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Amend SE-0224 to include #if compiler as well. #897

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Sep 4, 2018
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Amend SE-0224 to include #if compiler as well. #897

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12 changes: 10 additions & 2 deletions proposals/0224-ifswift-lessthan-operator.md
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,10 @@ code:
#if !swift(>=4.2)
// This will only be executed if the Swift version is less than 4.2.
#endif

#if !compiler(>=4.2)
// This will only be executed if the Swift compiler version is less than 4.2.
#endif
```

With the introduction of support for the "<" unary operator, the
Expand All @@ -39,6 +43,10 @@ refactored code would be more clear and readable:
#if swift(<4.2)
// This will only be executed if the Swift version is less than 4.2.
#endif

#if compiler(<4.2)
// This will only be executed if the Swift compiler version is less than 4.2.
#endif
```

In the former snippet, the `!` can be easily missed in a code
Expand All @@ -53,8 +61,8 @@ example.
## Proposed solution

The solution is small change in the parser so that the operator "<" is
supported. Diagnostic messages about invalid unary operators must be
updated as well.
supported for both the `#if swift` and `#if compiler` conditions. Diagnostic
messages about invalid unary operators must be updated as well.

## Detailed design

Expand Down