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Commit 07611bf

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Put extensions under language.experimental.relaxedLambdaSyntax
1 parent 8665a3c commit 07611bf

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10 files changed

+41
-20
lines changed

10 files changed

+41
-20
lines changed

‎compiler/src/dotty/tools/dotc/config/Feature.scala‎

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Original file line numberDiff line numberDiff line change
@@ -38,6 +38,7 @@ object Feature:
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val quotedPatternsWithPolymorphicFunctions = experimental("quotedPatternsWithPolymorphicFunctions")
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val packageObjectValues = experimental("packageObjectValues")
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val subCases = experimental("subCases")
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val relaxedLambdaSyntax = experimental("relaxedLambdaSyntax")
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def experimentalAutoEnableFeatures(using Context): List[TermName] =
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defn.languageExperimentalFeatures

‎compiler/src/dotty/tools/dotc/parsing/Parsers.scala‎

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Original file line numberDiff line numberDiff line change
@@ -1086,18 +1086,20 @@ object Parsers {
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/** Is the token sequence following the current `:` token classified as a lambda?
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* If yes return a defined parsing function to parse the lambda body, if not
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* return None. The case is triggered in two :if the input starts with an identifier,
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* a wildcard, or something enclosed in (...) or [...], this is followed by a
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* `=>` or `?=>`, one one of the following two cases applies:
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* 1. The next token is an indent. In this case the return parsing function parses
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* an Expr in location Location.InColonArg.
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* 2. The next token is on the same line and the enclosing region is not `(...)`.
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* In this case the parsing function parses an Expr in location Location.InColonArg
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* enclosed in a SingleLineLambda region, and then eats the ENDlambda token
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* generated by the Scanner at the end of that region.
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* The reason for excluding (2) in regions enclosed in parentheses is to avoid
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* an ambiguity with type ascription `(x: A => B)`, where function types are only
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* allowed inside parentheses.
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* return None. The case is triggered in two situations:
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* 1. If the input starts with an identifier, a wildcard, or something
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* enclosed in (...) or [...], this is followed by a `=>` or `?=>`,
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* and one of the following two subcases applies:
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* 1a. The next token is an indent. In this case the return parsing function parses
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* an Expr in location Location.InColonArg.
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* 1b. Under relaxedLambdaSyntax: the next token is on the same line and the enclosing region is not `(...)`.
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* In this case the parsing function parses an Expr in location Location.InColonArg
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* enclosed in a SingleLineLambda region, and then eats the ENDlambda token
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* generated by the Scanner at the end of that region.
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* The reason for excluding (1b) in regions enclosed in parentheses is to avoid
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* an ambiguity with type ascription `(x: A => B)`, where function types are only
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* allowed inside parentheses.
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* 2. Under relaxedLambdaSyntax: the input starts with a `case`.
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*/
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def followingIsLambdaAfterColon(): Option[() => Tree] =
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val lookahead = in.LookaheadScanner(allowIndent = true)
@@ -1107,7 +1109,9 @@ object Parsers {
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lookahead.observeArrowIndented()
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if lookahead.token == INDENT || lookahead.token == EOF then
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Some(() => expr(Location.InColonArg))
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else if !in.currentRegion.isInstanceOf[InParens] then
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else if in.featureEnabled(Feature.relaxedLambdaSyntax)
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&& !in.currentRegion.isInstanceOf[InParens]
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then
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Some: () =>
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val t = inSepRegion(SingleLineLambda(_)):
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expr(Location.InColonArg)
@@ -1122,7 +1126,7 @@ object Parsers {
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else if lookahead.token == LPAREN || lookahead.token == LBRACKET then
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lookahead.skipParens()
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isArrowIndent()
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else if lookahead.token == CASE then
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else if lookahead.token == CASE && in.featureEnabled(Feature.relaxedLambdaSyntax) then
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Some(() => singleCaseMatch())
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else
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None
@@ -1193,9 +1197,11 @@ object Parsers {
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/** Optionally, if we are seeing a lambda argument after a colon of the form
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* : (params) =>
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* body
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* or a single-line lambda
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* or a single-line lambda (under relaxedLambdaSyntax)
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* : (params) => body
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* then return the function used to parse `body`.
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* or a case clause (under relaxedLambdaSyntax)
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* : case pat guard => rhs
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* then return the function used to parse `body` or the case clause.
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*/
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def detectColonLambda: Option[() => Tree] =
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if sourceVersion.enablesFewerBraces && in.token == COLONfollow
@@ -2432,7 +2438,7 @@ object Parsers {
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val arrowOffset = accept(ARROW)
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val body = expr(location)
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makePolyFunction(tparams, body, "literal", errorTermTree(arrowOffset), start, arrowOffset)
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case CASE =>
2441+
case CASE if in.featureEnabled(Feature.relaxedLambdaSyntax) =>
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singleCaseMatch()
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case _ =>
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val saved = placeholderParams

‎library/src/scala/language.scala‎

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@@ -355,6 +355,10 @@ object language {
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@compileTimeOnly("`subCases` can only be used at compile time in import statements")
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object subCases
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/** Experimental support for single-line lambdas and case clause expressions after `:`
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*/
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@compileTimeOnly("`relaxedLambdaSyntax` can only be used at compile time in import statements")
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object relaxedLambdaSyntax
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}
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/** The deprecated object contains features that are no longer officially suypported in Scala.

‎library/src/scala/runtime/stdLibPatches/language.scala‎

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@@ -161,6 +161,11 @@ object language:
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*/
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@compileTimeOnly("`subCases` can only be used at compile time in import statements")
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object subCases
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/** Experimental support for single-line lambdas and case clause expressions after `:`
166+
*/
167+
@compileTimeOnly("`relaxedLambdaSyntax` can only be used at compile time in import statements")
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object relaxedLambdaSyntax
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end experimental
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/** The deprecated object contains features that are no longer officially suypported in Scala.

‎tests/neg/closure-args.scala‎

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@@ -1,4 +1,4 @@
1-
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importlanguage.experimental.relaxedLambdaSyntax
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val x = List(1).map: (x: => Int) => // error
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???
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val z = List(1).map: + => // ok

‎tests/neg/i22193.scala‎

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@@ -1,4 +1,4 @@
1-
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importlanguage.experimental.relaxedLambdaSyntax
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def fn2(arg: String, arg2: String)(f: String => Unit): Unit = f(arg)
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def fn3(arg: String, arg2: String)(f: => Unit): Unit = f

‎tests/neg/i22906.scala‎

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Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
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//> using options -rewrite -indent
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//> nominally using scala 3.7.0-RC1
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// does not reproduce under "vulpix" test rig, which enforces certain flag sets?
4-
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importlanguage.experimental.relaxedLambdaSyntax
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def program: Int => Int =
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{`1`: Int => 5} // error // error

‎tests/pos/change-lambda.scala‎

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@@ -1,3 +1,5 @@
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import language.experimental.relaxedLambdaSyntax
2+
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def foo(x: Any) = ???
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def test(xs: List[Int]) =

‎tests/pos/closure-args.scala‎

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Original file line numberDiff line numberDiff line change
@@ -1,3 +1,4 @@
1+
import language.experimental.relaxedLambdaSyntax
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val z = List(1).map: + => // ok
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???

‎tests/run/single-case-expr.scala‎

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@@ -1,3 +1,5 @@
1+
import language.experimental.relaxedLambdaSyntax
2+
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case class Foo(x: Int, y: Int)
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@main def Test =
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val f: List[Int] => Int = case y :: ys => y

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