I kind of forgot that indirect JSR needs a trampoline first :/

src/sixtypical/compiler.py

@@ -9,7 +9,7 @@ from sixtypical.model import (
 )
 from sixtypical.emitter import Byte, Label, Offset
 from sixtypical.gen6502 import (
-    Immediate, Absolute, AbsoluteX, AbsoluteY, Relative,
+    Immediate, Absolute, AbsoluteX, AbsoluteY, Indirect, Relative,
     LDA, LDX, LDY, STA, STX, STY,
     TAX, TAY, TXA, TYA,
     CLC, SEC, ADC, SBC, ROL, ROR,
@@ -193,8 +193,16 @@ class Compiler(object):
             else:
                 raise UnsupportedOpcodeError(instr)
         elif opcode == 'call':
+            location = instr.location
             label = self.labels[instr.location.name]
+            if isinstance(location.type, RoutineType):
                 self.emitter.emit(JSR(Absolute(label)))
+            elif isinstance(location.type, VectorType):
+                # XXX NOT QUITE RIGHT, IS IT?
+                # We need to simulate an indirect JSR!
+                self.emitter.emit(JMP(Indirect(label)))
+            else:
+                raise NotImplementedError
         elif opcode == 'if':
             cls = {
                 False: {

tests/SixtyPical Analysis.md

@@ -1119,3 +1119,32 @@ Routines are read-only.
     |     copy vec, foo
     | }
     ? TypeMismatchError
+
+Indirect call.
+
+    | vector foo outputs x trashes z, n
+    | 
+    | routine bar outputs x trashes z, n {
+    |     ld x, 200
+    | }
+    | 
+    | routine main inputs bar outputs x, foo trashes a, z, n {
+    |     copy bar, foo
+    |     call foo
+    | }
+    = ok
+
+Calling the vector has indeed trashed stuff etc,
+
+    | vector foo trashes x, z, n
+    | 
+    | routine bar trashes x, z, n {
+    |     ld x, 200
+    | }
+    | 
+    | routine main inputs bar outputs x, foo trashes z, n {
+    |     ld x, 0
+    |     copy bar, foo
+    |     call foo
+    | }
+    ? UninitializedOutputError: x

tests/SixtyPical Compilation.md

@@ -261,3 +261,17 @@ Copy instruction inside interrupts off block.
     |   }
     | }
     = 00c078ad0fc08d11c0ad10c08d12c05860e860
+
+Indirect call.
+
+    | vector foo outputs x trashes z, n
+    | 
+    | routine bar outputs x trashes z, n {
+    |     ld x, 200
+    | }
+    | 
+    | routine main inputs bar outputs x, foo trashes a, z, n {
+    |     copy bar, foo
+    |     call foo
+    | }
+    = 00c0

tests/SixtyPical Execution.md

@@ -409,7 +409,7 @@ Indirect call.
     |     ld x, 200
     | }
     | 
-    | routine main {
+    | routine main inputs bar outputs x, foo trashes a, z, n {
     |     copy bar, foo
     |     call foo
     | }