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[Diagnostics] When replacing an existential parameter type with a type parameter,

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insert 'some' instead of an explicit type parameter.

Replacing 'any' with 'some' allows the code to compile without further
changes, such as naming an explicit type parameter, and is future-proofed
for same-type requirements on primary associated types instead of needing
additional logic to add a 'where' clause.
This commit is contained in:
Holly Borla
2022-04-15 22:57:56 -07:00
parent a2328b0843
commit 976addcbef
2 changed files with 73 additions and 98 deletions
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99
lib/Sema/CSDiagnostics.cpp
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@@ -3972,8 +3972,11 @@ bool InvalidMemberRefOnExistential::diagnoseAsError() {
// If the base expression is a reference to a function or subscript
// parameter, offer a fixit that replaces the existential parameter type with
// its generic equivalent, e.g. func foo(p: any P) → func foo<T: P>(p: T).
// FIXME: Add an option to use 'some' vs. an explicit generic parameter.
// its generic equivalent, e.g. func foo(p: any P) → func foo(p: some P).
// Replacing 'any' with 'some' allows the code to compile without further
// changes, such as naming an explicit type parameter, and is future-proofed
// for same-type requirements on primary associated types instead of needing
// a where clause.
if (!PD || !PD->getDeclContext()->getAsDecl())
return true;
@@ -4022,70 +4025,42 @@ bool InvalidMemberRefOnExistential::diagnoseAsError() {
if (PD->isInOut())
return true;
constexpr StringRef GPNamePlaceholder = "<#generic parameter name#>";
SourceRange TyReplacementRange;
SourceRange RemoveAnyRange;
SourceLoc GPDeclLoc;
std::string GPDeclStr;
{
llvm::raw_string_ostream OS(GPDeclStr);
auto *const GC = PD->getDeclContext()->getAsDecl()->getAsGenericContext();
if (GC->getParsedGenericParams()) {
GPDeclLoc = GC->getParsedGenericParams()->getRAngleLoc();
OS << ", ";
} else {
GPDeclLoc =
isa<AbstractFunctionDecl>(GC)
? cast<AbstractFunctionDecl>(GC)->getParameters()->getLParenLoc()
: cast<SubscriptDecl>(GC)->getIndices()->getLParenLoc();
OS << "<";
}
OS << GPNamePlaceholder << ": ";
auto *TR = PD->getTypeRepr()->getWithoutParens();
if (auto *STR = dyn_cast<SpecifierTypeRepr>(TR)) {
TR = STR->getBase()->getWithoutParens();
}
if (auto *ETR = dyn_cast<ExistentialTypeRepr>(TR)) {
TR = ETR->getConstraint();
RemoveAnyRange = SourceRange(ETR->getAnyLoc(), TR->getStartLoc());
TR = TR->getWithoutParens();
}
if (auto *MTR = dyn_cast<MetatypeTypeRepr>(TR)) {
TR = MTR->getBase();
// (P & Q).Type -> T.Type
// (P).Type -> (T).Type
// ((P & Q)).Type -> ((T)).Type
if (auto *TTR = dyn_cast<TupleTypeRepr>(TR)) {
assert(TTR->isParenType());
if (!isa<CompositionTypeRepr>(TTR->getElementType(0))) {
TR = TR->getWithoutParens();
}
}
}
TyReplacementRange = TR->getSourceRange();
// Strip any remaining parentheses and print the conformance constraint.
TR->getWithoutParens()->print(OS);
if (!GC->getParsedGenericParams()) {
OS << ">";
}
auto *typeRepr = PD->getTypeRepr()->getWithoutParens();
if (auto *STR = dyn_cast<SpecifierTypeRepr>(typeRepr)) {
typeRepr = STR->getBase()->getWithoutParens();
}
// First, replace the constraint type with the generic parameter type
// placeholder.
Diag.fixItReplace(TyReplacementRange, GPNamePlaceholder);
SourceRange anyRange;
TypeRepr *constraintRepr = typeRepr;
if (auto *existentialRepr = dyn_cast<ExistentialTypeRepr>(typeRepr)) {
constraintRepr = existentialRepr->getConstraint()->getWithoutParens();
auto anyStart = existentialRepr->getAnyLoc();
auto anyEnd = existentialRepr->getConstraint()->getStartLoc();
anyRange = SourceRange(anyStart, anyEnd);
}
// Remove 'any' if needed, using a character-based removal to pick up
bool needsParens = false;
while (auto *metatype = dyn_cast<MetatypeTypeRepr>(constraintRepr)) {
// The generic equivalent of 'any P.Type' is '(some P).Type'
constraintRepr = metatype->getBase()->getWithoutParens();
if (isa<SimpleIdentTypeRepr>(constraintRepr))
needsParens = !isa<TupleTypeRepr>(metatype->getBase());
}
std::string fix;
llvm::raw_string_ostream OS(fix);
if (needsParens)
OS << "(";
OS << "some ";
constraintRepr->print(OS);
if (needsParens)
OS << ")";
// When removing 'any', use a character-based removal to pick up
// whitespaces between it and its constraint repr.
if (RemoveAnyRange.isValid()) {
Diag.fixItRemoveChars(RemoveAnyRange.Start, RemoveAnyRange.End);
}
// Finally, insert the generic parameter declaration.
Diag.fixItInsert(GPDeclLoc, GPDeclStr);
Diag
.fixItReplace(constraintRepr->getSourceRange(), fix)
.fixItRemoveChars(anyRange.Start, anyRange.End);
return true;
}