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Just warn on type ascription on a pattern #17454

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merged 2 commits into from May 12, 2023
Merged

Just warn on type ascription on a pattern #17454

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b65ef59
Raise a warning instead of an error for a type ascription on a patter…
prolativ May 10, 2023
07c395b
* Preserve the more restrictive syntax for typed patterns in the lang…
prolativ May 11, 2023
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13 changes: 12 additions & 1 deletion compiler/src/dotty/tools/dotc/parsing/Parsers.scala
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Expand Up @@ -2878,7 +2878,18 @@ object Parsers {
*/
def pattern1(location: Location = Location.InPattern): Tree =
val p = pattern2()
if (isVarPattern(p) || p.isInstanceOf[Number]) && in.isColon then
if in.isColon then
val isVariableOrNumber = isVarPattern(p) || p.isInstanceOf[Number]
if !isVariableOrNumber then
report.gradualErrorOrMigrationWarning(
em"""Type ascriptions after patterns other than:
| * variable pattern, e.g. `case x: String =>`
| * number literal pattern, e.g. `case 10.5: Double =>`
|are no longer supported. Remove the type ascription or move it to a separate variable pattern.""",
in.sourcePos(),
warnFrom = `3.3`,
errorFrom = future
)
in.nextToken()
ascription(p, location)
else p
Expand Down
1 change: 1 addition & 0 deletions compiler/test/dotty/tools/dotc/CompilationTests.scala
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Expand Up @@ -185,6 +185,7 @@ class CompilationTests {
compileFile("tests/neg-custom-args/i13026.scala", defaultOptions.and("-print-lines")),
compileFile("tests/neg-custom-args/i13838.scala", defaultOptions.and("-Ximplicit-search-limit", "1000")),
compileFile("tests/neg-custom-args/jdk-9-app.scala", defaultOptions.and("-release:8")),
compileFile("tests/neg-custom-args/i10994.scala", defaultOptions.and("-source", "future")),
).checkExpectedErrors()
}

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4 changes: 2 additions & 2 deletions docs/_docs/internals/syntax.md
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Expand Up @@ -315,8 +315,8 @@ TypeCaseClause ::= ‘case’ (InfixType | ‘_’) ‘=>’ Type [semi]

Pattern ::= Pattern1 { ‘|’ Pattern1 } Alternative(pats)
Pattern1 ::= PatVar ‘:’ RefinedType Bind(name, Typed(Ident(wildcard), tpe))
| [‘-’] integerLiteral ‘:’ RefinedType Typed(pat, tpe)
| [‘-’] floatingPointLiteral ‘:’ RefinedType Typed(pat, tpe)
| [‘-’] integerLiteral ‘:’ RefinedType Typed(pat, tpe)
| [‘-’] floatingPointLiteral ‘:’ RefinedType Typed(pat, tpe)
| Pattern2
Pattern2 ::= [id ‘@’] InfixPattern [‘*’] Bind(name, pat)
InfixPattern ::= SimplePattern { id [nl] SimplePattern } InfixOp(pat, op, pat)
Expand Down
4 changes: 2 additions & 2 deletions docs/_docs/reference/syntax.md
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Expand Up @@ -313,8 +313,8 @@ TypeCaseClause ::= ‘case’ (InfixType | ‘_’) ‘=>’ Type [semi]

Pattern ::= Pattern1 { ‘|’ Pattern1 }
Pattern1 ::= PatVar ‘:’ RefinedType
| [‘-’] integerLiteral ‘:’ RefinedType
| [‘-’] floatingPointLiteral ‘:’ RefinedType
| [‘-’] integerLiteral ‘:’ RefinedType
| [‘-’] floatingPointLiteral ‘:’ RefinedType
| Pattern2
Pattern2 ::= [id ‘@’] InfixPattern [‘*’]
InfixPattern ::= SimplePattern { id [nl] SimplePattern }
Expand Down
0 tests/neg/i10994.scala → ...g-custom-args/fatal-warnings/i10994.scala
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6 changes: 3 additions & 3 deletions tests/neg/i15893.scala → ...g-custom-args/fatal-warnings/i15893.scala
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Expand Up @@ -22,7 +22,7 @@ transparent inline def transparentInlineMod2(inline n: NatT): NatT = inline n m
case Succ(Zero()) => Succ(Zero())
case Succ(Succ(predPredN)) => transparentInlineMod2(predPredN)

def dependentlyTypedMod2[N <: NatT](n: N): Mod2[N] = n match // exhaustivity warning; unexpected
def dependentlyTypedMod2[N <: NatT](n: N): Mod2[N] = n match
case Zero(): Zero => Zero() // error
case Succ(Zero()): Succ[Zero] => Succ(Zero()) // error
case Succ(Succ(predPredN)): Succ[Succ[_]] => dependentlyTypedMod2(predPredN) // error
Expand Down Expand Up @@ -57,5 +57,5 @@ inline def transparentInlineFoo(inline n: NatT): NatT = inline transparentInline
println(transparentInlineMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
println(transparentInlineFoo(Succ(Succ(Succ(Zero()))))) // prints Zero(), as expected
println(dependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // runtime error; unexpected
// println(inlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // doesn't compile; unexpected
// println(transparentInlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // doesn't compile; unexpected
println(inlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
println(transparentInlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
7 changes: 7 additions & 0 deletions tests/neg-custom-args/i10994.check
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@@ -0,0 +1,7 @@
-- Error: tests/neg-custom-args/i10994.scala:2:19 ----------------------------------------------------------------------
2 | case (b: Boolean): Boolean => () // error
| ^
| Type ascriptions after patterns other than:
| * variable pattern, e.g. `case x: String =>`
| * number literal pattern, e.g. `case 10.5: Double =>`
| are no longer supported. Remove the type ascription or move it to a separate variable pattern.
2 changes: 2 additions & 0 deletions tests/neg-custom-args/i10994.scala
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@@ -0,0 +1,2 @@
def foo = true match
case (b: Boolean): Boolean => () // error
13 changes: 10 additions & 3 deletions tests/neg/t5702-neg-bad-and-wild.check
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Expand Up @@ -10,10 +10,10 @@
| pattern expected
|
| longer explanation available when compiling with `-explain`
-- [E040] Syntax Error: tests/neg/t5702-neg-bad-and-wild.scala:13:22 ---------------------------------------------------
-- [E040] Syntax Error: tests/neg/t5702-neg-bad-and-wild.scala:13:23 ---------------------------------------------------
13 | case List(1, _*3:) => // error // error
| ^
| ')' expected, but ':' found
| ^
| an identifier expected, but ')' found
-- [E032] Syntax Error: tests/neg/t5702-neg-bad-and-wild.scala:15:18 ---------------------------------------------------
15 | case List(x*, 1) => // error: pattern expected
| ^
Expand Down Expand Up @@ -56,6 +56,13 @@
| Recursive value $1$ needs type
|
| longer explanation available when compiling with `-explain`
-- Warning: tests/neg/t5702-neg-bad-and-wild.scala:13:22 ---------------------------------------------------------------
13 | case List(1, _*3:) => // error // error
| ^
| Type ascriptions after patterns other than:
| * variable pattern, e.g. `case x: String =>`
| * number literal pattern, e.g. `case 10.5: Double =>`
| are no longer supported. Remove the type ascription or move it to a separate variable pattern.
-- Warning: tests/neg/t5702-neg-bad-and-wild.scala:22:20 ---------------------------------------------------------------
22 | val K(x @ _*) = k
| ^
Expand Down
6 changes: 3 additions & 3 deletions tests/pending/run/i15893.scala
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Expand Up @@ -24,7 +24,7 @@ transparent inline def transparentInlineMod2(inline n: NatT): NatT = inline n m
case Succ(Zero()) => Succ(Zero())
case Succ(Succ(predPredN)) => transparentInlineMod2(predPredN)
*/
def dependentlyTypedMod2[N <: NatT](n: N): Mod2[N] = n match // exhaustivity warning; unexpected
def dependentlyTypedMod2[N <: NatT](n: N): Mod2[N] = n match
case Zero(): Zero => Zero()
case Succ(Zero()): Succ[Zero] => Succ(Zero())
case Succ(Succ(predPredN)): Succ[Succ[_]] => dependentlyTypedMod2(predPredN)
Expand Down Expand Up @@ -61,5 +61,5 @@ inline def transparentInlineFoo(inline n: NatT): NatT = inline transparentInline
println(transparentInlineFoo(Succ(Succ(Succ(Zero()))))) // prints Zero(), as expected
*/
println(dependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // runtime error; unexpected
// println(inlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // doesn't compile; unexpected
// println(transparentInlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // doesn't compile; unexpected
// println(inlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
// println(transparentInlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
2 changes: 2 additions & 0 deletions tests/pos/i10994.scala
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@@ -0,0 +1,2 @@
def foo = true match
case (b: Boolean): Boolean => () // warning
61 changes: 61 additions & 0 deletions tests/pos/i15893.scala
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@@ -0,0 +1,61 @@
sealed trait NatT
case class Zero() extends NatT
case class Succ[+N <: NatT](n: N) extends NatT

type Mod2[N <: NatT] <: NatT = N match
case Zero => Zero
case Succ[Zero] => Succ[Zero]
case Succ[Succ[predPredN]] => Mod2[predPredN]

def mod2(n: NatT): NatT = n match
case Zero() => Zero()
case Succ(Zero()) => Succ(Zero())
case Succ(Succ(predPredN)) => mod2(predPredN)

inline def inlineMod2(inline n: NatT): NatT = inline n match
case Zero() => Zero()
case Succ(Zero()) => Succ(Zero())
case Succ(Succ(predPredN)) => inlineMod2(predPredN)

transparent inline def transparentInlineMod2(inline n: NatT): NatT = inline n match
case Zero() => Zero()
case Succ(Zero()) => Succ(Zero())
case Succ(Succ(predPredN)) => transparentInlineMod2(predPredN)

def dependentlyTypedMod2[N <: NatT](n: N): Mod2[N] = n match
case Zero(): Zero => Zero() // warning
case Succ(Zero()): Succ[Zero] => Succ(Zero()) // warning
case Succ(Succ(predPredN)): Succ[Succ[_]] => dependentlyTypedMod2(predPredN) // warning

inline def inlineDependentlyTypedMod2[N <: NatT](inline n: N): Mod2[N] = inline n match
case Zero(): Zero => Zero() // warning
case Succ(Zero()): Succ[Zero] => Succ(Zero()) // warning
case Succ(Succ(predPredN)): Succ[Succ[_]] => inlineDependentlyTypedMod2(predPredN) // warning

transparent inline def transparentInlineDependentlyTypedMod2[N <: NatT](inline n: N): Mod2[N] = inline n match
case Zero(): Zero => Zero() // warning
case Succ(Zero()): Succ[Zero] => Succ(Zero()) // warning
case Succ(Succ(predPredN)): Succ[Succ[_]] => transparentInlineDependentlyTypedMod2(predPredN) // warning

def foo(n: NatT): NatT = mod2(n) match
case Succ(Zero()) => Zero()
case _ => n

inline def inlineFoo(inline n: NatT): NatT = inline inlineMod2(n) match
case Succ(Zero()) => Zero()
case _ => n

inline def transparentInlineFoo(inline n: NatT): NatT = inline transparentInlineMod2(n) match
case Succ(Zero()) => Zero()
case _ => n

@main def main(): Unit =
println(mod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
println(foo(Succ(Succ(Succ(Zero()))))) // prints Zero(), as expected
println(inlineMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
println(inlineFoo(Succ(Succ(Succ(Zero()))))) // prints Succ(Succ(Succ(Zero()))); unexpected
println(transparentInlineMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
println(transparentInlineFoo(Succ(Succ(Succ(Zero()))))) // prints Zero(), as expected
println(dependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // runtime error; unexpected
println(inlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected
println(transparentInlineDependentlyTypedMod2(Succ(Succ(Succ(Zero()))))) // prints Succ(Zero()), as expected