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Improve opaque type with no RHS error message #15285

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Merged
merged 2 commits into from
May 25, 2022
Merged

Improve opaque type with no RHS error message #15285

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fa64f17
Improve opaque type with no RHS error message
nicolasstucki May 24, 2022
bccacaf
Check for missing RHS of higher-kinded opaque types
griggt May 24, 2022
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21 changes: 17 additions & 4 deletions compiler/src/dotty/tools/dotc/ast/Desugar.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1235,18 +1235,31 @@ object desugar {
rhsOK(rhs)
}

def checkOpaqueAlias(tree: MemberDef)(using Context): MemberDef =
def check(rhs: Tree): MemberDef = rhs match
case bounds: TypeBoundsTree if bounds.alias.isEmpty =>
report.error(i"opaque type must have a right-hand side", tree.srcPos)
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@griggt griggt May 24, 2022 •
edited
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Suggested change
report.error(i"opaque type must have a right-hand side", tree.srcPos)
report.error(i"opaque type must have a right-hand side", tree.srcPos.endPos)

...if we want the caret to be placed where the missing RHS should go?

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Both approaches seem reasonable to me. I do not have a preference on either option.

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Both approaches seem reasonable to me. I do not have a preference on either option.

tree.withMods(tree.mods.withoutFlags(Opaque))
case LambdaTypeTree(_, body) => check(body)
case _ => tree
if !tree.mods.is(Opaque) then tree
else tree match
case TypeDef(_, rhs) => check(rhs)
case _ => tree

/** Check that modifiers are legal for the definition `tree`.
* Right now, we only check for `opaque`. TODO: Move other modifier checks here.
*/
def checkModifiers(tree: Tree)(using Context): Tree = tree match {
case tree: MemberDef =>
var tested: MemberDef = tree
def checkApplicable(flag: Flag, test: MemberDefTest): Unit =
def checkApplicable(flag: Flag, test: MemberDefTest): MemberDef =
if (tested.mods.is(flag) && !test.applyOrElse(tree, (md: MemberDef) => false)) {
report.error(ModifierNotAllowedForDefinition(flag), tree.srcPos)
tested = tested.withMods(tested.mods.withoutFlags(flag))
}
checkApplicable(Opaque, legalOpaque)
tested.withMods(tested.mods.withoutFlags(flag))
} else tested
tested = checkOpaqueAlias(tested)
tested = checkApplicable(Opaque, legalOpaque)
tested
case _ =>
tree
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8 changes: 8 additions & 0 deletions tests/neg/i15266.check
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@@ -0,0 +1,8 @@
-- [E156] Syntax Error: tests/neg/i15266.scala:5:13 --------------------------------------------------------------------
5 |opaque class A // error
|^^^^^^^^^^^^^^
|Modifier opaque is not allowed for this definition
-- Error: tests/neg/i15266.scala:1:12 ----------------------------------------------------------------------------------
1 |opaque type Type0 // error
|^^^^^^^^^^^^^^^^^
|opaque type must have a right-hand side
5 changes: 5 additions & 0 deletions tests/neg/i15266.scala
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@@ -0,0 +1,5 @@
opaque type Type0 // error
opaque type Type1 = Int
opaque type Type2 <: Int = 2
opaque type Type3 >: 3 <: Int = 3
opaque class A // error
16 changes: 16 additions & 0 deletions tests/neg/i6055.check
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@@ -0,0 +1,16 @@
-- Error: tests/neg/i6055.scala:1:12 -----------------------------------------------------------------------------------
1 |opaque type i0 // error: opaque type must have a right-hand side
|^^^^^^^^^^^^^^
|opaque type must have a right-hand side
-- Error: tests/neg/i6055.scala:2:12 -----------------------------------------------------------------------------------
2 |opaque type i2 <: Int // error: opaque type must have a right-hand side
|^^^^^^^^^^^^^^^^^^^^^
|opaque type must have a right-hand side
-- Error: tests/neg/i6055.scala:4:12 -----------------------------------------------------------------------------------
4 |opaque type i1[_] // error: opaque type must have a right-hand side
|^^^^^^^^^^^^^^^^^
|opaque type must have a right-hand side
-- Error: tests/neg/i6055.scala:5:12 -----------------------------------------------------------------------------------
5 |opaque type x[_] <: Int // error: opaque type must have a right-hand side
|^^^^^^^^^^^^^^^^^^^^^^^
|opaque type must have a right-hand side
8 changes: 4 additions & 4 deletions tests/neg/i6055.scala
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@@ -1,5 +1,5 @@
opaque type i0 // error: opaque type must be an alias type
opaque type i2 <: Int // error: opaque type must be an alias type
opaque type i0 // error: opaque type must have a right-hand side
opaque type i2 <: Int // error: opaque type must have a right-hand side

opaque type i1[_] // error: opaque type must be an alias type
opaque type x[_] <: Int // error: opaque type must be an alias type
opaque type i1[_] // error: opaque type must have a right-hand side
opaque type x[_] <: Int // error: opaque type must have a right-hand side