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Merged
merged 2 commits into from
Nov 10, 2019
Merged

Improve warning for inferring an undesirable type #27797

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4a222a0
[Sema][Diagnostics] Add fixit for warning when inferring an undesirab…
jder Oct 19, 2019
502691f
[Sema][Diagnostics] Generalize undesirable type warning to include ar…
jder Oct 19, 2019
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17 changes: 9 additions & 8 deletions lib/Sema/TypeCheckPattern.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -978,12 +978,10 @@ bool TypeChecker::coercePatternToType(Pattern *&P, TypeResolution resolution,
TypeChecker::checkForForbiddenPrefix(Context, var->getBaseName());

// If we are inferring a variable to have type AnyObject.Type,
// "()", an uninhabited type, or optional thereof, emit a diagnostic.
// In the first 2 cases, the coder probably forgot a cast and expected a
// concrete type. In the later case, they probably didn't mean to bind to
// a variable, or there is some other bug. We always tell them that they
// can silence the warning with an explicit type annotation
// (and provide a fixit) as a note.
// "()", "[()]", an uninhabited type, or optional thereof, emit a diagnostic.
// They are probably missing a cast or didn't mean to bind to a variable.
// We always tell them that they can silence the warning with an
// explicit type annotation (and provide a fixit) as a note.
Type diagTy = type->lookThroughAllOptionalTypes();
bool isOptional = !type->getOptionalObjectType().isNull();
if (!diagTy) diagTy = type;
Expand All @@ -1010,6 +1008,9 @@ bool TypeChecker::coercePatternToType(Pattern *&P, TypeResolution resolution,
assert((diagTy->is<EnumType>() || diagTy->is<BoundGenericEnumType>()) &&
"unknown structurally uninhabited type");
}
} else if (auto *BST = diagTy->getAs<BoundGenericStructType>()) {
if (BST->getDecl() == Context.getArrayDecl())
shouldRequireType = BST->getGenericArgs()[0]->isEqual(Context.TheEmptyTupleType);
}

if (shouldRequireType &&
Expand All @@ -1018,8 +1019,8 @@ bool TypeChecker::coercePatternToType(Pattern *&P, TypeResolution resolution,
!(options & TypeResolutionFlags::FromNonInferredPattern)) {
diags.diagnose(NP->getLoc(), diag, NP->getDecl()->getName(), type,
NP->getDecl()->isLet());
diags.diagnose(NP->getLoc(),
diag::add_explicit_type_annotation_to_silence);
diags.diagnose(NP->getLoc(), diag::add_explicit_type_annotation_to_silence)
.fixItInsertAfter(var->getNameLoc(), ": " + type->getWithoutParens()->getString());
}

return false;
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24 changes: 24 additions & 0 deletions test/SourceKit/Sema/placeholders.swift.placeholders.response
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Expand Up @@ -27,5 +27,29 @@
key.length: 9
}
]
},
{
key.line: 8,
key.column: 5,
key.filepath: placeholders.swift,
key.severity: source.diagnostic.severity.warning,
key.description: "constant 'myArray' inferred to have type '[()]', which may be unexpected",
key.diagnostic_stage: source.diagnostic.stage.swift.sema,
key.diagnostics: [
{
key.line: 8,
key.column: 5,
key.filepath: placeholders.swift,
key.severity: source.diagnostic.severity.note,
key.description: "add an explicit type annotation to silence this warning",
key.fixits: [
{
key.offset: 236,
key.length: 0,
key.sourcetext: ": [()]"
}
]
}
]
}
]
2 changes: 1 addition & 1 deletion test/decl/var/lazy_properties.swift
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Expand Up @@ -112,7 +112,7 @@ struct Outer {

lazy var y = {_ = 3}()
// expected-warning@-1 {{variable 'y' inferred to have type '()', which may be unexpected}}
// expected-note@-2 {{add an explicit type annotation to silence this warning}}
// expected-note@-2 {{add an explicit type annotation to silence this warning}} {{15-15=: ()}}
}
}

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10 changes: 5 additions & 5 deletions test/decl/var/properties.swift
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Expand Up @@ -1272,11 +1272,11 @@ class WeakFixItTest {

// SR-8811 (Warning)

let sr8811a = fatalError() // expected-warning {{constant 'sr8811a' inferred to have type 'Never', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
let sr8811a = fatalError() // expected-warning {{constant 'sr8811a' inferred to have type 'Never', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}} {{12-12=: Never}}

let sr8811b: Never = fatalError() // Ok

let sr8811c = (16, fatalError()) // expected-warning {{constant 'sr8811c' inferred to have type '(Int, Never)', which contains an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
let sr8811c = (16, fatalError()) // expected-warning {{constant 'sr8811c' inferred to have type '(Int, Never)', which contains an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}} {{12-12=: (Int, Never)}}

let sr8811d: (Int, Never) = (16, fatalError()) // Ok

Expand All @@ -1292,11 +1292,11 @@ class SR_10995 {
}

func sr_10995_foo() {
let doubleOptionalNever = makeDoubleOptionalNever() // expected-warning {{constant 'doubleOptionalNever' inferred to have type 'Never??', which may be unexpected}}
// expected-note@-1 {{add an explicit type annotation to silence this warning}}
let doubleOptionalNever = makeDoubleOptionalNever() // expected-warning {{constant 'doubleOptionalNever' inferred to have type 'Never??', which may be unexpected}}
// expected-note@-1 {{add an explicit type annotation to silence this warning}} {{28-28=: Never??}}
// expected-warning@-2 {{initialization of immutable value 'doubleOptionalNever' was never used; consider replacing with assignment to '_' or removing it}}
let singleOptionalNever = makeSingleOptionalNever() // expected-warning {{constant 'singleOptionalNever' inferred to have type 'Never?', which may be unexpected}}
// expected-note@-1 {{add an explicit type annotation to silence this warning}}
// expected-note@-1 {{add an explicit type annotation to silence this warning}} {{28-28=: Never?}}
// expected-warning@-2 {{initialization of immutable value 'singleOptionalNever' was never used; consider replacing with assignment to '_' or removing it}}
}
}
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14 changes: 12 additions & 2 deletions test/decl/var/variables.swift
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Expand Up @@ -36,15 +36,15 @@ struct Broken {

// rdar://16252090 - Warning when inferring empty tuple type for declarations
var emptyTuple = testShadowing() // expected-warning {{variable 'emptyTuple' inferred to have type '()'}} \
// expected-note {{add an explicit type annotation to silence this warning}}
// expected-note {{add an explicit type annotation to silence this warning}} {{15-15=: ()}}

// rdar://15263687 - Diagnose variables inferenced to 'AnyObject'
var ao1 : AnyObject
var ao2 = ao1

var aot1 : AnyObject.Type
var aot2 = aot1 // expected-warning {{variable 'aot2' inferred to have type 'AnyObject.Type', which may be unexpected}} \
// expected-note {{add an explicit type annotation to silence this warning}}
// expected-note {{add an explicit type annotation to silence this warning}} {{9-9=: AnyObject.Type}}


for item in [AnyObject]() { // No warning in for-each loop.
Expand All @@ -60,6 +60,16 @@ func testAnyObjectOptional() -> AnyObject? {
return x
}

// SR-11511 Warning for inferring an array of empty tuples
var arrayOfEmptyTuples = [""].map { print($0) } // expected-warning {{variable 'arrayOfEmptyTuples' inferred to have type '[()]'}} \
// expected-note {{add an explicit type annotation to silence this warning}} {{23-23=: [()]}}

var maybeEmpty = Optional(arrayOfEmptyTuples) // expected-warning {{variable 'maybeEmpty' inferred to have type '[()]?'}} \
// expected-note {{add an explicit type annotation to silence this warning}} {{15-15=: [()]?}}

var shouldWarnWithoutSugar = (arrayOfEmptyTuples as Array<()>) // expected-warning {{variable 'shouldWarnWithoutSugar' inferred to have type 'Array<()>'}} \
// expected-note {{add an explicit type annotation to silence this warning}} {{27-27=: Array<()>}}

class SomeClass {}

// <rdar://problem/16877304> weak let's should be rejected
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4 changes: 2 additions & 2 deletions test/expr/expressions.swift
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Expand Up @@ -588,9 +588,9 @@ func conversionTest(_ a: inout Double, b: inout Int) {
var pi_f3 = float.init(getPi()) // expected-error {{ambiguous use of 'init(_:)'}}
var pi_f4 = float.init(pi_f)

var e = Empty(f) // expected-warning {{variable 'e' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
var e = Empty(f) // expected-warning {{variable 'e' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}} {{8-8=: Empty}}
var e2 = Empty(d) // expected-error{{cannot convert value of type 'Double' to expected argument type 'Float'}}
var e3 = Empty(Float(d)) // expected-warning {{variable 'e3' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}}
var e3 = Empty(Float(d)) // expected-warning {{variable 'e3' inferred to have type 'Empty', which is an enum with no cases}} expected-note {{add an explicit type annotation to silence this warning}} {{9-9=: Empty}}
}

struct Rule {
Expand Down