the index usages (dereference, subscript, at, ...) return rvalues,
840 // then we should not use a reference, because we need to keep the code
841 // correct if it mutates the returned objects.
842 Descriptor.DerefByValue = true;
843 }
844 // Try to find the type of the elements on the container, to check if
845 // they are trivially copyable.
846 for (const Usage &U : Usages) {
847 if (!U.Expression || U.Expression->getType().isNull())
848 continue;
849 QualType Type = U.Expression->getType().getCanonicalType();
850 if (U.Kind == Usage::UK_MemberThroughArrow) {
851 if (!Type->isPointerType()) {
852 continue;
853 }
854 Type = Type->getPointeeType();
855 }
856 Descriptor.ElemType = Type;
857 }
858}
859
860/// Determines what kind of 'auto' must be used after converting an
861/// iterator based for loop.
862void LoopConvertCheck::getIteratorLoopQualifiers(ASTContext *Context,
863 const BoundNodes &Nodes,
864 RangeDescriptor &Descriptor) {
865 // The matchers for iterator loops provide bound nodes to obtain this
866 // information.
867 const auto *InitVar = Nodes.getNodeAs<VarDecl>(ID: InitVarName);
868 QualType CanonicalInitVarType = InitVar->getType().getCanonicalType();
869 const auto *DerefByValueType =
870 Nodes.getNodeAs<QualType>(ID: DerefByValueResultName);
871 Descriptor.DerefByValue = DerefByValueType;
872
873 if (Descriptor.DerefByValue) {
874 // If the dereference operator returns by value then test for the
875 // canonical const qualification of the init variable type.
876 Descriptor.DerefByConstRef = CanonicalInitVarType.isConstQualified();
877 Descriptor.ElemType = *DerefByValueType;
878 } else {
879 if (const auto *DerefType =
880 Nodes.getNodeAs<QualType>(ID: DerefByRefResultName)) {
881 // A node will only be bound with DerefByRefResultName if we're dealing
882 // with a user-defined iterator type. Test the const qualification of
883 // the reference type.
884 auto ValueType = DerefType->getNonReferenceType();
885
886 Descriptor.DerefByConstRef = ValueType.isConstQualified();
887 Descriptor.ElemType = ValueType;
888 } else {
889 // By nature of the matcher this case is triggered only for built-in
890 // iterator types (i.e. pointers).
891 assert(isa<PointerType>(CanonicalInitVarType) &&
892 "Non-class iterator type is not a pointer type");
893
894 // We test for const qualification of the pointed-at type.
895 Descriptor.DerefByConstRef =
896 CanonicalInitVarType->getPointeeType().isConstQualified();
897 Descriptor.ElemType = CanonicalInitVarType->getPointeeType();
898 }
899 }
900}
901
902/// Determines the parameters needed to build the range replacement.
903void LoopConvertCheck::determineRangeDescriptor(
904 ASTContext *Context, const BoundNodes &Nodes, const ForStmt *Loop,
905 LoopFixerKind FixerKind, const Expr *ContainerExpr,
906 const UsageResult &Usages, RangeDescriptor &Descriptor) {
907 Descriptor.ContainerString =
908 std::string(getContainerString(Context, Loop, ContainerExpr));
909 Descriptor.NeedsReverseCall = (FixerKind == LFK_ReverseIterator);
910
911 if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator)
912 getIteratorLoopQualifiers(Context, Nodes, Descriptor);
913 else
914 getArrayLoopQualifiers(Context, Nodes, ContainerExpr, Usages, Descriptor);
915}
916
917/// Check some of the conditions that must be met for the loop to be
918/// convertible.
919bool LoopConvertCheck::isConvertible(ASTContext *Context,
920 const ast_matchers::BoundNodes &Nodes,
921 const ForStmt *Loop,
922 LoopFixerKind FixerKind) {
923 // In self contained diagnostic mode we don't want dependencies on other
924 // loops, otherwise, If we already modified the range of this for loop, don't
925 // do any further updates on this iteration.
926 if (areDiagsSelfContained())
927 TUInfo = std::make_unique<TUTrackingInfo>();
928 else if (TUInfo->getReplacedVars().count(Val: Loop))
929 return false;
930
931 // Check that we have exactly one index variable and at most one end variable.
932 const auto *InitVar = Nodes.getNodeAs<VarDecl>(ID: InitVarName);
933
934 // FIXME: Try to put most of this logic inside a matcher.
935 if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator) {
936 QualType InitVarType = InitVar->getType();
937 QualType CanonicalInitVarType = InitVarType.getCanonicalType();
938
939 const auto *BeginCall = Nodes.getNodeAs<CallExpr>(ID: BeginCallName);
940 assert(BeginCall && "Bad Callback. No begin call expression");
941 QualType CanonicalBeginType =
942 BeginCall->getDirectCallee()->getReturnType().getCanonicalType();
943 if (CanonicalBeginType->isPointerType() &&
944 CanonicalInitVarType->isPointerType()) {
945 // If the initializer and the variable are both pointers check if the
946 // un-qualified pointee types match, otherwise we don't use auto.
947 return Context->hasSameUnqualifiedType(
948 T1: CanonicalBeginType->getPointeeType(),
949 T2: CanonicalInitVarType->getPointeeType());
950 }
951
952 if (CanonicalBeginType->isBuiltinType() ||
953 CanonicalInitVarType->isBuiltinType())
954 return false;
955
956 } else if (FixerKind == LFK_PseudoArray) {
957 if (const auto *EndCall = Nodes.getNodeAs<CXXMemberCallExpr>(ID: EndCallName)) {
958 // This call is required to obtain the container.
959 if (!isa<MemberExpr>(EndCall->getCallee()))
960 return false;
961 }
962 return Nodes.getNodeAs<CallExpr>(ID: EndCallName) != nullptr;
963 }
964 return true;
965}
966
967void LoopConvertCheck::check(const MatchFinder::MatchResult &Result) {
968 const BoundNodes &Nodes = Result.Nodes;
969 Confidence ConfidenceLevel(Confidence::CL_Safe);
970 ASTContext *Context = Result.Context;
971
972 const ForStmt *Loop = nullptr;
973 LoopFixerKind FixerKind{};
974 RangeDescriptor Descriptor;
975
976 if ((Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNameArray))) {
977 FixerKind = LFK_Array;
978 } else if ((Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNameIterator))) {
979 FixerKind = LFK_Iterator;
980 } else if ((Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNameReverseIterator))) {
981 FixerKind = LFK_ReverseIterator;
982 } else {
983 Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNamePseudoArray);
984 assert(Loop && "Bad Callback. No for statement");
985 FixerKind = LFK_PseudoArray;
986 }
987
988 if (!isConvertible(Context, Nodes, Loop, FixerKind))
989 return;
990
991 const auto *LoopVar = Nodes.getNodeAs<VarDecl>(ID: InitVarName);
992 const auto *EndVar = Nodes.getNodeAs<VarDecl>(ID: EndVarName);
993
994 // If the loop calls end()/size() after each iteration, lower our confidence
995 // level.
996 if (FixerKind != LFK_Array && !EndVar)
997 ConfidenceLevel.lowerTo(Level: Confidence::CL_Reasonable);
998
999 // If the end comparison isn't a variable, we can try to work with the
1000 // expression the loop variable is being tested against instead.
1001 const auto *EndCall = Nodes.getNodeAs<Expr>(ID: EndCallName);
1002 const auto *BoundExpr = Nodes.getNodeAs<Expr>(ID: ConditionBoundName);
1003
1004 // Find container expression of iterators and pseudoarrays, and determine if
1005 // this expression needs to be dereferenced to obtain the container.
1006 // With array loops, the container is often discovered during the
1007 // ForLoopIndexUseVisitor traversal.
1008 const Expr *ContainerExpr = nullptr;
1009 if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator) {
1010 ContainerExpr = findContainer(
1011 Context, BeginExpr: LoopVar->getInit(), EndExpr: EndVar ? EndVar->getInit() : EndCall,
1012 ContainerNeedsDereference: &Descriptor.ContainerNeedsDereference,
1013 /*IsReverse=*/FixerKind == LFK_ReverseIterator);
1014 } else if (FixerKind == LFK_PseudoArray) {
1015 std::optional<ContainerCall> Call = getContainerExpr(Call: EndCall);
1016 if (Call) {
1017 ContainerExpr = Call->Container;
1018 Descriptor.ContainerNeedsDereference = Call->IsArrow;
1019 }
1020 }
1021
1022 // We must know the container or an array length bound.
1023 if (!ContainerExpr && !BoundExpr)
1024 return;
1025
1026 ForLoopIndexUseVisitor Finder(Context, LoopVar, EndVar, ContainerExpr,
1027 BoundExpr,
1028 Descriptor.ContainerNeedsDereference);
1029
1030 // Find expressions and variables on which the container depends.
1031 if (ContainerExpr) {
1032 ComponentFinderASTVisitor ComponentFinder;
1033 ComponentFinder.findExprComponents(SourceExpr: ContainerExpr->IgnoreParenImpCasts());
1034 Finder.addComponents(Components: ComponentFinder.getComponents());
1035 }
1036
1037 // Find usages of the loop index. If they are not used in a convertible way,
1038 // stop here.
1039 if (!Finder.findAndVerifyUsages(Body: Loop->getBody()))
1040 return;
1041 ConfidenceLevel.lowerTo(Level: Finder.getConfidenceLevel());
1042
1043 // Obtain the container expression, if we don't have it yet.
1044 if (FixerKind == LFK_Array) {
1045 ContainerExpr = Finder.getContainerIndexed()->IgnoreParenImpCasts();
1046
1047 // Very few loops are over expressions that generate arrays rather than
1048 // array variables. Consider loops over arrays that aren't just represented
1049 // by a variable to be risky conversions.
1050 if (!getReferencedVariable(E: ContainerExpr) &&
1051 !isDirectMemberExpr(E: ContainerExpr))
1052 ConfidenceLevel.lowerTo(Level: Confidence::CL_Risky);
1053 }
1054
1055 // Find out which qualifiers we have to use in the loop range.
1056 TraversalKindScope RAII(*Context, TK_AsIs);
1057 const UsageResult &Usages = Finder.getUsages();
1058 determineRangeDescriptor(Context, Nodes, Loop, FixerKind, ContainerExpr,
1059 Usages, Descriptor);
1060
1061 // Ensure that we do not try to move an expression dependent on a local
1062 // variable declared inside the loop outside of it.
1063 // FIXME: Determine when the external dependency isn't an expression converted
1064 // by another loop.
1065 TUInfo->getParentFinder().gatherAncestors(Ctx&: *Context);
1066 DependencyFinderASTVisitor DependencyFinder(
1067 &TUInfo->getParentFinder().getStmtToParentStmtMap(),
1068 &TUInfo->getParentFinder().getDeclToParentStmtMap(),
1069 &TUInfo->getReplacedVars(), Loop);
1070
1071 if (DependencyFinder.dependsOnInsideVariable(ContainerExpr) ||
1072 Descriptor.ContainerString.empty() || Usages.empty() ||
1073 ConfidenceLevel.getLevel() < MinConfidence)
1074 return;
1075
1076 doConversion(Context, IndexVar: LoopVar, MaybeContainer: getReferencedVariable(E: ContainerExpr), Usages,
1077 AliasDecl: Finder.getAliasDecl(), AliasUseRequired: Finder.aliasUseRequired(),
1078 AliasFromForInit: Finder.aliasFromForInit(), Loop, Descriptor);
1079}
1080
1081llvm::StringRef LoopConvertCheck::getReverseFunction() const {
1082 if (!ReverseFunction.empty())
1083 return ReverseFunction;
1084 if (UseReverseRanges)
1085 return "std::ranges::reverse_view";
1086 return "";
1087}
1088
1089llvm::StringRef LoopConvertCheck::getReverseHeader() const {
1090 if (!ReverseHeader.empty())
1091 return ReverseHeader;
1092 if (UseReverseRanges && ReverseFunction.empty()) {
1093 return "<ranges>";
1094 }
1095 return "";
1096}
1097
1098} // namespace modernize
1099} // namespace clang::tidy
1100

source code of clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp