Little bug in "Writing A Compiler In Go" 1.0

01_vm_test.go

func TestCallingRecursiveFunctionsInFunctions(t *testing.T) {
	tests := []vmTestCase{
		{
			// This works
			input: `
		let inner = fn(x) {
			if (x == 0) {
				return 0;
			} else {
				inner(x - 1);
			}
		};
		inner(1);
		`,
			expected: 0,
		},
		{
			// This also works
			input: `
		let inner = fn(x) {
			if (x == 0) {
				return 0;
			} else {
				inner(x - 1);
			}
		};
		let wrapper = fn() {
			inner(1);
		};
		wrapper();
		`,
			expected: 0,
		},
		{
			// This does _NOT_ work
			input: `
		let wrapper = fn() {
			let inner = fn(x) {
				if (x == 0) {
					return 0;
				} else {
					inner(x - 1);
				}
			};
			inner(1);
		};
		wrapper();
		`,
			expected: 0,
		},
	}

	runVmTests(t, tests)
}

02_bytecode_constants_dump.txt

This is a compiler/constant-pool dump from the third test case:

CONSTANT 0 0xc00009a158 (*object.Integer):
 Value: 0

CONSTANT 1 0xc00009a168 (*object.Integer):
 Value: 0

CONSTANT 2 0xc00009a190 (*object.Integer):
 Value: 1

CONSTANT 3 0xc000078e40 (*object.CompiledFunction):
 Instructions:
0000 OpGetLocal 0
0002 OpConstant 0
0005 OpEqual
0006 OpJumpNotTruthy 16
0009 OpConstant 1
0012 OpReturnValue
0013 OpJump 26
0016 OpGetFree 0
0018 OpGetLocal 0
0020 OpConstant 2
0023 OpSub
0024 OpCall 1
0026 OpReturnValue

CONSTANT 4 0xc00009a1b8 (*object.Integer):
 Value: 1

CONSTANT 5 0xc000078e70 (*object.CompiledFunction):
 Instructions:
0000 OpGetLocal 0
0002 OpClosure 3 1
0006 OpSetLocal 0
0008 OpGetLocal 0
0010 OpConstant 4
0013 OpCall 1
0015 OpReturnValue

main:
0000 OpClosure 5 0
0004 OpSetGlobal 0
0007 OpGetGlobal 0
0010 OpCall 0
0012 OpPop

03_vm_trace.txt

This is VM trace of the third test case.

FRAME INS  OP            ARG    ARG       SP  STACK
[01] 0000 OpClosure        5     0      sp= 1 stack=[ Closure[0xc00000a900] ]
[01] 0004 OpSetGlobal            0      sp=0 stack=[]
[01] 0007 OpGetGlobal            0      sp= 1 stack=[ Closure[0xc00000a900] ]
[01] 0010 OpCall                 0      sp= 2 stack=[ Closure[0xc00000a900] | <nil> ]
[02] 0000 OpGetLocal             0      sp= 3 stack=[ Closure[0xc00000a900] | <nil> | <nil> ]
[02] 0002 OpClosure        3     1      sp= 3 stack=[ Closure[0xc00000a900] | <nil> | Closure[0xc00000a980] ]
[02] 0006 OpSetLocal             0      sp= 2 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] ]
[02] 0008 OpGetLocal             0      sp= 3 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] ]
[02] 0010 OpConstant             4      sp= 4 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 ]
[02] 0013 OpCall                 1      sp= 4 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 ]
[03] 0000 OpGetLocal             0      sp= 5 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 | 1 ]
[03] 0002 OpConstant             0      sp= 6 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 | 1 | 0 ]
[03] 0005 OpEqual                       sp= 5 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 | false ]
[03] 0006 OpJumpNotTruthy          16   sp= 4 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 ]
[03] 0016 OpGetFree              0      sp= 5 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 | <nil> ]
[03] 0018 OpGetLocal             0      sp= 6 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 | <nil> | 1 ]
[03] 0020 OpConstant             2      sp= 7 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 | <nil> | 1 | 1 ]
[03] 0023 OpSub                         sp= 6 stack=[ Closure[0xc00000a900] | Closure[0xc00000a980] | Closure[0xc00000a980] | 1 | <nil> | 0 ]
[03] 0024 OpCall                 1--- FAIL: TestCallingRecursiveFunctionsInFunctions (0.00s)
    vm_test.go:644: vm error: calling non-closure and non-builtin
FAIL
FAIL    github.com/mrnugget/monkey/vm   0.005s