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 | |
27 | using namespace clang::ast_matchers; |
28 | using namespace llvm; |
29 | |
30 | namespace clang::tidy { |
31 | |
32 | template <> 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 | |
43 | template <> 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 | |
56 | namespace modernize { |
57 | |
58 | static const char LoopNameArray[] = "forLoopArray"; |
59 | static const char LoopNameIterator[] = "forLoopIterator"; |
60 | static const char LoopNameReverseIterator[] = "forLoopReverseIterator"; |
61 | static const char LoopNamePseudoArray[] = "forLoopPseudoArray"; |
62 | static const char ConditionBoundName[] = "conditionBound"; |
63 | static const char InitVarName[] = "initVar"; |
64 | static const char BeginCallName[] = "beginCall"; |
65 | static const char EndCallName[] = "endCall"; |
66 | static const char EndVarName[] = "endVar"; |
67 | static const char DerefByValueResultName[] = "derefByValueResult"; |
68 | static const char DerefByRefResultName[] = "derefByRefResult"; |
69 | static const llvm::StringSet<> MemberNames{"begin", "cbegin", "rbegin", |
70 | "crbegin", "end", "cend", |
71 | "rend", "crend", "size"}; |
72 | static const llvm::StringSet<> ADLNames{"begin", "cbegin", "rbegin", |
73 | "crbegin", "end", "cend", |
74 | "rend", "crend", "size"}; |
75 | static 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 | |
79 | static StatementMatcher integerComparisonMatcher() { |
80 | return expr(ignoringParenImpCasts( |
81 | InnerMatcher: declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName)))))); |
82 | } |
83 | |
84 | static DeclarationMatcher initToZeroMatcher() { |
85 | return varDecl( |
86 | hasInitializer(InnerMatcher: ignoringParenImpCasts(InnerMatcher: integerLiteral(equals(Value: 0))))) |
87 | .bind(ID: InitVarName); |
88 | } |
89 | |
90 | static StatementMatcher incrementVarMatcher() { |
91 | return declRefExpr(to(InnerMatcher: varDecl(equalsBoundNode(ID: InitVarName)))); |
92 | } |
93 | |
94 | static StatementMatcher |
95 | arrayConditionMatcher(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. |
117 | static 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. |
158 | static 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. |
270 | static 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 | |
334 | enum class IteratorCallKind { |
335 | ICK_Member, |
336 | ICK_ADL, |
337 | ICK_Std, |
338 | }; |
339 | |
340 | struct 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> |
355 | static 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 ->. |
408 | static std::pair<const Expr *, IteratorCallKind> |
409 | getContainerFromBeginEndCall(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. |
432 | static 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. |
461 | static 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. |
475 | static 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). |
485 | static 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. |
494 | static 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. |
513 | static 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. |
529 | static 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. |
538 | static 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 | |
555 | LoopConvertCheck::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 | |
580 | void 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 | |
590 | void LoopConvertCheck::registerPPCallbacks(const SourceManager &SM, |
591 | Preprocessor *PP, |
592 | Preprocessor *ModuleExpanderPP) { |
593 | Inserter.registerPreprocessor(PP); |
594 | } |
595 | |
596 | void 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. |
617 | void 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. |
630 | void 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. |
804 | StringRef 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. |
827 | void 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. |
862 | void 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. |
903 | void 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. |
919 | bool 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 | |
967 | void 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 | |
1081 | llvm::StringRef LoopConvertCheck::getReverseFunction() const { |
1082 | if (!ReverseFunction.empty()) |
1083 | return ReverseFunction; |
1084 | if (UseReverseRanges) |
1085 | return "std::ranges::reverse_view"; |
1086 | return ""; |
1087 | } |
1088 | |
1089 | llvm::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 |
Definitions
- OptionEnumMapping
- getEnumMapping
- OptionEnumMapping
- getEnumMapping
- LoopNameArray
- LoopNameIterator
- LoopNameReverseIterator
- LoopNamePseudoArray
- ConditionBoundName
- InitVarName
- BeginCallName
- EndCallName
- EndVarName
- DerefByValueResultName
- DerefByRefResultName
- MemberNames
- ADLNames
- StdNames
- integerComparisonMatcher
- initToZeroMatcher
- incrementVarMatcher
- arrayConditionMatcher
- makeArrayLoopMatcher
- makeIteratorLoopMatcher
- makePseudoArrayLoopMatcher
- IteratorCallKind
- ContainerCall
- getContainerExpr
- getContainerFromBeginEndCall
- findContainer
- getStringFromRange
- getReferencedVariable
- isDirectMemberExpr
- canBeModified
- usagesAreConst
- usagesReturnRValues
- containerIsConst
- LoopConvertCheck
- storeOptions
- registerPPCallbacks
- registerMatchers
- getAliasRange
- doConversion
- getContainerString
- getArrayLoopQualifiers
- getIteratorLoopQualifiers
- determineRangeDescriptor
- isConvertible
- check
- getReverseFunction
Improve your Profiling and Debugging skills
Find out more