supports undefined type and undefined values

microcontroller/core/include/c-runtime.h

@@ -87,7 +87,7 @@ inline value_t ptr_to_value(pointer_t v) { return (value_t)(((uintptr_t)v & 0xff
 inline bool is_ptr_value(value_t v) { return (v & 3) == 3; }
 
 #define VALUE_NULL    3         // null pointer: 0000 ... 0011
-#define VALUE_UNDEF   0
+#define VALUE_UNDEF   3         // equivalent to VALUE_NULL
 #define VALUE_ZERO    0         // integer 0
 #define VALUE_FZERO   1         // float 0.0
 #define VALUE_FALSE   0         // 0000 ... 0000 (integer 0)

server/src/transpiler/code-generator/c-runtime.ts

@@ -111,8 +111,10 @@ export function typeConversion(from: StaticType | undefined, to: StaticType | un
       else
         break
     case BooleanT:
-      if (from === Integer || from === Float)
+      if (from === Integer)
         return '('
+      else if (from === Float)
+        return '(int32_t)('
       else if (from === Any)
         return 'safe_value_to_bool('
       else

server/src/transpiler/code-generator/code-generator.ts

@@ -155,6 +155,11 @@ export class CodeGenerator extends visitor.NodeVisitor<VariableEnv> {
   }
 
   identifier(node: AST.Identifier, env: VariableEnv): void {
+    if (node.name === 'undefined') {
+      this.result.write('VALUE_UNDEF')
+      return
+    }
+
     const info = env.table.lookup(node.name)
     if (info !== undefined) {
         if (info.isFunction) {

server/src/transpiler/type-checker.ts

@@ -165,6 +165,11 @@ export default class TypeChecker<Info extends NameInfo> extends visitor.NodeVisi
   }
 
   identifier(node: AST.Identifier, names: NameTable<Info>): void {
+    if (node.name === 'undefined') {
+      this.result = Null
+      return
+    }
+
     const nameInfo = names.lookup(node.name)
     if (nameInfo !== undefined) {
       const info = nameInfo as NameInfo

server/src/transpiler/types.ts

@@ -119,6 +119,8 @@ export class ArrayType extends ObjectType {
 export function typeToString(type: StaticType): string {
   if (type instanceof CompositeType)
     return type.sourceName()
+  else if (type === Null)
+    return 'undefined'
   else
     return type
 }
@@ -161,7 +163,7 @@ export function isSubtype(subtype: StaticType, type: StaticType): boolean {
     || subtype === StringT && type === objectType)
     return true
   else if (type === BooleanT)
-    return subtype !== Void && subtype !== Any
+    return subtype === BooleanT
   else if (subtype instanceof CompositeType)
     return subtype.isSubtypeOf(type)
   else

server/tests/transpiler/code-generator/code-generator.test.ts

@@ -36,7 +36,7 @@ test('boolean conditions', () => {
       let c: any = 3
       while (c)
         if (c-- < 0)
-          b = null
+          b = true
         else if (c < -10) {
           let str: any = null
           let k = str + 1
@@ -70,10 +70,33 @@ test('boolean conditions', () => {
   expect(compileAndRun(src)).toEqual('')
 })
 
+test('wrong assignment to boolean', () => {
+  const src = `
+  let b = true
+  b = null
+  `
+
+  expect(() => { compileAndRun(src) }).toThrow(/assignable to type 'boolean'/)
+
+  const src2 = `
+  let b = true
+  b = 3
+  `
+
+  expect(() => { compileAndRun(src2) }).toThrow(/assignable to type 'boolean'/)
+
+  const src3 = `
+  let b = true
+  b = 'foo'
+  `
+
+  expect(() => { compileAndRun(src2) }).toThrow(/assignable to type 'boolean'/)
+})
+
 test('literals', () => {
   const src = `
   function foo(n: integer) {
-    const empty = null
+    const empty = null // or undefined
     const i = n
     const f = 7.4
     const b1 = true
@@ -89,12 +112,12 @@ test('literals', () => {
   }
   foo(33)
   `
-  expect(compileAndRun(src)).toBe('null\n33\n7.400000\n1\n0\ntest\n')
+  expect(compileAndRun(src)).toBe('undefined\n33\n7.400000\n1\n0\ntest\n')
 })
 
 test('undefined', () => {
   const src = 'const k = undefined'
-  expect(() => { compileAndRun(src) }).toThrow(/unknown name: undefined/)
+  compileAndRun(src)
 })
 
 test('control structuers', () => {
@@ -658,9 +681,10 @@ test('typeof operator', () => {
   print(typeof('foo'))
   print(typeof([1, 2, 3]))
   print(typeof(null))
+  print(typeof(undefined))
   print(typeof(foo))
   `
-  expect(compileAndRun(src)).toBe('integer\ninteger\nstring\ninteger[]\nnull\n(any) => any\n')
+  expect(compileAndRun(src)).toBe('integer\ninteger\nstring\ninteger[]\nundefined\nundefined\n(any) => any\n')
 })
 
 test('++/-- operator', () => {
@@ -828,7 +852,7 @@ test('any to null', () => {
   print(foo(null))
   `
 
-  expect(compileAndRun(src)).toBe('null\n')
+  expect(compileAndRun(src)).toBe('undefined\n')
 })
 
 test('null to any or string', () => {
@@ -847,7 +871,7 @@ test('null to any or string', () => {
   }
   `
 
-  expect(compileAndRun(src)).toBe('null\n')
+  expect(compileAndRun(src)).toBe('undefined\n')
   expect(() => compileAndRun(src2)).toThrow(/not assignable.*line 3/)
 })
 
@@ -954,7 +978,7 @@ test('function call', () => {
   print(baz(null, [1, 2], 11, 'baz2'))
   `
 
-  expect(compileAndRun(src)).toBe([7, 3, '7.400000', 'null', 1, 'baz2', 11].join('\n') + '\n')
+  expect(compileAndRun(src)).toBe([7, 3, '7.400000', 'undefined', 1, 'baz2', 11].join('\n') + '\n')
 })
 
 test('array access', () => {

server/tests/transpiler/code-generator/test-code-generator.ts

@@ -23,8 +23,8 @@ static void fbody_print(value_t self, value_t m) {
     printf("%d\\n", value_to_int(m));
   else if (is_float_value(m))
     printf("%f\\n", value_to_float(m));
-  else if (m == VALUE_NULL)
-    puts("null");
+  else if (m == VALUE_NULL || m == VALUE_UNDEF)
+    puts("undefined");
   else if (gc_is_string_literal(m))
     puts(gc_string_literal_cstr(m));
   else