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Convert "method has return statement; needs result type" to new error format with MissingReturnTypeWithReturnStatement #3094

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Merged
merged 3 commits into from
Sep 14, 2017
Merged

Convert "method has return statement; needs result type" to new error format with MissingReturnTypeWithReturnStatement #3094

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0988ffa
Convert "method has return statement; needs result type" to new error…
TheReturningVoid Sep 9, 2017
5cb0571
Corrected additions as per review comments
TheReturningVoid Sep 14, 2017
14772a8
Corrected additions as per 2nd review comments
TheReturningVoid Sep 14, 2017
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1 change: 1 addition & 0 deletions compiler/src/dotty/tools/dotc/reporting/diagnostic/ErrorMessageID.java
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Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,7 @@ public enum ErrorMessageID {
WrongNumberOfParametersID,
DuplicatePrivateProtectedQualifierID,
ExpectedStartOfTopLevelDefinitionID,
MissingReturnTypeWithReturnStatementID,
;

public int errorNumber() {
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11 changes: 11 additions & 0 deletions compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
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Expand Up @@ -598,6 +598,17 @@ object messages {
|}"""
}

case class MissingReturnTypeWithReturnStatement(method: Symbol)(implicit ctx: Context)
extends Message(MissingReturnTypeWithReturnStatementID) {
val kind = "Syntax"
val msg = hl"$method has a return statement; it needs a result type"
val explanation =
hl"""|If a method contains a ${"return"} statement, it must have an
|explicit return type. For example:
|
|${"def good: Int /* explicit return type */ = return 1"}"""
}

case class YieldOrDoExpectedInForComprehension()(implicit ctx: Context)
extends Message(YieldOrDoExpectedInForComprehensionID) {
val kind = "Syntax"
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/typer/Typer.scala
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Expand Up @@ -987,7 +987,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
if (owner.isInlineMethod)
(EmptyTree, errorType(em"no explicit return allowed from inline $owner", tree.pos))
else if (!owner.isCompleted)
(EmptyTree, errorType(em"$owner has return statement; needs result type", tree.pos))
(EmptyTree, errorType(MissingReturnTypeWithReturnStatement(owner), tree.pos))
else {
val from = Ident(TermRef(NoPrefix, owner.asTerm))
val proto = returnProto(owner, cx.scope)
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13 changes: 13 additions & 0 deletions compiler/test/dotty/tools/dotc/reporting/ErrorMessagesTests.scala
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Expand Up @@ -955,4 +955,17 @@ class ErrorMessagesTests extends ErrorMessagesTest {

assertEquals(ExpectedStartOfTopLevelDefinition(), err)
}

@Test def missingReturnTypeWithReturnStatement =
checkMessagesAfter("frontend") {
"""class BadFunction {
| def bad() = { return "fail" }
|}
""".stripMargin
}.expect { (ictx, messages) =>
assertMessageCount(1, messages)

val MissingReturnTypeWithReturnStatement(method) :: Nil = messages
assertEquals(method.show, "bad")
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Should be method.name.show

}
}