fix: Disallow expressions with void type & references for some operations (#2474)

Author: MaxGraey

src/builtins.ts

@@ -2286,12 +2286,23 @@ function builtin_load(ctx: BuiltinContext): ExpressionRef {
   var typeArguments = ctx.typeArguments;
   var contextualType = ctx.contextualType;
   var type = typeArguments![0];
+
   var outType = (
     contextualType != Type.auto &&
     type.isIntegerValue &&
     contextualType.isIntegerValue &&
     contextualType.size > type.size
   ) ? contextualType : type;
+
+  if (!outType.isMemory) {
+    compiler.error(
+      DiagnosticCode.Operation_0_cannot_be_applied_to_type_1,
+      ctx.reportNode.typeArgumentsRange, "load", outType.toString()
+    );
+    compiler.currentType = Type.void;
+    return module.unreachable();
+  }
+
   var arg0 = compiler.compileExpression(operands[0], compiler.options.usizeType, Constraints.CONV_IMPLICIT);
   var numOperands = operands.length;
   var immOffset = 0;
@@ -2350,6 +2361,14 @@ function builtin_store(ctx: BuiltinContext): ExpressionRef {
           : Constraints.CONV_IMPLICIT
       );
   var inType = compiler.currentType;
+  if (!inType.isMemory) {
+    compiler.error(
+      DiagnosticCode.Operation_0_cannot_be_applied_to_type_1,
+      ctx.reportNode.typeArgumentsRange, "store", inType.toString()
+    );
+    compiler.currentType = Type.void;
+    return module.unreachable();
+  }
   if (
     type.isIntegerValue &&
     (

src/compiler.ts

@@ -10094,10 +10094,13 @@ export class Compiler extends DiagnosticEmitter {
         // Needs to be true (i.e. not zero) when the ref is _not_ null,
         // which means `ref.is_null` returns false (i.e. zero).
         return module.unary(UnaryOp.EqzI32, module.ref_is_null(expr));
-
       }
+      case TypeKind.VOID:
       default: {
-        assert(false);
+        this.error(
+          DiagnosticCode.An_expression_of_type_0_cannot_be_tested_for_truthiness,
+          reportNode.range, type.toString()
+        );
         return module.i32(0);
       }
     }

src/diagnosticMessages.json

@@ -120,6 +120,7 @@
   "A class may only extend another class.": 1311,
   "A parameter property cannot be declared using a rest parameter.": 1317,
   "A default export can only be used in a module.": 1319,
+  "An expression of type '{0}' cannot be tested for truthiness.": 1345,
   "An identifier or keyword cannot immediately follow a numeric literal.": 1351,
 
   "Duplicate identifier '{0}'.": 2300,

src/types.ts

@@ -323,6 +323,26 @@ export class Type {
     return classReference != null && classReference.hasDecorator(DecoratorFlags.UNMANAGED);
   }
 
+  get isMemory(): bool {
+    switch (this.kind) {
+      case TypeKind.BOOL:
+      case TypeKind.I8:
+      case TypeKind.I16:
+      case TypeKind.I32:
+      case TypeKind.I64:
+      case TypeKind.ISIZE:
+      case TypeKind.U8:
+      case TypeKind.U16:
+      case TypeKind.U32:
+      case TypeKind.U64:
+      case TypeKind.USIZE:
+      case TypeKind.F32:
+      case TypeKind.F64:
+      case TypeKind.V128: return true;
+    }
+    return false;
+  }
+
   /** Gets the corresponding non-nullable type. */
   get nonNullableType(): Type {
     if (this.isExternalReference) {

tests/compiler/issues/2473.json

@@ -0,0 +1,14 @@
+{
+  "asc_flags": [
+  ],
+  "stderr": [
+    "TS1345: An expression of type 'void' cannot be tested for truthiness.",
+    "TS1345: An expression of type 'void' cannot be tested for truthiness.",
+    "TS1345: An expression of type 'void' cannot be tested for truthiness.",
+    "AS203: Operation 'store' cannot be applied to type 'void'.",
+    "AS203: Operation 'load' cannot be applied to type 'void'.",
+    "AS203: Operation 'load' cannot be applied to type 'externref'.",
+    "AS203: Operation 'load' cannot be applied to type 'anyref'",
+    "EOF"
+  ]
+}

tests/compiler/issues/2473.ts

@@ -0,0 +1,17 @@
+const voidFn = (): void => {};
+
+// TS1345: An expression of type 'void' cannot be tested for truthiness.
+voidFn() ? 1 : 0;
+
+// TS1345: An expression of type 'void' cannot be tested for truthiness.
+if (voidFn()) {}
+
+// TS1345: An expression of type 'void' cannot be tested for truthiness.
+!voidFn();
+
+store<void>(8, voidFn());
+load<void>(8);
+load<externref>(8);
+load<anyref>(8);
+
+ERROR("EOF");