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feat: add NonNullable builtin type to remove null from type union #1875

Merged
merged 19 commits into from
Jun 8, 2021
Merged

feat: add NonNullable builtin type to remove null from type union #1875

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8aa0114
feat: add NonNullable builtin type to remove null from T
May 29, 2021
9851d6c
fix: linting
May 29, 2021
f5a6c31
Update src/resolver.ts
May 29, 2021
fac3fec
fix: update deps locally and finish renaming refactor
May 29, 2021
9810f2f
nit: simplify test
Jun 1, 2021
9198cf0
fix: remove old test generated by accident with --create
Jun 1, 2021
e9e85ae
fix: remove old artifacts from git cache
Jun 1, 2021
7896091
fix: rename again
Jun 1, 2021
706894c
feat: add second function to show casting works
Jun 1, 2021
a813892
Update src/resolver.ts
Jun 7, 2021
f9790bb
nit: refactor ensureOneTypeArgument
Jun 7, 2021
c6a7092
fix: make `!= 1`
Jun 7, 2021
a5cb27b
fix: remove one check
Jun 7, 2021
44d7b67
chore: rename internally `nonnull` and make an alias for `NonNullable`
Jun 7, 2021
3142241
fix: revert package-lock.json
Jun 7, 2021
510d52e
fix: revert nullable test
Jun 7, 2021
a715785
fix: add line at end of file
Jun 7, 2021
4411373
fix: add new line to test file
Jun 7, 2021
a44bf8f
chore: add newline to end of files that are missing one
Jun 8, 2021
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40 changes: 30 additions & 10 deletions package-lock.json
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1 change: 1 addition & 0 deletions src/common.ts
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Expand Up @@ -147,6 +147,7 @@ export namespace CommonNames {
export const indexof = "indexof";
export const valueof = "valueof";
export const returnof = "returnof";
export const notnullable = "NonNullable";
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// aliases
export const null_ = "null";
export const true_ = "true";
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6 changes: 6 additions & 0 deletions src/program.ts
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Expand Up @@ -992,6 +992,12 @@ export class Program extends DiagnosticEmitter {
this.makeNativeTypeDeclaration(CommonNames.returnof, CommonFlags.EXPORT | CommonFlags.GENERIC),
DecoratorFlags.BUILTIN
));
this.nativeFile.add(CommonNames.notnullable, new TypeDefinition(
CommonNames.notnullable,
this.nativeFile,
this.makeNativeTypeDeclaration(CommonNames.notnullable, CommonFlags.EXPORT | CommonFlags.GENERIC),
DecoratorFlags.BUILTIN
));

// The following types might not be enabled by compiler options, so the
// compiler needs to check this condition whenever such a value is created
Expand Down
111 changes: 55 additions & 56 deletions src/resolver.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -296,6 +296,7 @@ export class Resolver extends DiagnosticEmitter {
if (text == CommonNames.indexof) return this.resolveBuiltinIndexofType(node, ctxElement, ctxTypes, reportMode);
if (text == CommonNames.valueof) return this.resolveBuiltinValueofType(node, ctxElement, ctxTypes, reportMode);
if (text == CommonNames.returnof) return this.resolveBuiltinReturnTypeType(node, ctxElement, ctxTypes, reportMode);
if (text == CommonNames.notnullable) return this.resolveBuiltinNotNullableType(node, ctxElement, ctxTypes, reportMode);
}

// Resolve normally
Expand Down Expand Up @@ -438,19 +439,9 @@ export class Resolver extends DiagnosticEmitter {
/** How to proceed with eventual diagnostics. */
reportMode: ReportMode = ReportMode.REPORT
): Type | null {
var typeArgumentNodes = node.typeArguments;
if (!typeArgumentNodes || typeArgumentNodes.length != 1) {
if (reportMode == ReportMode.REPORT) {
let numTypeArguments = 0;
if (typeArgumentNodes) numTypeArguments = typeArgumentNodes.length;
this.error(
DiagnosticCode.Expected_0_type_arguments_but_got_1,
node.range, "1", numTypeArguments.toString()
);
}
return null;
}
var typeArgument = this.resolveType(typeArgumentNodes[0], ctxElement, ctxTypes, reportMode);
const typeArgumentNode = this.ensureOneTypeArgument(node, reportMode);
if (!typeArgumentNode) return null;
var typeArgument = this.resolveType(typeArgumentNode, ctxElement, ctxTypes, reportMode);
if (!typeArgument) return null;
switch (typeArgument.kind) {
case TypeKind.I8:
Expand Down Expand Up @@ -483,26 +474,16 @@ export class Resolver extends DiagnosticEmitter {
/** How to proceed with eventual diagnostics. */
reportMode: ReportMode = ReportMode.REPORT
): Type | null {
var typeArgumentNodes = node.typeArguments;
if (!typeArgumentNodes || typeArgumentNodes.length != 1) {
if (reportMode == ReportMode.REPORT) {
let numTypeArguments = 0;
if (typeArgumentNodes) numTypeArguments = typeArgumentNodes.length;
this.error(
DiagnosticCode.Expected_0_type_arguments_but_got_1,
node.range, "1", numTypeArguments.toString()
);
}
return null;
}
var typeArgument = this.resolveType(typeArgumentNodes[0], ctxElement, ctxTypes, reportMode);
const typeArgumentNode = this.ensureOneTypeArgument(node, reportMode);
if (!typeArgumentNode) return null;
var typeArgument = this.resolveType(typeArgumentNode, ctxElement, ctxTypes, reportMode);
if (!typeArgument) return null;
var classReference = typeArgument.classReference;
if (!classReference) {
if (reportMode == ReportMode.REPORT) {
this.error(
DiagnosticCode.Index_signature_is_missing_in_type_0,
typeArgumentNodes[0].range, typeArgument.toString()
typeArgumentNode.range, typeArgument.toString()
);
}
return null;
Expand All @@ -520,7 +501,7 @@ export class Resolver extends DiagnosticEmitter {
if (reportMode == ReportMode.REPORT) {
this.error(
DiagnosticCode.Index_signature_is_missing_in_type_0,
typeArgumentNodes[0].range, typeArgument.toString()
typeArgumentNode.range, typeArgument.toString()
);
}
return null;
Expand All @@ -536,19 +517,9 @@ export class Resolver extends DiagnosticEmitter {
/** How to proceed with eventual diagnostics. */
reportMode: ReportMode = ReportMode.REPORT
): Type | null {
var typeArgumentNodes = node.typeArguments;
if (!typeArgumentNodes || typeArgumentNodes.length != 1) {
let numTypeArguments = 0;
if (typeArgumentNodes) numTypeArguments = typeArgumentNodes.length;
if (reportMode == ReportMode.REPORT) {
this.error(
DiagnosticCode.Expected_0_type_arguments_but_got_1,
node.range, "1", numTypeArguments.toString()
);
}
return null;
}
var typeArgument = this.resolveType(typeArgumentNodes[0], ctxElement, ctxTypes, reportMode);
const typeArgumentNode = this.ensureOneTypeArgument(node, reportMode);
if (!typeArgumentNode) return null;
var typeArgument = this.resolveType(typeArgumentNode, ctxElement, ctxTypes, reportMode);
if (!typeArgument) return null;
var classReference = typeArgument.getClassOrWrapper(this.program);
if (classReference) {
Expand All @@ -558,7 +529,7 @@ export class Resolver extends DiagnosticEmitter {
if (reportMode == ReportMode.REPORT) {
this.error(
DiagnosticCode.Index_signature_is_missing_in_type_0,
typeArgumentNodes[0].range, typeArgument.toString()
typeArgumentNode.range, typeArgument.toString()
);
}
return null;
Expand All @@ -574,31 +545,39 @@ export class Resolver extends DiagnosticEmitter {
/** How to proceed with eventualy diagnostics. */
reportMode: ReportMode = ReportMode.REPORT
): Type | null {
var typeArgumentNodes = node.typeArguments;
if (!typeArgumentNodes || typeArgumentNodes.length != 1) {
if (reportMode == ReportMode.REPORT) {
let numTypeArguments = 0;
if (typeArgumentNodes) numTypeArguments = typeArgumentNodes.length;
this.error(
DiagnosticCode.Expected_0_type_arguments_but_got_1,
node.range, "1", numTypeArguments.toString()
);
}
return null;
}
var typeArgument = this.resolveType(typeArgumentNodes[0], ctxElement, ctxTypes, reportMode);
const typeArgumentNode = this.ensureOneTypeArgument(node, reportMode);
if (!typeArgumentNode) return null;
var typeArgument = this.resolveType(typeArgumentNode, ctxElement, ctxTypes, reportMode);
if (!typeArgument) return null;
var signatureReference = typeArgument.getSignature();
if (signatureReference) return signatureReference.returnType;
if (reportMode == ReportMode.REPORT) {
this.error(
DiagnosticCode.Type_0_has_no_call_signatures,
typeArgumentNodes[0].range, typeArgument.toString()
typeArgumentNode.range, typeArgument.toString()
);
}
return null;
}

private resolveBuiltinNotNullableType(
/** The type to resolve. */
node: NamedTypeNode,
/** Contextual element. */
ctxElement: Element,
/** Contextual types, i.e. `T`. */
ctxTypes: Map<string,Type> | null = null,
/** How to proceed with eventual diagnostics. */
reportMode: ReportMode = ReportMode.REPORT
): Type | null {
const typeArgumentNode = this.ensureOneTypeArgument(node, reportMode);
if (!typeArgumentNode) return null;
var typeArgument = this.resolveType(typeArgumentNode, ctxElement, ctxTypes, reportMode);
if (!typeArgument) return null;
if (!typeArgument.isNullableReference) return typeArgument;
return typeArgument.nonNullableType;
}

/** Resolves a type name to the program element it refers to. */
resolveTypeName(
/** The type name to resolve. */
Expand Down Expand Up @@ -3362,4 +3341,24 @@ export class Resolver extends DiagnosticEmitter {
}
return instance;
}

private ensureOneTypeArgument(
/** The type to resolve. */
node: NamedTypeNode,
/** How to proceed with eventual diagnostics. */
reportMode: ReportMode = ReportMode.REPORT): TypeNode | null {
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var typeArgumentNodes = node.typeArguments;
if (!typeArgumentNodes || typeArgumentNodes.length != 1) {
let numTypeArguments = 0;
if (typeArgumentNodes) numTypeArguments = typeArgumentNodes.length;
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if (reportMode == ReportMode.REPORT) {
this.error(
DiagnosticCode.Expected_0_type_arguments_but_got_1,
node.range, "1", numTypeArguments.toString()
);
}
return null;
}
return typeArgumentNodes[0];
}
}
2 changes: 2 additions & 0 deletions std/assembly/index.d.ts
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Expand Up @@ -1314,6 +1314,8 @@ declare type valueof<T extends unknown[]> = T[0];
declare type ReturnType<T extends (...args: any) => any> = T extends (...args: any) => infer R ? R : any;
/** A special type evaluated to the return type of T if T is a callable function. */
declare type returnof<T extends (...args: any) => any> = ReturnType<T>;
/** A special type that excludes null and undefined from T. */
declare type NonNullable<T> = T extends null | undefined ? never : T;
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Wait, how does this work?

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Heh, toyed around with it a little and it works, I just don't understand how

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@willemneal willemneal Jun 8, 2021 •
edited

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It's a conditional type. NonNullable<null> becomes the never type which would cause it to fail to typecheck. We don't have this issue because it's not possible to type something as null, see here

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My guess is that this somehow decomposes string | null (which extends null I guess?) to string and null, with the null turned into never, so that the outcome would be string | never with the never being dropped or something.


/** Pseudo-class representing the backing class of integer types. */
declare class _Integer {
Expand Down