Properly compile null in function contexts (#922)

Author: dcodeIO

src/compiler.ts

@@ -7107,12 +7107,20 @@ export class Compiler extends DiagnosticEmitter {
     switch (expression.kind) {
       case NodeKind.NULL: {
         let options = this.options;
-        let classReference = contextualType.classReference;
-        if (contextualType.is(TypeFlags.REFERENCE) && classReference !== null) {
-          this.currentType = classReference.type.asNullable();
-        } else {
-          this.currentType = options.usizeType; // TODO: anyref context yields <usize>0
+        if (contextualType.is(TypeFlags.REFERENCE)) {
+          let classReference = contextualType.classReference;
+          if (classReference) {
+            this.currentType = classReference.type.asNullable();
+            return options.isWasm64 ? module.i64(0) : module.i32(0);
+          }
+          let signatureReference = contextualType.signatureReference;
+          if (signatureReference) {
+            this.currentType = signatureReference.type.asNullable();
+            return module.i32(0);
+          }
+          // TODO: anyref context yields <usize>0
         }
+        this.currentType = options.usizeType;
         return options.isWasm64
           ? module.i64(0)
           : module.i32(0);

tests/compiler/function-expression.optimized.wat

@@ -7,8 +7,8 @@
  (import "env" "abort" (func $~lib/builtins/abort (param i32 i32 i32 i32)))
  (memory $0 1)
  (data (i32.const 8) ",\00\00\00\01\00\00\00\01\00\00\00,\00\00\00f\00u\00n\00c\00t\00i\00o\00n\00-\00e\00x\00p\00r\00e\00s\00s\00i\00o\00n\00.\00t\00s")
- (table $0 11 funcref)
- (elem (i32.const 0) $start:function-expression~someName $start:function-expression~anonymous|0 $start:function-expression~anonymous|0 $start:function-expression~someName $start:function-expression~anonymous|2 $start:function-expression~anonymous|3 $start:function-expression~anonymous|4 $start:function-expression~anonymous|5 $start:function-expression~anonymous|3 $start:function-expression~anonymous|4 $start:function-expression~anonymous|5)
+ (table $0 12 funcref)
+ (elem (i32.const 0) $start:function-expression~someName $start:function-expression~anonymous|0 $start:function-expression~anonymous|0 $start:function-expression~someName $start:function-expression~anonymous|2 $start:function-expression~anonymous|3 $start:function-expression~anonymous|4 $start:function-expression~anonymous|5 $start:function-expression~anonymous|3 $start:function-expression~anonymous|4 $start:function-expression~anonymous|5 $start:function-expression~anonymous|2)
  (global $~lib/argc (mut i32) (i32.const 0))
  (export "memory" (memory $0))
  (start $start)

tests/compiler/function-expression.ts

@@ -34,3 +34,12 @@ function testOmittedReturn3(): (a: i32, b: i32) => i32 {
 assert(testOmittedReturn1()(1, 2) == 3);
 assert(testOmittedReturn2()(1, 2) == 1);
 assert(testOmittedReturn3()(1, 2) == 42);
+
+function testNullable(b: boolean): (() => i32) | null {
+  if (b) {
+    return (): i32 => 1;
+  } else {
+    return null;
+  }
+}
+assert(testNullable(false) == null);

tests/compiler/function-expression.untouched.wat

@@ -7,8 +7,8 @@
  (import "env" "abort" (func $~lib/builtins/abort (param i32 i32 i32 i32)))
  (memory $0 1)
  (data (i32.const 8) ",\00\00\00\01\00\00\00\01\00\00\00,\00\00\00f\00u\00n\00c\00t\00i\00o\00n\00-\00e\00x\00p\00r\00e\00s\00s\00i\00o\00n\00.\00t\00s\00")
- (table $0 11 funcref)
- (elem (i32.const 0) $null $start:function-expression~anonymous|0 $start:function-expression~anonymous|1 $start:function-expression~someName $start:function-expression~anonymous|2 $start:function-expression~anonymous|3 $start:function-expression~anonymous|4 $start:function-expression~anonymous|5 $function-expression/testOmittedReturn1~anonymous|0 $function-expression/testOmittedReturn2~anonymous|0 $function-expression/testOmittedReturn3~anonymous|0)
+ (table $0 12 funcref)
+ (elem (i32.const 0) $null $start:function-expression~anonymous|0 $start:function-expression~anonymous|1 $start:function-expression~someName $start:function-expression~anonymous|2 $start:function-expression~anonymous|3 $start:function-expression~anonymous|4 $start:function-expression~anonymous|5 $function-expression/testOmittedReturn1~anonymous|0 $function-expression/testOmittedReturn2~anonymous|0 $function-expression/testOmittedReturn3~anonymous|0 $function-expression/testNullable~anonymous|0)
  (global $function-expression/f1 (mut i32) (i32.const 1))
  (global $~lib/argc (mut i32) (i32.const 0))
  (global $function-expression/f2 (mut i32) (i32.const 2))
@@ -67,7 +67,21 @@
  (func $function-expression/testOmittedReturn3 (; 14 ;) (type $FUNCSIG$i) (result i32)
   i32.const 10
  )
- (func $start:function-expression (; 15 ;) (type $FUNCSIG$v)
+ (func $function-expression/testNullable~anonymous|0 (; 15 ;) (type $FUNCSIG$i) (result i32)
+  i32.const 1
+ )
+ (func $function-expression/testNullable (; 16 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
+  local.get $0
+  if
+   i32.const 11
+   return
+  else
+   i32.const 0
+   return
+  end
+  unreachable
+ )
+ (func $start:function-expression (; 17 ;) (type $FUNCSIG$v)
   i32.const 1
   global.set $~lib/argc
   i32.const 1
@@ -209,10 +223,23 @@
    call $~lib/builtins/abort
    unreachable
   end
+  i32.const 0
+  call $function-expression/testNullable
+  i32.const 0
+  i32.eq
+  i32.eqz
+  if
+   i32.const 0
+   i32.const 24
+   i32.const 45
+   i32.const 0
+   call $~lib/builtins/abort
+   unreachable
+  end
  )
- (func $start (; 16 ;) (type $FUNCSIG$v)
+ (func $start (; 18 ;) (type $FUNCSIG$v)
   call $start:function-expression
  )
- (func $null (; 17 ;) (type $FUNCSIG$v)
+ (func $null (; 19 ;) (type $FUNCSIG$v)
  )
 )