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/Casting.h"
22#include "llvm/Support/raw_ostream.h"
23#include <cassert>
24#include <cstring>
25#include <optional>
26#include <tuple>
27#include <utility>
28
29using namespace clang::ast_matchers;
30using namespace llvm;
31
32namespace clang::tidy {
33
34template <> struct OptionEnumMapping<modernize::Confidence::Level> {
35 static llvm::ArrayRef<std::pair<modernize::Confidence::Level, StringRef>>
36 getEnumMapping() {
37 static constexpr std::pair<modernize::Confidence::Level, StringRef>
38 Mapping[] = {{modernize::Confidence::CL_Reasonable, "reasonable"},
39 {modernize::Confidence::CL_Safe, "safe"},
40 {modernize::Confidence::CL_Risky, "risky"}};
41 return {Mapping};
42 }
43};
44
45template <> struct OptionEnumMapping<modernize::VariableNamer::NamingStyle> {
46 static llvm::ArrayRef<
47 std::pair<modernize::VariableNamer::NamingStyle, StringRef>>
48 getEnumMapping() {
49 static constexpr std::pair<modernize::VariableNamer::NamingStyle, StringRef>
50 Mapping[] = {{modernize::VariableNamer::NS_CamelCase, "CamelCase"},
51 {modernize::VariableNamer::NS_CamelBack, "camelBack"},
52 {modernize::VariableNamer::NS_LowerCase, "lower_case"},
53 {modernize::VariableNamer::NS_UpperCase, "UPPER_CASE"}};
54 return {Mapping};
55 }
56};
57
58namespace modernize {
59
60static const char LoopNameArray[] = "forLoopArray";
61static const char LoopNameIterator[] = "forLoopIterator";
62static const char LoopNameReverseIterator[] = "forLoopReverseIterator";
63static const char LoopNamePseudoArray[] = "forLoopPseudoArray";
64static const char ConditionBoundName[] = "conditionBound";
65static const char InitVarName[] = "initVar";
66static const char BeginCallName[] = "beginCall";
67static const char EndCallName[] = "endCall";
68static const char EndVarName[] = "endVar";
69static const char DerefByValueResultName[] = "derefByValueResult";
70static const char DerefByRefResultName[] = "derefByRefResult";
71static const llvm::StringSet<> MemberNames{"begin", "cbegin", "rbegin",
72 "crbegin", "end", "cend",
73 "rend", "crend", "size"};
74static const llvm::StringSet<> ADLNames{"begin", "cbegin", "rbegin",
75 "crbegin", "end", "cend",
76 "rend", "crend", "size"};
77static const llvm::StringSet<> StdNames{
78 "std::begin", "std::cbegin", "std::rbegin", "std::crbegin", "std::end",
79 "std::cend", "std::rend", "std::crend", "std::size"};
80
81static StatementMatcher integerComparisonMatcher() {
82 return expr(ignoringParenImpCasts(
83 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName))))));
84}
85
86static DeclarationMatcher initToZeroMatcher() {
87 return varDecl(
88 hasInitializer(InnerMatcher: ignoringParenImpCasts(InnerMatcher: integerLiteral(equals(Value: 0)))))
89 .bind(ID: InitVarName);
90}
91
92static StatementMatcher incrementVarMatcher() {
93 return declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName))));
94}
95
96static StatementMatcher
97arrayConditionMatcher(internal::Matcher<Expr> LimitExpr) {
98 return binaryOperator(
99 anyOf(allOf(hasOperatorName(Name: "<"), hasLHS(InnerMatcher: integerComparisonMatcher()),
100 hasRHS(InnerMatcher: LimitExpr)),
101 allOf(hasOperatorName(Name: ">"), hasLHS(InnerMatcher: LimitExpr),
102 hasRHS(InnerMatcher: integerComparisonMatcher())),
103 allOf(hasOperatorName(Name: "!="),
104 hasOperands(Matcher1: integerComparisonMatcher(), Matcher2: LimitExpr))));
105}
106
107/// The matcher for loops over arrays.
108/// \code
109/// for (int i = 0; i < 3 + 2; ++i) { ... }
110/// \endcode
111/// The following string identifiers are bound to these parts of the AST:
112/// ConditionBoundName: '3 + 2' (as an Expr)
113/// InitVarName: 'i' (as a VarDecl)
114/// LoopName: The entire for loop (as a ForStmt)
115///
116/// Client code will need to make sure that:
117/// - The index variable is only used as an array index.
118/// - All arrays indexed by the loop are the same.
119StatementMatcher makeArrayLoopMatcher() {
120 StatementMatcher ArrayBoundMatcher =
121 expr(hasType(InnerMatcher: isInteger())).bind(ID: ConditionBoundName);
122
123 return forStmt(unless(isInTemplateInstantiation()),
124 hasLoopInit(InnerMatcher: declStmt(hasSingleDecl(InnerMatcher: initToZeroMatcher()))),
125 hasCondition(InnerMatcher: arrayConditionMatcher(LimitExpr: ArrayBoundMatcher)),
126 hasIncrement(
127 InnerMatcher: unaryOperator(hasOperatorName(Name: "++"),
128 hasUnaryOperand(InnerMatcher: incrementVarMatcher()))))
129 .bind(ID: LoopNameArray);
130}
131
132/// The matcher used for iterator-based for loops.
133///
134/// This matcher is more flexible than array-based loops. It will match
135/// catch loops of the following textual forms (regardless of whether the
136/// iterator type is actually a pointer type or a class type):
137///
138/// \code
139/// for (containerType::iterator it = container.begin(),
140/// e = createIterator(); it != e; ++it) { ... }
141/// for (containerType::iterator it = container.begin();
142/// it != anotherContainer.end(); ++it) { ... }
143/// for (containerType::iterator it = begin(container),
144/// e = end(container); it != e; ++it) { ... }
145/// for (containerType::iterator it = std::begin(container),
146/// e = std::end(container); it != e; ++it) { ... }
147/// \endcode
148/// The following string identifiers are bound to the parts of the AST:
149/// InitVarName: 'it' (as a VarDecl)
150/// LoopName: The entire for loop (as a ForStmt)
151/// In the first example only:
152/// EndVarName: 'e' (as a VarDecl)
153/// In the second example only:
154/// EndCallName: 'container.end()' (as a CXXMemberCallExpr)
155/// In the third/fourth examples:
156/// 'end(container)' or 'std::end(container)' (as a CallExpr)
157///
158/// Client code will need to make sure that:
159/// - The two containers on which 'begin' and 'end' are called are the same.
160StatementMatcher makeIteratorLoopMatcher(bool IsReverse) {
161
162 auto BeginNameMatcher = IsReverse ? hasAnyName("rbegin", "crbegin")
163 : hasAnyName("begin", "cbegin");
164 auto BeginNameMatcherStd = IsReverse
165 ? hasAnyName("::std::rbegin", "::std::crbegin")
166 : hasAnyName("::std::begin", "::std::cbegin");
167
168 auto EndNameMatcher =
169 IsReverse ? hasAnyName("rend", "crend") : hasAnyName("end", "cend");
170 auto EndNameMatcherStd = IsReverse ? hasAnyName("::std::rend", "::std::crend")
171 : hasAnyName("::std::end", "::std::cend");
172
173 StatementMatcher BeginCallMatcher =
174 expr(anyOf(cxxMemberCallExpr(argumentCountIs(N: 0),
175 callee(InnerMatcher: cxxMethodDecl(BeginNameMatcher))),
176 callExpr(argumentCountIs(N: 1),
177 callee(InnerMatcher: functionDecl(BeginNameMatcher)), usesADL()),
178 callExpr(argumentCountIs(N: 1),
179 callee(InnerMatcher: functionDecl(BeginNameMatcherStd)))))
180 .bind(ID: BeginCallName);
181
182 DeclarationMatcher InitDeclMatcher =
183 varDecl(hasInitializer(InnerMatcher: anyOf(ignoringParenImpCasts(InnerMatcher: BeginCallMatcher),
184 materializeTemporaryExpr(
185 ignoringParenImpCasts(InnerMatcher: BeginCallMatcher)),
186 hasDescendant(BeginCallMatcher))))
187 .bind(ID: InitVarName);
188
189 DeclarationMatcher EndDeclMatcher =
190 varDecl(hasInitializer(InnerMatcher: anything())).bind(ID: EndVarName);
191
192 StatementMatcher EndCallMatcher = expr(anyOf(
193 cxxMemberCallExpr(argumentCountIs(N: 0),
194 callee(InnerMatcher: cxxMethodDecl(EndNameMatcher))),
195 callExpr(argumentCountIs(N: 1), callee(InnerMatcher: functionDecl(EndNameMatcher)),
196 usesADL()),
197 callExpr(argumentCountIs(N: 1), callee(InnerMatcher: functionDecl(EndNameMatcherStd)))));
198
199 StatementMatcher IteratorBoundMatcher =
200 expr(anyOf(ignoringParenImpCasts(
201 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: EndVarName))))),
202 ignoringParenImpCasts(InnerMatcher: expr(EndCallMatcher).bind(ID: EndCallName)),
203 materializeTemporaryExpr(ignoringParenImpCasts(
204 InnerMatcher: expr(EndCallMatcher).bind(ID: EndCallName)))));
205
206 StatementMatcher IteratorComparisonMatcher = expr(ignoringParenImpCasts(
207 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName))))));
208
209 // This matcher tests that a declaration is a CXXRecordDecl that has an
210 // overloaded operator*(). If the operator*() returns by value instead of by
211 // reference then the return type is tagged with DerefByValueResultName.
212 internal::Matcher<VarDecl> TestDerefReturnsByValue =
213 hasType(InnerMatcher: hasUnqualifiedDesugaredType(
214 InnerMatcher: recordType(hasDeclaration(InnerMatcher: cxxRecordDecl(hasMethod(InnerMatcher: cxxMethodDecl(
215 hasOverloadedOperatorName(Name: "*"),
216 anyOf(
217 // Tag the return type if it's by value.
218 returns(InnerMatcher: qualType(unless(hasCanonicalType(InnerMatcher: referenceType())))
219 .bind(ID: DerefByValueResultName)),
220 returns(
221 // Skip loops where the iterator's operator* returns an
222 // rvalue reference. This is just weird.
223 InnerMatcher: qualType(unless(hasCanonicalType(InnerMatcher: rValueReferenceType())))
224 .bind(ID: DerefByRefResultName))))))))));
225
226 return forStmt(
227 unless(isInTemplateInstantiation()),
228 hasLoopInit(InnerMatcher: anyOf(declStmt(declCountIs(N: 2),
229 containsDeclaration(N: 0, InnerMatcher: InitDeclMatcher),
230 containsDeclaration(N: 1, InnerMatcher: EndDeclMatcher)),
231 declStmt(hasSingleDecl(InnerMatcher: InitDeclMatcher)))),
232 hasCondition(InnerMatcher: ignoringImplicit(InnerMatcher: binaryOperation(
233 hasOperatorName(Name: "!="), hasOperands(Matcher1: IteratorComparisonMatcher,
234 Matcher2: IteratorBoundMatcher)))),
235 hasIncrement(InnerMatcher: anyOf(
236 unaryOperator(hasOperatorName(Name: "++"),
237 hasUnaryOperand(InnerMatcher: declRefExpr(
238 to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName)))))),
239 cxxOperatorCallExpr(
240 hasOverloadedOperatorName(Name: "++"),
241 hasArgument(N: 0, InnerMatcher: declRefExpr(to(
242 InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName),
243 TestDerefReturnsByValue))))))))
244 .bind(ID: IsReverse ? LoopNameReverseIterator : LoopNameIterator);
245}
246
247/// The matcher used for array-like containers (pseudoarrays).
248///
249/// This matcher is more flexible than array-based loops. It will match
250/// loops of the following textual forms (regardless of whether the
251/// iterator type is actually a pointer type or a class type):
252///
253/// \code
254/// for (int i = 0, j = container.size(); i < j; ++i) { ... }
255/// for (int i = 0; i < container.size(); ++i) { ... }
256/// for (int i = 0; i < size(container); ++i) { ... }
257/// \endcode
258/// The following string identifiers are bound to the parts of the AST:
259/// InitVarName: 'i' (as a VarDecl)
260/// LoopName: The entire for loop (as a ForStmt)
261/// In the first example only:
262/// EndVarName: 'j' (as a VarDecl)
263/// In the second example only:
264/// EndCallName: 'container.size()' (as a CXXMemberCallExpr) or
265/// 'size(contaner)' (as a CallExpr)
266///
267/// Client code will need to make sure that:
268/// - The containers on which 'size()' is called is the container indexed.
269/// - The index variable is only used in overloaded operator[] or
270/// container.at().
271/// - The container's iterators would not be invalidated during the loop.
272StatementMatcher makePseudoArrayLoopMatcher() {
273 // Test that the incoming type has a record declaration that has methods
274 // called 'begin' and 'end'. If the incoming type is const, then make sure
275 // these methods are also marked const.
276 //
277 // FIXME: To be completely thorough this matcher should also ensure the
278 // return type of begin/end is an iterator that dereferences to the same as
279 // what operator[] or at() returns. Such a test isn't likely to fail except
280 // for pathological cases.
281 //
282 // FIXME: Also, a record doesn't necessarily need begin() and end(). Free
283 // functions called begin() and end() taking the container as an argument
284 // are also allowed.
285 TypeMatcher RecordWithBeginEnd = qualType(anyOf(
286 qualType(isConstQualified(),
287 hasUnqualifiedDesugaredType(InnerMatcher: recordType(hasDeclaration(
288 InnerMatcher: cxxRecordDecl(isSameOrDerivedFrom(Base: cxxRecordDecl(
289 hasMethod(InnerMatcher: cxxMethodDecl(hasName(Name: "begin"), isConst())),
290 hasMethod(InnerMatcher: cxxMethodDecl(hasName(Name: "end"),
291 isConst())))))) // hasDeclaration
292 ))), // qualType
293 qualType(unless(isConstQualified()),
294 hasUnqualifiedDesugaredType(InnerMatcher: recordType(hasDeclaration(
295 InnerMatcher: cxxRecordDecl(isSameOrDerivedFrom(Base: cxxRecordDecl(
296 hasMethod(InnerMatcher: hasName(Name: "begin")),
297 hasMethod(InnerMatcher: hasName(Name: "end"))))))))) // qualType
298 ));
299
300 StatementMatcher SizeCallMatcher = expr(anyOf(
301 cxxMemberCallExpr(argumentCountIs(N: 0),
302 callee(InnerMatcher: cxxMethodDecl(hasAnyName("size", "length"))),
303 on(InnerMatcher: anyOf(hasType(InnerMatcher: pointsTo(InnerMatcher: RecordWithBeginEnd)),
304 hasType(InnerMatcher: RecordWithBeginEnd)))),
305 callExpr(argumentCountIs(N: 1), callee(InnerMatcher: functionDecl(hasName(Name: "size"))),
306 usesADL()),
307 callExpr(argumentCountIs(N: 1),
308 callee(InnerMatcher: functionDecl(hasName(Name: "::std::size"))))));
309
310 StatementMatcher EndInitMatcher =
311 expr(anyOf(ignoringParenImpCasts(InnerMatcher: expr(SizeCallMatcher).bind(ID: EndCallName)),
312 explicitCastExpr(hasSourceExpression(InnerMatcher: ignoringParenImpCasts(
313 InnerMatcher: expr(SizeCallMatcher).bind(ID: EndCallName))))));
314
315 DeclarationMatcher EndDeclMatcher =
316 varDecl(hasInitializer(InnerMatcher: EndInitMatcher)).bind(ID: EndVarName);
317
318 StatementMatcher IndexBoundMatcher =
319 expr(anyOf(ignoringParenImpCasts(
320 InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: EndVarName))))),
321 EndInitMatcher));
322
323 return forStmt(unless(isInTemplateInstantiation()),
324 hasLoopInit(
325 InnerMatcher: anyOf(declStmt(declCountIs(N: 2),
326 containsDeclaration(N: 0, InnerMatcher: initToZeroMatcher()),
327 containsDeclaration(N: 1, InnerMatcher: EndDeclMatcher)),
328 declStmt(hasSingleDecl(InnerMatcher: initToZeroMatcher())))),
329 hasCondition(InnerMatcher: arrayConditionMatcher(LimitExpr: IndexBoundMatcher)),
330 hasIncrement(
331 InnerMatcher: unaryOperator(hasOperatorName(Name: "++"),
332 hasUnaryOperand(InnerMatcher: incrementVarMatcher()))))
333 .bind(ID: LoopNamePseudoArray);
334}
335
336enum class IteratorCallKind {
337 ICK_Member,
338 ICK_ADL,
339 ICK_Std,
340};
341
342struct ContainerCall {
343 const Expr *Container;
344 StringRef Name;
345 bool IsArrow;
346 IteratorCallKind CallKind;
347};
348
349// Find the Expr likely initializing an iterator.
350//
351// Call is either a CXXMemberCallExpr ('c.begin()') or CallExpr of a free
352// function with the first argument as a container ('begin(c)'), or nullptr.
353// Returns at a 3-tuple with the container expr, function name (begin/end/etc),
354// and whether the call is made through an arrow (->) for CXXMemberCallExprs.
355// The returned Expr* is nullptr if any of the assumptions are not met.
356// static std::tuple<const Expr *, StringRef, bool, IteratorCallKind>
357static std::optional<ContainerCall> getContainerExpr(const Expr *Call) {
358 const Expr *Dug = digThroughConstructorsConversions(E: Call);
359
360 IteratorCallKind CallKind = IteratorCallKind::ICK_Member;
361
362 if (const auto *TheCall = dyn_cast_or_null<CXXMemberCallExpr>(Val: Dug)) {
363 CallKind = IteratorCallKind::ICK_Member;
364 if (const auto *Member = dyn_cast<MemberExpr>(TheCall->getCallee())) {
365 if (Member->getMemberDecl() == nullptr ||
366 !MemberNames.contains(key: Member->getMemberDecl()->getName()))
367 return std::nullopt;
368 return ContainerCall{TheCall->getImplicitObjectArgument(),
369 Member->getMemberDecl()->getName(),
370 Member->isArrow(), CallKind};
371 }
372 if (TheCall->getDirectCallee() == nullptr ||
373 !MemberNames.contains(key: TheCall->getDirectCallee()->getName()))
374 return std::nullopt;
375 return ContainerCall{TheCall->getArg(0),
376 TheCall->getDirectCallee()->getName(), false,
377 CallKind};
378 }
379 if (const auto *TheCall = dyn_cast_or_null<CallExpr>(Val: Dug)) {
380 if (TheCall->getNumArgs() != 1)
381 return std::nullopt;
382
383 if (TheCall->usesADL()) {
384 if (TheCall->getDirectCallee() == nullptr ||
385 !ADLNames.contains(key: TheCall->getDirectCallee()->getName()))
386 return std::nullopt;
387 CallKind = IteratorCallKind::ICK_ADL;
388 } else {
389 if (!StdNames.contains(
390 key: TheCall->getDirectCallee()->getQualifiedNameAsString()))
391 return std::nullopt;
392 CallKind = IteratorCallKind::ICK_Std;
393 }
394
395 if (TheCall->getDirectCallee() == nullptr)
396 return std::nullopt;
397
398 return ContainerCall{TheCall->getArg(Arg: 0),
399 TheCall->getDirectCallee()->getName(), false,
400 CallKind};
401 }
402 return std::nullopt;
403}
404
405/// Determine whether Init appears to be an initializing an iterator.
406///
407/// If it is, returns the object whose begin() or end() method is called, and
408/// the output parameter isArrow is set to indicate whether the initialization
409/// is called via . or ->.
410static std::pair<const Expr *, IteratorCallKind>
411getContainerFromBeginEndCall(const Expr *Init, bool IsBegin, bool *IsArrow,
412 bool IsReverse) {
413 // FIXME: Maybe allow declaration/initialization outside of the for loop.
414
415 std::optional<ContainerCall> Call = getContainerExpr(Call: Init);
416 if (!Call)
417 return {};
418
419 *IsArrow = Call->IsArrow;
420 if (!Call->Name.consume_back(Suffix: IsBegin ? "begin" : "end"))
421 return {};
422 if (IsReverse && !Call->Name.consume_back(Suffix: "r"))
423 return {};
424 if (!Call->Name.empty() && !Call->Name.equals(RHS: "c"))
425 return {};
426 return std::make_pair(x&: Call->Container, y&: Call->CallKind);
427}
428
429/// Determines the container whose begin() and end() functions are called
430/// for an iterator-based loop.
431///
432/// BeginExpr must be a member call to a function named "begin()", and EndExpr
433/// must be a member.
434static const Expr *findContainer(ASTContext *Context, const Expr *BeginExpr,
435 const Expr *EndExpr,
436 bool *ContainerNeedsDereference,
437 bool IsReverse) {
438 // Now that we know the loop variable and test expression, make sure they are
439 // valid.
440 bool BeginIsArrow = false;
441 bool EndIsArrow = false;
442 auto [BeginContainerExpr, BeginCallKind] = getContainerFromBeginEndCall(
443 Init: BeginExpr, /*IsBegin=*/true, IsArrow: &BeginIsArrow, IsReverse);
444 if (!BeginContainerExpr)
445 return nullptr;
446
447 auto [EndContainerExpr, EndCallKind] = getContainerFromBeginEndCall(
448 Init: EndExpr, /*IsBegin=*/false, IsArrow: &EndIsArrow, IsReverse);
449 if (BeginCallKind != EndCallKind)
450 return nullptr;
451
452 // Disallow loops that try evil things like this (note the dot and arrow):
453 // for (IteratorType It = Obj.begin(), E = Obj->end(); It != E; ++It) { }
454 if (!EndContainerExpr || BeginIsArrow != EndIsArrow ||
455 !areSameExpr(Context, First: EndContainerExpr, Second: BeginContainerExpr))
456 return nullptr;
457
458 *ContainerNeedsDereference = BeginIsArrow;
459 return BeginContainerExpr;
460}
461
462/// Obtain the original source code text from a SourceRange.
463static StringRef getStringFromRange(SourceManager &SourceMgr,
464 const LangOptions &LangOpts,
465 SourceRange Range) {
466 if (SourceMgr.getFileID(SpellingLoc: Range.getBegin()) !=
467 SourceMgr.getFileID(SpellingLoc: Range.getEnd())) {
468 return {}; // Empty string.
469 }
470
471 return Lexer::getSourceText(Range: CharSourceRange(Range, true), SM: SourceMgr,
472 LangOpts);
473}
474
475/// If the given expression is actually a DeclRefExpr or a MemberExpr,
476/// find and return the underlying ValueDecl; otherwise, return NULL.
477static const ValueDecl *getReferencedVariable(const Expr *E) {
478 if (const DeclRefExpr *DRE = getDeclRef(E))
479 return dyn_cast<VarDecl>(Val: DRE->getDecl());
480 if (const auto *Mem = dyn_cast<MemberExpr>(Val: E->IgnoreParenImpCasts()))
481 return dyn_cast<FieldDecl>(Val: Mem->getMemberDecl());
482 return nullptr;
483}
484
485/// Returns true when the given expression is a member expression
486/// whose base is `this` (implicitly or not).
487static bool isDirectMemberExpr(const Expr *E) {
488 if (const auto *Member = dyn_cast<MemberExpr>(Val: E->IgnoreParenImpCasts()))
489 return isa<CXXThisExpr>(Val: Member->getBase()->IgnoreParenImpCasts());
490 return false;
491}
492
493/// Given an expression that represents an usage of an element from the
494/// containter that we are iterating over, returns false when it can be
495/// guaranteed this element cannot be modified as a result of this usage.
496static bool canBeModified(ASTContext *Context, const Expr *E) {
497 if (E->getType().isConstQualified())
498 return false;
499 auto Parents = Context->getParents(Node: *E);
500 if (Parents.size() != 1)
501 return true;
502 if (const auto *Cast = Parents[0].get<ImplicitCastExpr>()) {
503 if ((Cast->getCastKind() == CK_NoOp &&
504 Context->hasSameType(Cast->getType(), E->getType().withConst())) ||
505 (Cast->getCastKind() == CK_LValueToRValue &&
506 !Cast->getType().isNull() && Cast->getType()->isFundamentalType()))
507 return false;
508 }
509 // FIXME: Make this function more generic.
510 return true;
511}
512
513/// Returns true when it can be guaranteed that the elements of the
514/// container are not being modified.
515static bool usagesAreConst(ASTContext *Context, const UsageResult &Usages) {
516 for (const Usage &U : Usages) {
517 // Lambda captures are just redeclarations (VarDecl) of the same variable,
518 // not expressions. If we want to know if a variable that is captured by
519 // reference can be modified in an usage inside the lambda's body, we need
520 // to find the expression corresponding to that particular usage, later in
521 // this loop.
522 if (U.Kind != Usage::UK_CaptureByCopy && U.Kind != Usage::UK_CaptureByRef &&
523 canBeModified(Context, E: U.Expression))
524 return false;
525 }
526 return true;
527}
528
529/// Returns true if the elements of the container are never accessed
530/// by reference.
531static bool usagesReturnRValues(const UsageResult &Usages) {
532 for (const auto &U : Usages) {
533 if (U.Expression && !U.Expression->isPRValue())
534 return false;
535 }
536 return true;
537}
538
539/// Returns true if the container is const-qualified.
540static bool containerIsConst(const Expr *ContainerExpr, bool Dereference) {
541 if (const auto *VDec = getReferencedVariable(E: ContainerExpr)) {
542 QualType CType = VDec->getType();
543 if (Dereference) {
544 if (!CType->isPointerType())
545 return false;
546 CType = CType->getPointeeType();
547 }
548 // If VDec is a reference to a container, Dereference is false,
549 // but we still need to check the const-ness of the underlying container
550 // type.
551 CType = CType.getNonReferenceType();
552 return CType.isConstQualified();
553 }
554 return false;
555}
556
557LoopConvertCheck::LoopConvertCheck(StringRef Name, ClangTidyContext *Context)
558 : ClangTidyCheck(Name, Context), TUInfo(new TUTrackingInfo),
559 MaxCopySize(Options.get(LocalName: "MaxCopySize", Default: 16ULL)),
560 MinConfidence(Options.get(LocalName: "MinConfidence", Default: Confidence::CL_Reasonable)),
561 NamingStyle(Options.get(LocalName: "NamingStyle", Default: VariableNamer::NS_CamelCase)),
562 Inserter(Options.getLocalOrGlobal(LocalName: "IncludeStyle",
563 Default: utils::IncludeSorter::IS_LLVM),
564 areDiagsSelfContained()),
565 UseCxx20IfAvailable(Options.get(LocalName: "UseCxx20ReverseRanges", Default: true)),
566 ReverseFunction(Options.get(LocalName: "MakeReverseRangeFunction", Default: "")),
567 ReverseHeader(Options.get(LocalName: "MakeReverseRangeHeader", Default: "")) {
568
569 if (ReverseFunction.empty() && !ReverseHeader.empty()) {
570 configurationDiag(
571 Description: "modernize-loop-convert: 'MakeReverseRangeHeader' is set but "
572 "'MakeReverseRangeFunction' is not, disabling reverse loop "
573 "transformation");
574 UseReverseRanges = false;
575 } else if (ReverseFunction.empty()) {
576 UseReverseRanges = UseCxx20IfAvailable && getLangOpts().CPlusPlus20;
577 } else {
578 UseReverseRanges = true;
579 }
580}
581
582void LoopConvertCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
583 Options.store(Options&: Opts, LocalName: "MaxCopySize", Value: MaxCopySize);
584 Options.store(Options&: Opts, LocalName: "MinConfidence", Value: MinConfidence);
585 Options.store(Options&: Opts, LocalName: "NamingStyle", Value: NamingStyle);
586 Options.store(Options&: Opts, LocalName: "IncludeStyle", Value: Inserter.getStyle());
587 Options.store(Options&: Opts, LocalName: "UseCxx20ReverseRanges", Value: UseCxx20IfAvailable);
588 Options.store(Options&: Opts, LocalName: "MakeReverseRangeFunction", Value: ReverseFunction);
589 Options.store(Options&: Opts, LocalName: "MakeReverseRangeHeader", Value: ReverseHeader);
590}
591
592void LoopConvertCheck::registerPPCallbacks(const SourceManager &SM,
593 Preprocessor *PP,
594 Preprocessor *ModuleExpanderPP) {
595 Inserter.registerPreprocessor(PP);
596}
597
598void LoopConvertCheck::registerMatchers(MatchFinder *Finder) {
599 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makeArrayLoopMatcher()), Action: this);
600 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makeIteratorLoopMatcher(IsReverse: false)), Action: this);
601 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makePseudoArrayLoopMatcher()), Action: this);
602 if (UseReverseRanges)
603 Finder->addMatcher(NodeMatch: traverse(TK: TK_AsIs, InnerMatcher: makeIteratorLoopMatcher(IsReverse: true)), Action: this);
604}
605
606/// Given the range of a single declaration, such as:
607/// \code
608/// unsigned &ThisIsADeclarationThatCanSpanSeveralLinesOfCode =
609/// InitializationValues[I];
610/// next_instruction;
611/// \endcode
612/// Finds the range that has to be erased to remove this declaration without
613/// leaving empty lines, by extending the range until the beginning of the
614/// next instruction.
615///
616/// We need to delete a potential newline after the deleted alias, as
617/// clang-format will leave empty lines untouched. For all other formatting we
618/// rely on clang-format to fix it.
619void LoopConvertCheck::getAliasRange(SourceManager &SM, SourceRange &Range) {
620 bool Invalid = false;
621 const char *TextAfter =
622 SM.getCharacterData(SL: Range.getEnd().getLocWithOffset(Offset: 1), Invalid: &Invalid);
623 if (Invalid)
624 return;
625 unsigned Offset = std::strspn(s: TextAfter, accept: " \t\r\n");
626 Range =
627 SourceRange(Range.getBegin(), Range.getEnd().getLocWithOffset(Offset));
628}
629
630/// Computes the changes needed to convert a given for loop, and
631/// applies them.
632void LoopConvertCheck::doConversion(
633 ASTContext *Context, const VarDecl *IndexVar,
634 const ValueDecl *MaybeContainer, const UsageResult &Usages,
635 const DeclStmt *AliasDecl, bool AliasUseRequired, bool AliasFromForInit,
636 const ForStmt *Loop, RangeDescriptor Descriptor) {
637 std::string VarNameOrStructuredBinding;
638 bool VarNameFromAlias = (Usages.size() == 1) && AliasDecl;
639 bool AliasVarIsRef = false;
640 bool CanCopy = true;
641 std::vector<FixItHint> FixIts;
642 if (VarNameFromAlias) {
643 const auto *AliasVar = cast<VarDecl>(Val: AliasDecl->getSingleDecl());
644
645 // Handle structured bindings
646 if (const auto *AliasDecompositionDecl =
647 dyn_cast<DecompositionDecl>(Val: AliasDecl->getSingleDecl())) {
648 VarNameOrStructuredBinding = "[";
649
650 assert(!AliasDecompositionDecl->bindings().empty() && "No bindings");
651 for (const BindingDecl *Binding : AliasDecompositionDecl->bindings()) {
652 VarNameOrStructuredBinding += Binding->getName().str() + ", ";
653 }
654
655 VarNameOrStructuredBinding.erase(pos: VarNameOrStructuredBinding.size() - 2,
656 n: 2);
657 VarNameOrStructuredBinding += "]";
658 } else {
659 VarNameOrStructuredBinding = AliasVar->getName().str();
660
661 // Use the type of the alias if it's not the same
662 QualType AliasVarType = AliasVar->getType();
663 assert(!AliasVarType.isNull() && "Type in VarDecl is null");
664 if (AliasVarType->isReferenceType()) {
665 AliasVarType = AliasVarType.getNonReferenceType();
666 AliasVarIsRef = true;
667 }
668 if (Descriptor.ElemType.isNull() ||
669 !Context->hasSameUnqualifiedType(T1: AliasVarType, T2: Descriptor.ElemType))
670 Descriptor.ElemType = AliasVarType;
671 }
672
673 // We keep along the entire DeclStmt to keep the correct range here.
674 SourceRange ReplaceRange = AliasDecl->getSourceRange();
675
676 std::string ReplacementText;
677 if (AliasUseRequired) {
678 ReplacementText = VarNameOrStructuredBinding;
679 } else if (AliasFromForInit) {
680 // FIXME: Clang includes the location of the ';' but only for DeclStmt's
681 // in a for loop's init clause. Need to put this ';' back while removing
682 // the declaration of the alias variable. This is probably a bug.
683 ReplacementText = ";";
684 } else {
685 // Avoid leaving empty lines or trailing whitespaces.
686 getAliasRange(SM&: Context->getSourceManager(), Range&: ReplaceRange);
687 }
688
689 FixIts.push_back(x: FixItHint::CreateReplacement(
690 RemoveRange: CharSourceRange::getTokenRange(R: ReplaceRange), Code: ReplacementText));
691 // No further replacements are made to the loop, since the iterator or index
692 // was used exactly once - in the initialization of AliasVar.
693 } else {
694 VariableNamer Namer(&TUInfo->getGeneratedDecls(),
695 &TUInfo->getParentFinder().getStmtToParentStmtMap(),
696 Loop, IndexVar, MaybeContainer, Context, NamingStyle);
697 VarNameOrStructuredBinding = Namer.createIndexName();
698 // First, replace all usages of the array subscript expression with our new
699 // variable.
700 for (const auto &Usage : Usages) {
701 std::string ReplaceText;
702 SourceRange Range = Usage.Range;
703 if (Usage.Expression) {
704 // If this is an access to a member through the arrow operator, after
705 // the replacement it must be accessed through the '.' operator.
706 ReplaceText = Usage.Kind == Usage::UK_MemberThroughArrow
707 ? VarNameOrStructuredBinding + "."
708 : VarNameOrStructuredBinding;
709 const DynTypedNodeList Parents = Context->getParents(Node: *Usage.Expression);
710 if (Parents.size() == 1) {
711 if (const auto *Paren = Parents[0].get<ParenExpr>()) {
712 // Usage.Expression will be replaced with the new index variable,
713 // and parenthesis around a simple DeclRefExpr can always be
714 // removed except in case of a `sizeof` operator call.
715 const DynTypedNodeList GrandParents = Context->getParents(Node: *Paren);
716 if (GrandParents.size() != 1 ||
717 GrandParents[0].get<UnaryExprOrTypeTraitExpr>() == nullptr) {
718 Range = Paren->getSourceRange();
719 }
720 } else if (const auto *UOP = Parents[0].get<UnaryOperator>()) {
721 // If we are taking the address of the loop variable, then we must
722 // not use a copy, as it would mean taking the address of the loop's
723 // local index instead.
724 // FIXME: This won't catch cases where the address is taken outside
725 // of the loop's body (for instance, in a function that got the
726 // loop's index as a const reference parameter), or where we take
727 // the address of a member (like "&Arr[i].A.B.C").
728 if (UOP->getOpcode() == UO_AddrOf)
729 CanCopy = false;
730 }
731 }
732 } else {
733 // The Usage expression is only null in case of lambda captures (which
734 // are VarDecl). If the index is captured by value, add '&' to capture
735 // by reference instead.
736 ReplaceText = Usage.Kind == Usage::UK_CaptureByCopy
737 ? "&" + VarNameOrStructuredBinding
738 : VarNameOrStructuredBinding;
739 }
740 TUInfo->getReplacedVars().insert(KV: std::make_pair(x&: Loop, y&: IndexVar));
741 FixIts.push_back(x: FixItHint::CreateReplacement(
742 RemoveRange: CharSourceRange::getTokenRange(R: Range), Code: ReplaceText));
743 }
744 }
745
746 // Now, we need to construct the new range expression.
747 SourceRange ParenRange(Loop->getLParenLoc(), Loop->getRParenLoc());
748
749 QualType Type = Context->getAutoDeductType();
750 if (!Descriptor.ElemType.isNull() && Descriptor.ElemType->isFundamentalType())
751 Type = Descriptor.ElemType.getUnqualifiedType();
752 Type = Type.getDesugaredType(Context: *Context);
753
754 // If the new variable name is from the aliased variable, then the reference
755 // type for the new variable should only be used if the aliased variable was
756 // declared as a reference.
757 bool IsCheapToCopy =
758 !Descriptor.ElemType.isNull() &&
759 Descriptor.ElemType.isTriviallyCopyableType(*Context) &&
760 !Descriptor.ElemType->isDependentSizedArrayType() &&
761 // TypeInfo::Width is in bits.
762 Context->getTypeInfo(Descriptor.ElemType).Width <= 8 * MaxCopySize;
763 bool UseCopy = CanCopy && ((VarNameFromAlias && !AliasVarIsRef) ||
764 (Descriptor.DerefByConstRef && IsCheapToCopy));
765
766 if (!UseCopy) {
767 if (Descriptor.DerefByConstRef) {
768 Type = Context->getLValueReferenceType(T: Context->getConstType(T: Type));
769 } else if (Descriptor.DerefByValue) {
770 if (!IsCheapToCopy)
771 Type = Context->getRValueReferenceType(T: Type);
772 } else {
773 Type = Context->getLValueReferenceType(T: Type);
774 }
775 }
776
777 SmallString<128> Range;
778 llvm::raw_svector_ostream Output(Range);
779 Output << '(';
780 Type.print(OS&: Output, Policy: getLangOpts());
781 Output << ' ' << VarNameOrStructuredBinding << " : ";
782 if (Descriptor.NeedsReverseCall)
783 Output << getReverseFunction() << '(';
784 if (Descriptor.ContainerNeedsDereference)
785 Output << '*';
786 Output << Descriptor.ContainerString;
787 if (Descriptor.NeedsReverseCall)
788 Output << "))";
789 else
790 Output << ')';
791 FixIts.push_back(x: FixItHint::CreateReplacement(
792 RemoveRange: CharSourceRange::getTokenRange(R: ParenRange), Code: Range));
793
794 if (Descriptor.NeedsReverseCall && !getReverseHeader().empty()) {
795 if (std::optional<FixItHint> Insertion = Inserter.createIncludeInsertion(
796 FileID: Context->getSourceManager().getFileID(SpellingLoc: Loop->getBeginLoc()),
797 Header: getReverseHeader()))
798 FixIts.push_back(x: *Insertion);
799 }
800 diag(Loc: Loop->getForLoc(), Description: "use range-based for loop instead") << FixIts;
801 TUInfo->getGeneratedDecls().insert(
802 KV: make_pair(x&: Loop, y&: VarNameOrStructuredBinding));
803}
804
805/// Returns a string which refers to the container iterated over.
806StringRef LoopConvertCheck::getContainerString(ASTContext *Context,
807 const ForStmt *Loop,
808 const Expr *ContainerExpr) {
809 StringRef ContainerString;
810 ContainerExpr = ContainerExpr->IgnoreParenImpCasts();
811 if (isa<CXXThisExpr>(Val: ContainerExpr)) {
812 ContainerString = "this";
813 } else {
814 // For CXXOperatorCallExpr such as vector_ptr->size() we want the class
815 // object vector_ptr, but for vector[2] we need the whole expression.
816 if (const auto *E = dyn_cast<CXXOperatorCallExpr>(Val: ContainerExpr))
817 if (E->getOperator() != OO_Subscript)
818 ContainerExpr = E->getArg(0);
819 ContainerString =
820 getStringFromRange(Context->getSourceManager(), Context->getLangOpts(),
821 ContainerExpr->getSourceRange());
822 }
823
824 return ContainerString;
825}
826
827/// Determines what kind of 'auto' must be used after converting a for
828/// loop that iterates over an array or pseudoarray.
829void LoopConvertCheck::getArrayLoopQualifiers(ASTContext *Context,
830 const BoundNodes &Nodes,
831 const Expr *ContainerExpr,
832 const UsageResult &Usages,
833 RangeDescriptor &Descriptor) {
834 // On arrays and pseudoarrays, we must figure out the qualifiers from the
835 // usages.
836 if (usagesAreConst(Context, Usages) ||
837 containerIsConst(ContainerExpr, Dereference: Descriptor.ContainerNeedsDereference)) {
838 Descriptor.DerefByConstRef = true;
839 }
840 if (usagesReturnRValues(Usages)) {
841 // If the index usages (dereference, subscript, at, ...) return rvalues,
842 // then we should not use a reference, because we need to keep the code
843 // correct if it mutates the returned objects.
844 Descriptor.DerefByValue = true;
845 }
846 // Try to find the type of the elements on the container, to check if
847 // they are trivially copyable.
848 for (const Usage &U : Usages) {
849 if (!U.Expression || U.Expression->getType().isNull())
850 continue;
851 QualType Type = U.Expression->getType().getCanonicalType();
852 if (U.Kind == Usage::UK_MemberThroughArrow) {
853 if (!Type->isPointerType()) {
854 continue;
855 }
856 Type = Type->getPointeeType();
857 }
858 Descriptor.ElemType = Type;
859 }
860}
861
862/// Determines what kind of 'auto' must be used after converting an
863/// iterator based for loop.
864void LoopConvertCheck::getIteratorLoopQualifiers(ASTContext *Context,
865 const BoundNodes &Nodes,
866 RangeDescriptor &Descriptor) {
867 // The matchers for iterator loops provide bound nodes to obtain this
868 // information.
869 const auto *InitVar = Nodes.getNodeAs<VarDecl>(ID: InitVarName);
870 QualType CanonicalInitVarType = InitVar->getType().getCanonicalType();
871 const auto *DerefByValueType =
872 Nodes.getNodeAs<QualType>(ID: DerefByValueResultName);
873 Descriptor.DerefByValue = DerefByValueType;
874
875 if (Descriptor.DerefByValue) {
876 // If the dereference operator returns by value then test for the
877 // canonical const qualification of the init variable type.
878 Descriptor.DerefByConstRef = CanonicalInitVarType.isConstQualified();
879 Descriptor.ElemType = *DerefByValueType;
880 } else {
881 if (const auto *DerefType =
882 Nodes.getNodeAs<QualType>(ID: DerefByRefResultName)) {
883 // A node will only be bound with DerefByRefResultName if we're dealing
884 // with a user-defined iterator type. Test the const qualification of
885 // the reference type.
886 auto ValueType = DerefType->getNonReferenceType();
887
888 Descriptor.DerefByConstRef = ValueType.isConstQualified();
889 Descriptor.ElemType = ValueType;
890 } else {
891 // By nature of the matcher this case is triggered only for built-in
892 // iterator types (i.e. pointers).
893 assert(isa<PointerType>(CanonicalInitVarType) &&
894 "Non-class iterator type is not a pointer type");
895
896 // We test for const qualification of the pointed-at type.
897 Descriptor.DerefByConstRef =
898 CanonicalInitVarType->getPointeeType().isConstQualified();
899 Descriptor.ElemType = CanonicalInitVarType->getPointeeType();
900 }
901 }
902}
903
904/// Determines the parameters needed to build the range replacement.
905void LoopConvertCheck::determineRangeDescriptor(
906 ASTContext *Context, const BoundNodes &Nodes, const ForStmt *Loop,
907 LoopFixerKind FixerKind, const Expr *ContainerExpr,
908 const UsageResult &Usages, RangeDescriptor &Descriptor) {
909 Descriptor.ContainerString =
910 std::string(getContainerString(Context, Loop, ContainerExpr));
911 Descriptor.NeedsReverseCall = (FixerKind == LFK_ReverseIterator);
912
913 if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator)
914 getIteratorLoopQualifiers(Context, Nodes, Descriptor);
915 else
916 getArrayLoopQualifiers(Context, Nodes, ContainerExpr, Usages, Descriptor);
917}
918
919/// Check some of the conditions that must be met for the loop to be
920/// convertible.
921bool LoopConvertCheck::isConvertible(ASTContext *Context,
922 const ast_matchers::BoundNodes &Nodes,
923 const ForStmt *Loop,
924 LoopFixerKind FixerKind) {
925 // In self contained diagnosics mode we don't want dependancies on other
926 // loops, otherwise, If we already modified the range of this for loop, don't
927 // do any further updates on this iteration.
928 if (areDiagsSelfContained())
929 TUInfo = std::make_unique<TUTrackingInfo>();
930 else if (TUInfo->getReplacedVars().count(Val: Loop))
931 return false;
932
933 // Check that we have exactly one index variable and at most one end variable.
934 const auto *InitVar = Nodes.getNodeAs<VarDecl>(ID: InitVarName);
935
936 // FIXME: Try to put most of this logic inside a matcher.
937 if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator) {
938 QualType InitVarType = InitVar->getType();
939 QualType CanonicalInitVarType = InitVarType.getCanonicalType();
940
941 const auto *BeginCall = Nodes.getNodeAs<CallExpr>(ID: BeginCallName);
942 assert(BeginCall && "Bad Callback. No begin call expression");
943 QualType CanonicalBeginType =
944 BeginCall->getDirectCallee()->getReturnType().getCanonicalType();
945 if (CanonicalBeginType->isPointerType() &&
946 CanonicalInitVarType->isPointerType()) {
947 // If the initializer and the variable are both pointers check if the
948 // un-qualified pointee types match, otherwise we don't use auto.
949 return Context->hasSameUnqualifiedType(
950 T1: CanonicalBeginType->getPointeeType(),
951 T2: CanonicalInitVarType->getPointeeType());
952 }
953
954 if (CanonicalBeginType->isBuiltinType() ||
955 CanonicalInitVarType->isBuiltinType())
956 return false;
957
958 } else if (FixerKind == LFK_PseudoArray) {
959 if (const auto *EndCall = Nodes.getNodeAs<CXXMemberCallExpr>(ID: EndCallName)) {
960 // This call is required to obtain the container.
961 if (!isa<MemberExpr>(EndCall->getCallee()))
962 return false;
963 }
964 return Nodes.getNodeAs<CallExpr>(ID: EndCallName) != nullptr;
965 }
966 return true;
967}
968
969void LoopConvertCheck::check(const MatchFinder::MatchResult &Result) {
970 const BoundNodes &Nodes = Result.Nodes;
971 Confidence ConfidenceLevel(Confidence::CL_Safe);
972 ASTContext *Context = Result.Context;
973
974 const ForStmt *Loop = nullptr;
975 LoopFixerKind FixerKind{};
976 RangeDescriptor Descriptor;
977
978 if ((Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNameArray))) {
979 FixerKind = LFK_Array;
980 } else if ((Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNameIterator))) {
981 FixerKind = LFK_Iterator;
982 } else if ((Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNameReverseIterator))) {
983 FixerKind = LFK_ReverseIterator;
984 } else {
985 Loop = Nodes.getNodeAs<ForStmt>(ID: LoopNamePseudoArray);
986 assert(Loop && "Bad Callback. No for statement");
987 FixerKind = LFK_PseudoArray;
988 }
989
990 if (!isConvertible(Context, Nodes, Loop, FixerKind))
991 return;
992
993 const auto *LoopVar = Nodes.getNodeAs<VarDecl>(ID: InitVarName);
994 const auto *EndVar = Nodes.getNodeAs<VarDecl>(ID: EndVarName);
995
996 // If the loop calls end()/size() after each iteration, lower our confidence
997 // level.
998 if (FixerKind != LFK_Array && !EndVar)
999 ConfidenceLevel.lowerTo(Level: Confidence::CL_Reasonable);
1000
1001 // If the end comparison isn't a variable, we can try to work with the
1002 // expression the loop variable is being tested against instead.
1003 const auto *EndCall = Nodes.getNodeAs<Expr>(ID: EndCallName);
1004 const auto *BoundExpr = Nodes.getNodeAs<Expr>(ID: ConditionBoundName);
1005
1006 // Find container expression of iterators and pseudoarrays, and determine if
1007 // this expression needs to be dereferenced to obtain the container.
1008 // With array loops, the container is often discovered during the
1009 // ForLoopIndexUseVisitor traversal.
1010 const Expr *ContainerExpr = nullptr;
1011 if (FixerKind == LFK_Iterator || FixerKind == LFK_ReverseIterator) {
1012 ContainerExpr = findContainer(
1013 Context, BeginExpr: LoopVar->getInit(), EndExpr: EndVar ? EndVar->getInit() : EndCall,
1014 ContainerNeedsDereference: &Descriptor.ContainerNeedsDereference,
1015 /*IsReverse=*/FixerKind == LFK_ReverseIterator);
1016 } else if (FixerKind == LFK_PseudoArray) {
1017 std::optional<ContainerCall> Call = getContainerExpr(Call: EndCall);
1018 if (Call) {
1019 ContainerExpr = Call->Container;
1020 Descriptor.ContainerNeedsDereference = Call->IsArrow;
1021 }
1022 }
1023
1024 // We must know the container or an array length bound.
1025 if (!ContainerExpr && !BoundExpr)
1026 return;
1027
1028 ForLoopIndexUseVisitor Finder(Context, LoopVar, EndVar, ContainerExpr,
1029 BoundExpr,
1030 Descriptor.ContainerNeedsDereference);
1031
1032 // Find expressions and variables on which the container depends.
1033 if (ContainerExpr) {
1034 ComponentFinderASTVisitor ComponentFinder;
1035 ComponentFinder.findExprComponents(SourceExpr: ContainerExpr->IgnoreParenImpCasts());
1036 Finder.addComponents(Components: ComponentFinder.getComponents());
1037 }
1038
1039 // Find usages of the loop index. If they are not used in a convertible way,
1040 // stop here.
1041 if (!Finder.findAndVerifyUsages(Body: Loop->getBody()))
1042 return;
1043 ConfidenceLevel.lowerTo(Level: Finder.getConfidenceLevel());
1044
1045 // Obtain the container expression, if we don't have it yet.
1046 if (FixerKind == LFK_Array) {
1047 ContainerExpr = Finder.getContainerIndexed()->IgnoreParenImpCasts();
1048
1049 // Very few loops are over expressions that generate arrays rather than
1050 // array variables. Consider loops over arrays that aren't just represented
1051 // by a variable to be risky conversions.
1052 if (!getReferencedVariable(E: ContainerExpr) &&
1053 !isDirectMemberExpr(E: ContainerExpr))
1054 ConfidenceLevel.lowerTo(Level: Confidence::CL_Risky);
1055 }
1056
1057 // Find out which qualifiers we have to use in the loop range.
1058 TraversalKindScope RAII(*Context, TK_AsIs);
1059 const UsageResult &Usages = Finder.getUsages();
1060 determineRangeDescriptor(Context, Nodes, Loop, FixerKind, ContainerExpr,
1061 Usages, Descriptor);
1062
1063 // Ensure that we do not try to move an expression dependent on a local
1064 // variable declared inside the loop outside of it.
1065 // FIXME: Determine when the external dependency isn't an expression converted
1066 // by another loop.
1067 TUInfo->getParentFinder().gatherAncestors(Ctx&: *Context);
1068 DependencyFinderASTVisitor DependencyFinder(
1069 &TUInfo->getParentFinder().getStmtToParentStmtMap(),
1070 &TUInfo->getParentFinder().getDeclToParentStmtMap(),
1071 &TUInfo->getReplacedVars(), Loop);
1072
1073 if (DependencyFinder.dependsOnInsideVariable(ContainerExpr) ||
1074 Descriptor.ContainerString.empty() || Usages.empty() ||
1075 ConfidenceLevel.getLevel() < MinConfidence)
1076 return;
1077
1078 doConversion(Context, IndexVar: LoopVar, MaybeContainer: getReferencedVariable(E: ContainerExpr), Usages,
1079 AliasDecl: Finder.getAliasDecl(), AliasUseRequired: Finder.aliasUseRequired(),
1080 AliasFromForInit: Finder.aliasFromForInit(), Loop, Descriptor);
1081}
1082
1083llvm::StringRef LoopConvertCheck::getReverseFunction() const {
1084 if (!ReverseFunction.empty())
1085 return ReverseFunction;
1086 if (UseReverseRanges)
1087 return "std::ranges::reverse_view";
1088 return "";
1089}
1090
1091llvm::StringRef LoopConvertCheck::getReverseHeader() const {
1092 if (!ReverseHeader.empty())
1093 return ReverseHeader;
1094 if (UseReverseRanges && ReverseFunction.empty()) {
1095 return "<ranges>";
1096 }
1097 return "";
1098}
1099
1100} // namespace modernize
1101} // namespace clang::tidy
1102

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