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b3c5fde118
Introduce support for parsing declaration attributes that occur within
example:
#if hasAttribute(frozen)
@frozen
#endif
public struct X { ... }
will apply to "frozen" attribute to the struct `X`, but only when the
compiler supports the "frozen" attribute.
Correctly determining whether a particular `#if` block contains
attributes to be associated with the following declaration vs.
starting a new declaration requires arbitrary lookahead. The parser
will ensure that at least one of the branches of the `#if` contains an
attribute, and that none of the branches contains something that does
not fit the attribute grammar, before committing to parsing the `#if`
clause as part of the declaration attributes. This lookahead does
occur at the top level (e.g., in the parsing of top-level declarations
and code), but should only need to scan past the first `#if` line to
the following token in the common case.
Unlike other `#if` when used to wrap statements or declarations, we
make no attempt to record the `#if` not taken anywhere in the AST.
This reflects a change in attitude in the design of the AST, because
we have found that trying to represent this information there (e.g.,
via `IfConfigDecl`) complicates clients while providing little value.
This information is best kept in the syntax tree, only.
95 lines
1.3 KiB
Swift
95 lines
1.3 KiB
Swift
// RUN: %target-typecheck-verify-swift
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#if hasAttribute(foo)
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@foo(this is gibberish)
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#endif
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struct S1 { }
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@frozen
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#if hasAttribute(foo)
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@foo
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#endif
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public struct S2 { }
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#if hasAttribute(foo)
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@foo
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#endif
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@inlinable
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func f1() { }
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#if hasAttribute(foo)
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@foo
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#else
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@available(*, deprecated, message: "nope")
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@frozen
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#endif
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public struct S3 { }
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// Nested #if
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#if hasAttribute(foo)
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@foo
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#elseif hasAttribute(available)
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@available(*, deprecated, message: "nope")
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#if hasAttribute(frozen)
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@frozen
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#endif
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#endif
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public struct S4 { }
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// Nested in a type
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struct Inner {
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#if hasAttribute(foo)
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@foo(this is gibberish)
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#endif
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struct S1 { }
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@frozen
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#if hasAttribute(foo)
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#if hasAttribute(bar)
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@foo @bar
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#endif
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#endif
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public struct S2 { }
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#if hasAttribute(foo)
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@foo
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#endif
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@inlinable
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func f1() { }
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#if hasAttribute(foo)
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@foo
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#else
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@available(*, deprecated, message: "nope")
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@frozen
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#endif
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public struct S3 { }
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}
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// Nested in a function
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func f2() {
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#if hasAttribute(foo)
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@foo(this is gibberish)
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#endif
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struct S1 { }
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@available(*, deprecated)
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#if hasAttribute(foo)
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@foo
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#endif
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struct S2 { }
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#if hasAttribute(foo)
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@foo
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#endif
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@available(*, deprecated)
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func f1() { }
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#if hasAttribute(foo)
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@foo
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#else
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@available(*, deprecated, message: "nope")
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#endif
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struct S3 { }
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}
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