more helpful error messages

compiler/src/prog8/compiler/astprocessing/AstChecker.kt

@@ -585,14 +585,22 @@ internal class AstChecker(private val program: Program,
             checkMultiAssignment(assignment, fcall, fcallTarget)
         } else if(fcallTarget!=null) {
             if(fcallTarget.returntypes.size!=1) {
-                errors.err("number of assignment targets doesn't match number of return values from the subroutine", fcall.position)
-                return
+                return numberOfReturnValuesError(1, fcallTarget.returntypes, fcall.position)
             }
         }
 
         super.visit(assignment)
     }
 
+    private fun numberOfReturnValuesError(actual: Int, expectedTypes: List<DataType>, position: Position) {
+        if(actual<expectedTypes.size) {
+            val missing = expectedTypes.drop(actual).joinToString(", ")
+            errors.err("some return values are not assigned: expected ${expectedTypes.size} got $actual, missing assignments for: $missing", position)
+        }
+        else
+            errors.err("too many return values are assigned: expected ${expectedTypes.size} got $actual", position)
+    }
+
     private fun checkMultiAssignment(assignment: Assignment, fcall: IFunctionCall?, fcallTarget: Subroutine?) {
         // multi-assign: check the number of assign targets vs. the number of return values of the subroutine
         // also check the types of the variables vs the types of each return value
@@ -602,8 +610,7 @@ internal class AstChecker(private val program: Program,
         }
         val targets = assignment.target.multi!!
         if(fcallTarget.returntypes.size!=targets.size) {
-            errors.err("number of assignment targets doesn't match number of return values from the subroutine", fcall.position)
-            return
+            return numberOfReturnValuesError(targets.size, fcallTarget.returntypes, fcall.position)
         }
         fcallTarget.returntypes.zip(targets).withIndex().forEach { (index, p) ->
             val (returnType, target) = p

compiler/src/prog8/compiler/astprocessing/AstIdentifiersChecker.kt

@@ -27,6 +27,15 @@ internal class AstIdentifiersChecker(private val errors: IErrorReporter,
         errors.warn("name '$name' shadows the definition at ${existing.position.file} line ${existing.position.line}", position)
     }
 
+    private fun invalidNumberOfArgsError(pos: Position, numArgs: Int, params: List<String>) {
+        if(numArgs<params.size) {
+            val missing = params.drop(numArgs).joinToString(", ")
+            errors.err("invalid number of arguments: expected ${params.size} got $numArgs, missing: $missing", pos)
+        }
+        else
+            errors.err("invalid number of arguments: expected ${params.size} got $numArgs", pos)
+    }
+
     override fun visit(block: Block) {
         val existing = blocks[block.name]
         if(existing!=null) {
@@ -166,7 +175,7 @@ internal class AstIdentifiersChecker(private val errors: IErrorReporter,
                 val expectedNumberOfArgs: Int = target.parameters.size
                 if(call.args.size != expectedNumberOfArgs) {
                     val pos = (if(call.args.any()) call.args[0] else (call as Node)).position
-                    errors.err("invalid number of arguments", pos)
+                    invalidNumberOfArgsError(pos, call.args.size, target.parameters.map { it.name })
                 }
             }
             is BuiltinFunctionPlaceholder -> {
@@ -174,7 +183,7 @@ internal class AstIdentifiersChecker(private val errors: IErrorReporter,
                 val expectedNumberOfArgs: Int = func.parameters.size
                 if(call.args.size != expectedNumberOfArgs) {
                     val pos = (if(call.args.any()) call.args[0] else (call as Node)).position
-                    errors.err("invalid number of arguments", pos)
+                    invalidNumberOfArgsError(pos, call.args.size, func.parameters.map {it.name })
                 }
                 if(target.name=="memory") {
                     val name = call.args[0] as? StringLiteral

docs/source/todo.rst

@@ -3,12 +3,6 @@ TODO
 
 Regenerate skeleton doc files.
 
-"invalid number of arguments" -> print the list of missing arguments
-
-callfar() should allow setting an argument in the X register as well?
-
-Add a new SublimeText syntax file for prog8, and also install this for bat: https://github.com/sharkdp/bat?tab=readme-ov-file#adding-new-syntaxes--language-definitions
-
 Improve register load order in subroutine call args assignments:
 in certain situations, the "wrong" order of evaluation of function call arguments is done which results
 in overwriting registers that already got their value, which requires a lot of stack juggling (especially on plain 6502 cpu!)
@@ -17,8 +11,9 @@ Maybe this routine can be made more intelligent.  See usesOtherRegistersWhileEva
 
 Future Things and Ideas
 ^^^^^^^^^^^^^^^^^^^^^^^
-Compiler:
 
+- Add a new SublimeText syntax file for prog8, and also install this for bat: https://github.com/sharkdp/bat?tab=readme-ov-file#adding-new-syntaxes--language-definitions
+- callfar() should allow setting an argument in the X register as well?
 - AST weirdness: why is call(...) a normal FunctionCallStatement and not a BuiltinFunctionCall?  What does ror() produce for instance?
 - Can we support signed % (remainder) somehow?
 - Don't add "random" rts to %asm blocks but instead give a warning about it? (but this breaks existing behavior that others already depend on... command line switch? block directive?)

examples/test.p8

@@ -1,48 +1,19 @@
 %import textio
-%import string
-%import compression
-%import test_stack
 %zeropage basicsafe
 %option no_sysinit
 
 main {
     sub start() {
-        test_stack.test()
+        cx16.r0L = returns3()
+        cx16.r0L, cx16.r1L, cx16.r2L, cx16.r3L = returns3()
+        txt.print_uwhex()
+        txt.print_uwhex(1, true, 2, 3)
+    }
 
-        txt.print_uwhex(cbm.CHROUT, true)
-        txt.print_uwhex(&cbm.CHROUT, true)
-        txt.nl()
-
-        cx16.r0 = &function1
-        callfar(0, $ffd2, $0031)
-        callfar(0, cbm.CHROUT, $000d)
-        callfar(0, function1, $6660)
-        callfar(0, cx16.r0, $ffff)
-        cx16.r0 -=10
-        callfar(0, cx16.r0+10, $eeee)
-
-        cx16.r0 = &function2
-        callfar(0, $ffd2, $0032)
-        callfar(0, cbm.CHROUT, $000d)
-        callfar(0, function2, $6660)
-        callfar(0, cx16.r0, $ffff)
-        cx16.r0 -=10
-        callfar(0, cx16.r0+10, $eeee)
-
-        test_stack.test()
-        cx16.r0++
-
-        sub function1(uword arg) {
-            txt.print("function 1 arg=")
-            txt.print_uwhex(arg, false)
-            txt.nl()
-        }
-
-        sub function2(uword arg) {
-            txt.print("function 2 arg=")
-            txt.print_uwhex(arg, false)
-            txt.nl()
-        }
+    asmsub returns3() -> ubyte @A, ubyte @X, bool @Pc {
+        %asm {{
+            rts
+        }}
     }
 }