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tweaking subroutine return values

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This commit is contained in:
Irmen de Jong 2018-11-11 18:19:08 +01:00
parent 95b05d08b3
commit 4ade45f51f
3 changed files with 26 additions and 6 deletions
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12
compiler/examples/test.p8
View File

@ -7,7 +7,19 @@
sub start() {
ubyte derp
derp=foo()
derp=c64.GETADR()
return
}
sub foo() -> ubyte {
return 1 ; @todo not ubyte but byte (if sub returns byte)
}
}

3
compiler/src/prog8/ast/AST.kt
View File

@ -1380,7 +1380,7 @@ class FunctionCall(override var target: IdentifierReference,
return null // no return value
if(stmt.returntypes.size==1)
return stmt.returntypes[0]
return null // has multiple return types...
return null // has multiple return types... so not a single resulting datatype possible
}
is Label -> return null
}
@ -1447,6 +1447,7 @@ class AnonymousScope(override var statements: MutableList<IStatement>,
// the subroutine class covers both the normal user-defined subroutines,
// and also the predefined/ROM/register-based subroutines.
// (multiple return types can only occur for the latter type)
class Subroutine(override val name: String,
val parameters: List<SubroutineParameter>,
val returntypes: List<DataType>,

17
compiler/src/prog8/ast/AstChecker.kt
View File

@ -196,8 +196,9 @@ class AstChecker(private val namespace: INameScope,
super.process(subroutine)
// user-defined subroutines can only have zero or one return type
// (multiple return values are only allowed for asm subs)
if(!subroutine.isAsmSubroutine && subroutine.returntypes.size>1)
err("subroutine has more than one return value")
err("subroutines can only have one return value")
// subroutine must contain at least one 'return' or 'goto'
// (or if it has an asm block, that must contain a 'rts' or 'jmp')
@ -357,8 +358,15 @@ class AstChecker(private val namespace: INameScope,
} else {
val sourceDatatype: DataType? = assignment.value.resultingDatatype(namespace, heap)
if(sourceDatatype==null) {
if(assignment.value is FunctionCall)
checkResult.add(ExpressionError("function call doesn't return a suitable value to use in assignment", assignment.value.position))
if(assignment.value is FunctionCall) {
// a functioncall COULD return multiple values (from an asm subroutine), treat that differently
val stmt = (assignment.value as FunctionCall).target.targetStatement(namespace)
if(stmt is Subroutine && stmt.returntypes.size>1) {
checkResult.add(ExpressionError("subroutine returning multiple values", assignment.value.position)) // TODO check this
}
else
checkResult.add(ExpressionError("function call doesn't return a suitable value to use in assignment", assignment.value.position))
}
else
checkResult.add(ExpressionError("assignment value is invalid or has no proper datatype", assignment.value.position))
}
@ -633,8 +641,7 @@ class AstChecker(private val namespace: INameScope,
if(targetStatement!=null)
checkFunctionCall(targetStatement, functionCall.arglist, functionCall.position)
if(targetStatement is Subroutine && targetStatement.returntypes.isNotEmpty())
if(!targetStatement.isAsmSubroutine)
printWarning("result value of subroutine call is discarded", functionCall.position)
printWarning("result value of subroutine call is discarded", functionCall.position)
return super.process(functionCall)
}