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Add error message for companion and class/module name clash #3361

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Merged
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Oct 22, 2017
Merged

Add error message for companion and class/module name clash #3361

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f9af73d
Add error message for companion and class/module name clash
rsoeldner Oct 20, 2017
6e0686c
Change explanation and message
rsoeldner Oct 22, 2017
d6a5774
Change test as discussed on PR
rsoeldner Oct 22, 2017
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1 change: 1 addition & 0 deletions compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java
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Expand Up @@ -103,6 +103,7 @@ public enum ErrorMessageID {
ExtendFinalClassID,
EnumCaseDefinitionInNonEnumOwnerID,
ExpectedTypeBoundOrEqualsID,
ClassAndCompanionNameClashID,
;

public int errorNumber() {
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10 changes: 10 additions & 0 deletions compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
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Expand Up @@ -1804,4 +1804,14 @@ object messages {
|refers to a subtype of type ${"A"}.
|"""
}

case class ClassAndCompanionNameClash(cls: Symbol)(implicit ctx: Context)
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I would include the two symbols that clash: cls and other

extends Message(ClassAndCompanionNameClashID) {
val kind = "Syntax"
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Should be "Naming"

val msg = hl"Naming clash, ${cls.owner} and it's companion object defines $cls"
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I would say

val msg = hl"Name clash: both ${cls.owner} and its companion object defines ${cls.name}"

val explanation =
s"""It is not allowed to define a class or module with the same
|name inside a class and companion object.
"""
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Assuming that you have the two symbols that clash: cls and other

val explanation = {
  val kind = if (cls.owner.is(Trait)) "trait" else "class"

  hl"""|A $kind and its companion object cannot both define a ${"class"}, ${"trait"} or ${"object"} with the same name:
       |  - ${cls.owner} defines ${cls}
       |  - ${other.owner} defines ${other}"""
}

}
}
4 changes: 1 addition & 3 deletions compiler/src/dotty/tools/dotc/typer/RefChecks.scala
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Expand Up @@ -115,9 +115,7 @@ object RefChecks {
if (!(cls.owner is ModuleClass)) {
val other = cls.owner.linkedClass.info.decl(cls.name)
if (other.symbol.isClass)
ctx.error(s"name clash: ${cls.owner} defines $cls" + "\n" +
s"and its companion ${cls.owner.companionModule} also defines $other",
cls.pos)
ctx.error(ClassAndCompanionNameClash(cls))
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You forgot the position:

ctx.error(ClassAndCompanionNameClash(cls), cls.pos)

}

// Override checking ------------------------------------------------------------
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20 changes: 20 additions & 0 deletions compiler/test/dotty/tools/dotc/reporting/ErrorMessagesTests.scala
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Expand Up @@ -1038,4 +1038,24 @@ class ErrorMessagesTests extends ErrorMessagesTest {
val ExpectedTypeBoundOrEquals(found) :: Nil = messages
assertEquals(Tokens.IDENTIFIER, found)
}

@Test def classAndCompanionNameClash =
checkMessagesAfter("refchecks") {
"""
|class T {
| class G {}
|}
|object T {
| class G {}
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I would make it a trait, to make the test case more interesting

|}
""".stripMargin
}.expect { (ictx, messages) =>
implicit val ctx: Context = ictx

assertMessageCount(1, messages)
val ClassAndCompanionNameClash(symbol) :: Nil = messages

assertEquals("class T", symbol.owner.show)
assertEquals("class G", symbol.show)
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Assuming that you have the two symbols that clash cls and other:

val ClassAndCompanionNameClash(cls, other) :: Nil = messages

assertEquals("class G", cls.show)
assertEquals("trait G", other.show)
assertEquals("class T", cls.owner.show)
assertEquals("object T", other.owner.show)

}
}