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Improve recovery of misplaced attributes on statements #1282

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Merged
merged 1 commit into from
Jan 27, 2023
Merged

Improve recovery of misplaced attributes on statements #1282

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5 changes: 5 additions & 0 deletions Sources/SwiftParser/Statements.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,11 @@ extension TokenConsumer {
/// - Seealso: ``Parser/parseStatement()``
func atStartOfStatement(allowRecovery: Bool = false) -> Bool {
var lookahead = self.lookahead()
if allowRecovery {
// Attributes are not allowed on statements. But for recovery, skip over
// misplaced attributes.
_ = lookahead.consumeAttributeList()
}
return lookahead.isStartOfStatement(allowRecovery: allowRecovery)
}
}
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4 changes: 1 addition & 3 deletions Sources/SwiftParser/TokenPrecedence.swift
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Expand Up @@ -135,7 +135,7 @@ public enum TokenPrecedence: Comparable {
case // Chaining punctuators
.infixQuestionMark, .period, .postfixQuestionMark, .exclamationMark,
// Misc
.backslash, .backtick, .colon, .comma, .ellipsis, .equal, .prefixAmpersand:
.atSign, .backslash, .backtick, .colon, .comma, .ellipsis, .equal, .prefixAmpersand:
self = .weakPunctuator

// MARK: Weak bracket close
Expand All @@ -159,8 +159,6 @@ public enum TokenPrecedence: Comparable {
.semicolon,
// Arrow is a strong indicator in a function type that we are now in the return type
.arrow,
// '@' typically occurs at the start of declarations
.atSign,
// EOF is here because it is a very stong marker and doesn't belong anywhere else
.eof:
self = .strongPunctuator
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4 changes: 2 additions & 2 deletions Tests/SwiftParserTest/StatementTests.swift
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Expand Up @@ -265,8 +265,8 @@ final class StatementTests: XCTestCase {
}
""",
diagnostics: [
DiagnosticSpec(locationMarker: "1️⃣", message: "unexpected code '@s return' in function"),
DiagnosticSpec(locationMarker: "2️⃣", message: "unexpected code '@unknown return' in function"),
DiagnosticSpec(locationMarker: "1️⃣", message: "unexpected code '@s' before 'return' statement"),
DiagnosticSpec(locationMarker: "2️⃣", message: "unexpected code '@unknown' before 'return' statement"),
]
)
}
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11 changes: 5 additions & 6 deletions Tests/SwiftParserTest/translated/SwitchTests.swift
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Expand Up @@ -950,7 +950,7 @@ final class SwitchTests: XCTestCase {
}
""",
diagnostics: [
DiagnosticSpec(message: "expected label in switch case")
DiagnosticSpec(message: "unexpected code '@moreGarbage' in switch case")
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Do we parse any single attribute rather than just @unknown?

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Yes, we do. That’s what the syntax tree currently allows.

]
)
}
Expand Down Expand Up @@ -986,22 +986,21 @@ final class SwitchTests: XCTestCase {
switch Whatever.Thing {
case .Thing:
break
@unknown2️⃣
@unknown
2️⃣@unknown
case _:
break
}
switch Whatever.Thing {
@unknown 3️⃣@garbage4️⃣(foobar)
@unknown 3️⃣@garbage(foobar)
case _:
break
}
""",
diagnostics: [
DiagnosticSpec(locationMarker: "1️⃣", message: "unexpected code '(garbage)' in switch case"),
DiagnosticSpec(locationMarker: "2️⃣", message: "expected label in switch case"),
DiagnosticSpec(locationMarker: "3️⃣", message: "expected label in switch case"),
DiagnosticSpec(locationMarker: "4️⃣", message: "unexpected code '(foobar)' in switch case"),
DiagnosticSpec(locationMarker: "2️⃣", message: "unexpected code '@unknown' in switch case"),
DiagnosticSpec(locationMarker: "3️⃣", message: "unexpected code '@garbage(foobar)' in switch case"),
]
)
}
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