UseTrailingReturnTypeCheck.cpp
18.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
//===--- UseTrailingReturnTypeCheck.cpp - clang-tidy-----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "UseTrailingReturnTypeCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Tooling/FixIt.h"
#include "llvm/ADT/StringExtras.h"
#include <cctype>
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace modernize {
namespace {
struct UnqualNameVisitor : public RecursiveASTVisitor<UnqualNameVisitor> {
public:
UnqualNameVisitor(const FunctionDecl &F) : F(F) {}
bool Collision = false;
bool shouldWalkTypesOfTypeLocs() const { return false; }
bool VisitUnqualName(StringRef UnqualName) {
// Check for collisions with function arguments.
for (ParmVarDecl *Param : F.parameters())
if (const IdentifierInfo *Ident = Param->getIdentifier())
if (Ident->getName() == UnqualName) {
Collision = true;
return true;
}
return false;
}
bool TraverseTypeLoc(TypeLoc TL, bool Elaborated = false) {
if (TL.isNull())
return true;
if (!Elaborated) {
switch (TL.getTypeLocClass()) {
case TypeLoc::Record:
if (VisitUnqualName(
TL.getAs<RecordTypeLoc>().getTypePtr()->getDecl()->getName()))
return false;
break;
case TypeLoc::Enum:
if (VisitUnqualName(
TL.getAs<EnumTypeLoc>().getTypePtr()->getDecl()->getName()))
return false;
break;
case TypeLoc::TemplateSpecialization:
if (VisitUnqualName(TL.getAs<TemplateSpecializationTypeLoc>()
.getTypePtr()
->getTemplateName()
.getAsTemplateDecl()
->getName()))
return false;
break;
case TypeLoc::Typedef:
if (VisitUnqualName(
TL.getAs<TypedefTypeLoc>().getTypePtr()->getDecl()->getName()))
return false;
break;
default:
break;
}
}
return RecursiveASTVisitor<UnqualNameVisitor>::TraverseTypeLoc(TL);
}
// Replace the base method in order to call ower own
// TraverseTypeLoc().
bool TraverseQualifiedTypeLoc(QualifiedTypeLoc TL) {
return TraverseTypeLoc(TL.getUnqualifiedLoc());
}
// Replace the base version to inform TraverseTypeLoc that the type is
// elaborated.
bool TraverseElaboratedTypeLoc(ElaboratedTypeLoc TL) {
if (TL.getQualifierLoc() &&
!TraverseNestedNameSpecifierLoc(TL.getQualifierLoc()))
return false;
return TraverseTypeLoc(TL.getNamedTypeLoc(), true);
}
bool VisitDeclRefExpr(DeclRefExpr *S) {
DeclarationName Name = S->getNameInfo().getName();
return S->getQualifierLoc() || !Name.isIdentifier() ||
!VisitUnqualName(Name.getAsIdentifierInfo()->getName());
}
private:
const FunctionDecl &F;
};
} // namespace
constexpr llvm::StringLiteral Message =
"use a trailing return type for this function";
static SourceLocation expandIfMacroId(SourceLocation Loc,
const SourceManager &SM) {
if (Loc.isMacroID())
Loc = expandIfMacroId(SM.getImmediateExpansionRange(Loc).getBegin(), SM);
assert(!Loc.isMacroID() &&
"SourceLocation must not be a macro ID after recursive expansion");
return Loc;
}
SourceLocation UseTrailingReturnTypeCheck::findTrailingReturnTypeSourceLocation(
const FunctionDecl &F, const FunctionTypeLoc &FTL, const ASTContext &Ctx,
const SourceManager &SM, const LangOptions &LangOpts) {
// We start with the location of the closing parenthesis.
SourceRange ExceptionSpecRange = F.getExceptionSpecSourceRange();
if (ExceptionSpecRange.isValid())
return Lexer::getLocForEndOfToken(ExceptionSpecRange.getEnd(), 0, SM,
LangOpts);
// If the function argument list ends inside of a macro, it is dangerous to
// start lexing from here - bail out.
SourceLocation ClosingParen = FTL.getRParenLoc();
if (ClosingParen.isMacroID())
return {};
SourceLocation Result =
Lexer::getLocForEndOfToken(ClosingParen, 0, SM, LangOpts);
// Skip subsequent CV and ref qualifiers.
std::pair<FileID, unsigned> Loc = SM.getDecomposedLoc(Result);
StringRef File = SM.getBufferData(Loc.first);
const char *TokenBegin = File.data() + Loc.second;
Lexer Lexer(SM.getLocForStartOfFile(Loc.first), LangOpts, File.begin(),
TokenBegin, File.end());
Token T;
while (!Lexer.LexFromRawLexer(T)) {
if (T.is(tok::raw_identifier)) {
IdentifierInfo &Info = Ctx.Idents.get(
StringRef(SM.getCharacterData(T.getLocation()), T.getLength()));
T.setIdentifierInfo(&Info);
T.setKind(Info.getTokenID());
}
if (T.isOneOf(tok::amp, tok::ampamp, tok::kw_const, tok::kw_volatile,
tok::kw_restrict)) {
Result = T.getEndLoc();
continue;
}
break;
}
return Result;
}
static bool IsCVR(Token T) {
return T.isOneOf(tok::kw_const, tok::kw_volatile, tok::kw_restrict);
}
static bool IsSpecifier(Token T) {
return T.isOneOf(tok::kw_constexpr, tok::kw_inline, tok::kw_extern,
tok::kw_static, tok::kw_friend, tok::kw_virtual);
}
static llvm::Optional<ClassifiedToken>
classifyToken(const FunctionDecl &F, Preprocessor &PP, Token Tok) {
ClassifiedToken CT;
CT.T = Tok;
CT.isQualifier = true;
CT.isSpecifier = true;
bool ContainsQualifiers = false;
bool ContainsSpecifiers = false;
bool ContainsSomethingElse = false;
Token End;
End.startToken();
End.setKind(tok::eof);
SmallVector<Token, 2> Stream{Tok, End};
// FIXME: do not report these token to Preprocessor.TokenWatcher.
PP.EnterTokenStream(Stream, false, /*IsReinject=*/false);
while (true) {
Token T;
PP.Lex(T);
if (T.is(tok::eof))
break;
bool Qual = IsCVR(T);
bool Spec = IsSpecifier(T);
CT.isQualifier &= Qual;
CT.isSpecifier &= Spec;
ContainsQualifiers |= Qual;
ContainsSpecifiers |= Spec;
ContainsSomethingElse |= !Qual && !Spec;
}
// If the Token/Macro contains more than one type of tokens, we would need
// to split the macro in order to move parts to the trailing return type.
if (ContainsQualifiers + ContainsSpecifiers + ContainsSomethingElse > 1)
return llvm::None;
return CT;
}
llvm::Optional<SmallVector<ClassifiedToken, 8>>
UseTrailingReturnTypeCheck::classifyTokensBeforeFunctionName(
const FunctionDecl &F, const ASTContext &Ctx, const SourceManager &SM,
const LangOptions &LangOpts) {
SourceLocation BeginF = expandIfMacroId(F.getBeginLoc(), SM);
SourceLocation BeginNameF = expandIfMacroId(F.getLocation(), SM);
// Create tokens for everything before the name of the function.
std::pair<FileID, unsigned> Loc = SM.getDecomposedLoc(BeginF);
StringRef File = SM.getBufferData(Loc.first);
const char *TokenBegin = File.data() + Loc.second;
Lexer Lexer(SM.getLocForStartOfFile(Loc.first), LangOpts, File.begin(),
TokenBegin, File.end());
Token T;
SmallVector<ClassifiedToken, 8> ClassifiedTokens;
while (!Lexer.LexFromRawLexer(T) &&
SM.isBeforeInTranslationUnit(T.getLocation(), BeginNameF)) {
if (T.is(tok::raw_identifier)) {
IdentifierInfo &Info = Ctx.Idents.get(
StringRef(SM.getCharacterData(T.getLocation()), T.getLength()));
if (Info.hasMacroDefinition()) {
const MacroInfo *MI = PP->getMacroInfo(&Info);
if (!MI || MI->isFunctionLike()) {
// Cannot handle function style macros.
diag(F.getLocation(), Message);
return llvm::None;
}
}
T.setIdentifierInfo(&Info);
T.setKind(Info.getTokenID());
}
if (llvm::Optional<ClassifiedToken> CT = classifyToken(F, *PP, T))
ClassifiedTokens.push_back(*CT);
else {
diag(F.getLocation(), Message);
return llvm::None;
}
}
return ClassifiedTokens;
}
static bool hasAnyNestedLocalQualifiers(QualType Type) {
bool Result = Type.hasLocalQualifiers();
if (Type->isPointerType())
Result = Result || hasAnyNestedLocalQualifiers(
Type->castAs<PointerType>()->getPointeeType());
if (Type->isReferenceType())
Result = Result || hasAnyNestedLocalQualifiers(
Type->castAs<ReferenceType>()->getPointeeType());
return Result;
}
SourceRange UseTrailingReturnTypeCheck::findReturnTypeAndCVSourceRange(
const FunctionDecl &F, const TypeLoc &ReturnLoc, const ASTContext &Ctx,
const SourceManager &SM, const LangOptions &LangOpts) {
// We start with the range of the return type and expand to neighboring
// qualifiers (const, volatile and restrict).
SourceRange ReturnTypeRange = F.getReturnTypeSourceRange();
if (ReturnTypeRange.isInvalid()) {
// Happens if e.g. clang cannot resolve all includes and the return type is
// unknown.
diag(F.getLocation(), Message);
return {};
}
// If the return type is a constrained 'auto' or 'decltype(auto)', we need to
// include the tokens after the concept. Unfortunately, the source range of an
// AutoTypeLoc, if it is constrained, does not include the 'auto' or
// 'decltype(auto)'. If the return type is a plain 'decltype(...)', the
// source range only contains the first 'decltype' token.
auto ATL = ReturnLoc.getAs<AutoTypeLoc>();
if ((ATL && (ATL.isConstrained() ||
ATL.getAutoKeyword() == AutoTypeKeyword::DecltypeAuto)) ||
ReturnLoc.getAs<DecltypeTypeLoc>()) {
SourceLocation End =
expandIfMacroId(ReturnLoc.getSourceRange().getEnd(), SM);
SourceLocation BeginNameF = expandIfMacroId(F.getLocation(), SM);
// Extend the ReturnTypeRange until the last token before the function
// name.
std::pair<FileID, unsigned> Loc = SM.getDecomposedLoc(End);
StringRef File = SM.getBufferData(Loc.first);
const char *TokenBegin = File.data() + Loc.second;
Lexer Lexer(SM.getLocForStartOfFile(Loc.first), LangOpts, File.begin(),
TokenBegin, File.end());
Token T;
SourceLocation LastTLoc = End;
while (!Lexer.LexFromRawLexer(T) &&
SM.isBeforeInTranslationUnit(T.getLocation(), BeginNameF)) {
LastTLoc = T.getLocation();
}
ReturnTypeRange.setEnd(LastTLoc);
}
// If the return type has no local qualifiers, it's source range is accurate.
if (!hasAnyNestedLocalQualifiers(F.getReturnType()))
return ReturnTypeRange;
// Include qualifiers to the left and right of the return type.
llvm::Optional<SmallVector<ClassifiedToken, 8>> MaybeTokens =
classifyTokensBeforeFunctionName(F, Ctx, SM, LangOpts);
if (!MaybeTokens)
return {};
const SmallVector<ClassifiedToken, 8> &Tokens = *MaybeTokens;
ReturnTypeRange.setBegin(expandIfMacroId(ReturnTypeRange.getBegin(), SM));
ReturnTypeRange.setEnd(expandIfMacroId(ReturnTypeRange.getEnd(), SM));
bool ExtendedLeft = false;
for (size_t I = 0; I < Tokens.size(); I++) {
// If we found the beginning of the return type, include left qualifiers.
if (!SM.isBeforeInTranslationUnit(Tokens[I].T.getLocation(),
ReturnTypeRange.getBegin()) &&
!ExtendedLeft) {
assert(I <= size_t(std::numeric_limits<int>::max()) &&
"Integer overflow detected");
for (int J = static_cast<int>(I) - 1; J >= 0 && Tokens[J].isQualifier;
J--)
ReturnTypeRange.setBegin(Tokens[J].T.getLocation());
ExtendedLeft = true;
}
// If we found the end of the return type, include right qualifiers.
if (SM.isBeforeInTranslationUnit(ReturnTypeRange.getEnd(),
Tokens[I].T.getLocation())) {
for (size_t J = I; J < Tokens.size() && Tokens[J].isQualifier; J++)
ReturnTypeRange.setEnd(Tokens[J].T.getLocation());
break;
}
}
assert(!ReturnTypeRange.getBegin().isMacroID() &&
"Return type source range begin must not be a macro");
assert(!ReturnTypeRange.getEnd().isMacroID() &&
"Return type source range end must not be a macro");
return ReturnTypeRange;
}
void UseTrailingReturnTypeCheck::keepSpecifiers(
std::string &ReturnType, std::string &Auto, SourceRange ReturnTypeCVRange,
const FunctionDecl &F, const FriendDecl *Fr, const ASTContext &Ctx,
const SourceManager &SM, const LangOptions &LangOpts) {
// Check if there are specifiers inside the return type. E.g. unsigned
// inline int.
const auto *M = dyn_cast<CXXMethodDecl>(&F);
if (!F.isConstexpr() && !F.isInlineSpecified() &&
F.getStorageClass() != SC_Extern && F.getStorageClass() != SC_Static &&
!Fr && !(M && M->isVirtualAsWritten()))
return;
// Tokenize return type. If it contains macros which contain a mix of
// qualifiers, specifiers and types, give up.
llvm::Optional<SmallVector<ClassifiedToken, 8>> MaybeTokens =
classifyTokensBeforeFunctionName(F, Ctx, SM, LangOpts);
if (!MaybeTokens)
return;
// Find specifiers, remove them from the return type, add them to 'auto'.
unsigned int ReturnTypeBeginOffset =
SM.getDecomposedLoc(ReturnTypeCVRange.getBegin()).second;
size_t InitialAutoLength = Auto.size();
unsigned int DeletedChars = 0;
for (ClassifiedToken CT : *MaybeTokens) {
if (SM.isBeforeInTranslationUnit(CT.T.getLocation(),
ReturnTypeCVRange.getBegin()) ||
SM.isBeforeInTranslationUnit(ReturnTypeCVRange.getEnd(),
CT.T.getLocation()))
continue;
if (!CT.isSpecifier)
continue;
// Add the token to 'auto' and remove it from the return type, including
// any whitespace following the token.
unsigned int TOffset = SM.getDecomposedLoc(CT.T.getLocation()).second;
assert(TOffset >= ReturnTypeBeginOffset &&
"Token location must be after the beginning of the return type");
unsigned int TOffsetInRT = TOffset - ReturnTypeBeginOffset - DeletedChars;
unsigned int TLengthWithWS = CT.T.getLength();
while (TOffsetInRT + TLengthWithWS < ReturnType.size() &&
llvm::isSpace(ReturnType[TOffsetInRT + TLengthWithWS]))
TLengthWithWS++;
std::string Specifier = ReturnType.substr(TOffsetInRT, TLengthWithWS);
if (!llvm::isSpace(Specifier.back()))
Specifier.push_back(' ');
Auto.insert(Auto.size() - InitialAutoLength, Specifier);
ReturnType.erase(TOffsetInRT, TLengthWithWS);
DeletedChars += TLengthWithWS;
}
}
void UseTrailingReturnTypeCheck::registerMatchers(MatchFinder *Finder) {
auto F = functionDecl(
unless(anyOf(hasTrailingReturn(), returns(voidType()),
cxxConversionDecl(), cxxMethodDecl(isImplicit()))))
.bind("Func");
Finder->addMatcher(F, this);
Finder->addMatcher(friendDecl(hasDescendant(F)).bind("Friend"), this);
}
void UseTrailingReturnTypeCheck::registerPPCallbacks(
const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
this->PP = PP;
}
void UseTrailingReturnTypeCheck::check(const MatchFinder::MatchResult &Result) {
assert(PP && "Expected registerPPCallbacks() to have been called before so "
"preprocessor is available");
const auto *F = Result.Nodes.getNodeAs<FunctionDecl>("Func");
const auto *Fr = Result.Nodes.getNodeAs<FriendDecl>("Friend");
assert(F && "Matcher is expected to find only FunctionDecls");
if (F->getLocation().isInvalid())
return;
// Skip functions which return just 'auto'.
const auto *AT = F->getDeclaredReturnType()->getAs<AutoType>();
if (AT != nullptr && !AT->isConstrained() &&
AT->getKeyword() == AutoTypeKeyword::Auto &&
!hasAnyNestedLocalQualifiers(F->getDeclaredReturnType()))
return;
// TODO: implement those
if (F->getDeclaredReturnType()->isFunctionPointerType() ||
F->getDeclaredReturnType()->isMemberFunctionPointerType() ||
F->getDeclaredReturnType()->isMemberPointerType()) {
diag(F->getLocation(), Message);
return;
}
const ASTContext &Ctx = *Result.Context;
const SourceManager &SM = *Result.SourceManager;
const LangOptions &LangOpts = getLangOpts();
const TypeSourceInfo *TSI = F->getTypeSourceInfo();
if (!TSI)
return;
FunctionTypeLoc FTL =
TSI->getTypeLoc().IgnoreParens().getAs<FunctionTypeLoc>();
if (!FTL) {
// FIXME: This may happen if we have __attribute__((...)) on the function.
// We abort for now. Remove this when the function type location gets
// available in clang.
diag(F->getLocation(), Message);
return;
}
SourceLocation InsertionLoc =
findTrailingReturnTypeSourceLocation(*F, FTL, Ctx, SM, LangOpts);
if (InsertionLoc.isInvalid()) {
diag(F->getLocation(), Message);
return;
}
// Using the declared return type via F->getDeclaredReturnType().getAsString()
// discards user formatting and order of const, volatile, type, whitespace,
// space before & ... .
SourceRange ReturnTypeCVRange =
findReturnTypeAndCVSourceRange(*F, FTL.getReturnLoc(), Ctx, SM, LangOpts);
if (ReturnTypeCVRange.isInvalid())
return;
// Check if unqualified names in the return type conflict with other entities
// after the rewrite.
// FIXME: this could be done better, by performing a lookup of all
// unqualified names in the return type in the scope of the function. If the
// lookup finds a different entity than the original entity identified by the
// name, then we can either not perform a rewrite or explicitly qualify the
// entity. Such entities could be function parameter names, (inherited) class
// members, template parameters, etc.
UnqualNameVisitor UNV{*F};
UNV.TraverseTypeLoc(FTL.getReturnLoc());
if (UNV.Collision) {
diag(F->getLocation(), Message);
return;
}
SourceLocation ReturnTypeEnd =
Lexer::getLocForEndOfToken(ReturnTypeCVRange.getEnd(), 0, SM, LangOpts);
StringRef CharAfterReturnType = Lexer::getSourceText(
CharSourceRange::getCharRange(ReturnTypeEnd,
ReturnTypeEnd.getLocWithOffset(1)),
SM, LangOpts);
bool NeedSpaceAfterAuto =
CharAfterReturnType.empty() || !llvm::isSpace(CharAfterReturnType[0]);
std::string Auto = NeedSpaceAfterAuto ? "auto " : "auto";
std::string ReturnType =
std::string(tooling::fixit::getText(ReturnTypeCVRange, Ctx));
keepSpecifiers(ReturnType, Auto, ReturnTypeCVRange, *F, Fr, Ctx, SM,
LangOpts);
diag(F->getLocation(), Message)
<< FixItHint::CreateReplacement(ReturnTypeCVRange, Auto)
<< FixItHint::CreateInsertion(InsertionLoc, " -> " + ReturnType);
}
} // namespace modernize
} // namespace tidy
} // namespace clang