fix generics

src/ast.ts

@@ -141,7 +141,7 @@ export type FunctionArg<P extends Phase> = {
 
 export type ItemKindType<P extends Phase> = {
   kind: "type";
-  generics: Ident[];
+  genericParams: Ident[];
   type: TypeDefKind<P>;
   ty?: Ty;
 };
@@ -417,7 +417,7 @@ export const UNARY_KINDS: UnaryKind[] = ["!", "-"];
 export type TypeKind<P extends Phase> =
   | {
       kind: "ident";
-      generics: Type<P>[];
+      genericArgs: Type<P>[];
       value: IdentWithRes<P>;
     }
   | {
@@ -793,7 +793,7 @@ export function superFoldType<From extends Phase, To extends Phase>(
     case "ident": {
       return {
         kind: "ident",
-        generics: type.generics.map((type) => folder.type(type)),
+        genericArgs: type.genericArgs.map((type) => folder.type(type)),
         value: folder.ident(type.value),
         span,
       };

src/codegen.test.ts

@@ -7,7 +7,6 @@ it("should compute struct layout correctly", () => {
     kind: "struct",
     itemId: ItemId.dummy(),
     genericArgs: [],
-    params: [],
     _name: "",
     fields_no_subst: [
       ["uwu", TYS.I32],
@@ -54,7 +53,6 @@ it("should compute single field struct layout correctly", () => {
     kind: "struct",
     itemId: ItemId.dummy(),
     genericArgs: [],
-    params: [],
     _name: "",
     fields_no_subst: [["owo", TYS.INT]],
   };

src/codegen.ts

@@ -384,8 +384,7 @@ function lowerFunc(cx: Context, func: ItemFunction<Typecked>) {
     fcx.wasm.body = body.instructions;
   } else {
     lowerExpr(fcx, wasmFunc.body, body);
-
-    paramLocations.forEach((local) => {
+    paramLocations.forEach((local) => {     
       const refcount = needsRefcount(local.ty);
       if (refcount !== undefined) {
         // TODO: correctly deal with tuples
@@ -1264,7 +1263,6 @@ function argRetAbi(param: Ty): ArgRetAbi {
       return [];
     case "var":
     case "param":
-    case "alias":
     case "error":
       codegenUnreachableTy(param);
   }
@@ -1320,7 +1318,6 @@ function wasmTypeForBody(ty: Ty): wasm.ValType[] {
       return [];
     case "var":
     case "param":
-    case "alias":
     case "error":
       codegenUnreachableTy(ty);
   }

src/parser.ts

@@ -173,7 +173,7 @@ function parseItem(t: State): [State, Item<Parsed>] {
       {
         kind: "type",
         name: name.ident,
-        generics,
+        genericParams: generics,
         type,
         span: name.span,
         id: ItemId.dummy(),
@@ -694,7 +694,7 @@ function parseType(t: State): [State, Type<Parsed>] {
         t,
         {
           kind: "ident",
-          generics,
+          genericArgs: generics,
           value: { name: tok.ident, span },
           span,
         },

src/printer.ts

@@ -65,9 +65,9 @@ function printFunction(func: ItemFunction<AnyPhase>): string {
 
 function printTypeDef(type: ItemType<AnyPhase>): string {
   const head = `type ${type.name}${
-    type.generics.length === 0
+    type.genericParams.length === 0
       ? ""
-      : `[${type.generics.map((ident) => ident.name).join(", ")}]`
+      : `[${type.genericParams.map((ident) => ident.name).join(", ")}]`
   } = `;
   switch (type.type.kind) {
     case "struct": {
@@ -284,8 +284,6 @@ export function printTy(ty: Ty): string {
       return "!";
     case "param":
       return ty.name;
-    case "alias":
-      return printTy(substituteTy(ty.genericArgs, ty.actual));
     case "error":
       return "<ERROR>";
   }

src/resolve.ts

@@ -225,7 +225,7 @@ function resolveModule(
           };
         }
         case "type": {
-          tyParamScopes = item.generics.map(({ name }) => name);
+          tyParamScopes = item.genericParams.map(({ name }) => name);
 
           const type = { ...superFoldItem(item, this) };
 

src/typeck/expr.ts

@@ -10,7 +10,6 @@ import {
   Folder,
   LOGICAL_KINDS,
   LoopId,
-  Resolution,
   Resolved,
   StructLiteralField,
   Type,
@@ -91,7 +90,6 @@ export function checkBody(
   fnTy: TyFn,
 ): Expr<Typecked> {
   const infcx = new InferContext(cx.gcx.error);
-
   const fcx: FuncCtx = {
     cx,
     infcx,
@@ -246,7 +244,8 @@ export function checkBody(
               break;
             }
             case "item": {
-              ty = typeOfItem(fcx.cx, res.id, [], span);
+              // TODO: what do we do about generis here?
+              ty = typeOfItem(fcx.cx, res.id, span);
               break;
             }
             case "builtin":
@@ -592,7 +591,7 @@ function checkStructLiteral(
   }
 
   // TODO: Handle generic arugments
-  const structTy = typeOfItem(fcx.cx, name.res.id, [], name.span);
+  const structTy = typeOfItem(fcx.cx, name.res.id, name.span);
 
   if (structTy.kind !== "struct") {
     const err: ErrorEmitted = emitError(

src/typeck/index.ts

@@ -31,7 +31,7 @@ export function typeck(gcx: GlobalContext, ast: Pkg<Resolved>): Pkg<Typecked> {
       switch (item.kind) {
         case "function": {
           // Functions do not have generic arguments right now.
-          const fnTy = typeOfItem(cx, item.id, [], item.span) as TyFn;
+          const fnTy = typeOfItem(cx, item.id, item.span) as TyFn;
           const body = checkBody(cx, ast, item.body, fnTy);
 
           return {
@@ -43,7 +43,7 @@ export function typeck(gcx: GlobalContext, ast: Pkg<Resolved>): Pkg<Typecked> {
           };
         }
         case "import": {
-          const fnTy = typeOfItem(cx, item.id, [], item.span) as TyFn;
+          const fnTy = typeOfItem(cx, item.id, item.span) as TyFn;
 
           fnTy.params.forEach((param, i) => {
             switch (param.kind) {
@@ -87,7 +87,7 @@ export function typeck(gcx: GlobalContext, ast: Pkg<Resolved>): Pkg<Typecked> {
           };
         }
         case "type": {
-          const ty = typeOfItem(cx, item.id, [], item.span);
+          const ty = typeOfItem(cx, item.id, item.span);
 
           switch (item.type.kind) {
             case "struct": {
@@ -135,7 +135,7 @@ export function typeck(gcx: GlobalContext, ast: Pkg<Resolved>): Pkg<Typecked> {
           return item;
         }
         case "global": {
-          const ty = typeOfItem(cx, item.id, [], item.span);
+          const ty = typeOfItem(cx, item.id, item.span);
           const { init } = item;
 
           let initChecked: Expr<Typecked>;

src/typeck/item.ts

@@ -1,7 +1,7 @@
-import { ItemId, Resolved, Type } from "../ast";
+import { Ident, Item, ItemId, Resolved, Type, Typecked } from "../ast";
 import { CompilerError, Span } from "../error";
 import { printTy } from "../printer";
-import { TYS, Ty, substituteTy } from "../types";
+import { TYS, Ty, createIdentityGenericArgs, substituteTy } from "../types";
 import { TypeckCtx, tyError, tyErrorFrom } from "./base";
 
 function builtinAsTy(cx: TypeckCtx, name: string, span: Span): Ty {
@@ -36,58 +36,77 @@ export function lowerAstTy(cx: TypeckCtx, type: Type<Resolved>): Ty {
       const ident = type.value;
       const res = ident.res;
 
-      const generics = type.generics.map((type) => lowerAstTy(cx, type));
+      const genericArgs = type.genericArgs.map((type) => lowerAstTy(cx, type));
       let ty: Ty;
+      let generics: Generics;
+      // We only actually substitute anything when "peeking" behind a type into its
+      // internals, where the params are used. This is only the case for aliases today.
+      let isAlias = false;
       switch (res.kind) {
         case "local": {
           throw new Error("Item type cannot refer to local variable");
         }
         case "item": {
-          ty = typeOfItem(cx, res.id, generics, type.span);
+          ty = typeOfItem(cx, res.id, type.span);
+          const item = cx.gcx.findItem<Resolved>(res.id, cx.ast);
+          if (item.kind === "type" && item.type.kind === "alias") {
+            isAlias = true;
+          }
+          generics = itemGenerics(item);
           break;
         }
         case "builtin": {
           ty = builtinAsTy(cx, res.name, ident.span);
+          generics = { kind: "none" };
           break;
         }
         case "tyParam": {
           ty = { kind: "param", idx: res.index, name: res.name };
+          generics = { kind: "none" };
           break;
         }
         case "error": {
-          ty = tyErrorFrom(res);
-          break;
+          // Skip generics validation, it's fine!
+          return tyErrorFrom(res);
         }
       }
 
-      if (ty.kind === "struct" || ty.kind === "alias") {
-        if (generics.length === ty.params.length) {
-          if (ty.kind === "alias") {
-            return substituteTy(ty.genericArgs, ty.actual);
-          }
-          return { ...ty, genericArgs: generics };
-        } else {
-          return tyError(
-            cx,
-            new CompilerError(
-              `expected ${ty.params.length} generic arguments, found ${generics.length}`,
-              type.span,
-            ),
-          );
-        }
-      } else if (ty.kind !== "error") {
-        if (generics.length > 0) {
-          return tyError(
-            cx,
-            new CompilerError(
-              `type ${printTy(ty)} does not take generic arguments`,
-              type.span,
-            ),
-          );
-        }
+      if (
+        (generics.kind === "none" || generics.params.length === 0) &&
+        genericArgs.length > 0
+      ) {
+        return tyError(
+          cx,
+          new CompilerError(
+            `type ${printTy(ty)} does not take any generic arguments but ${
+              genericArgs.length
+            } were passed`,
+            type.span,
+          ),
+        );
+      }
+      if (
+        generics.kind === "some" &&
+        generics.params.length > genericArgs.length
+      ) {
+        return tyError(
+          cx,
+          new CompilerError(
+            `missing generics for type ${printTy(ty)}, expected ${
+              generics.params.length
+            }, but only ${genericArgs.length} were passed`,
+            type.span,
+          ),
+        );
+      }
+      if (isAlias) {
+        return substituteTy(genericArgs, ty);
+      } else {
+        if (ty.kind === "struct") {
+          return { ...ty, genericArgs };
+        }
+        return ty;
       }
-
-      return ty;
     }
     case "tuple": {
       return {
@@ -115,12 +134,31 @@ export function lowerAstTy(cx: TypeckCtx, type: Type<Resolved>): Ty {
   }
 }
 
-export function typeOfItem(
-  cx: TypeckCtx,
-  itemId: ItemId,
-  genericArgs: Ty[],
-  cause: Span,
-): Ty {
+type Generics =
+  | {
+      kind: "none";
+    }
+  | {
+      kind: "some";
+      params: Ident[];
+    };
+
+function itemGenerics(item: Item<Typecked> | Item<Resolved>): Generics {
+  const none: Generics = { kind: "none" };
+  switch (item.kind) {
+    case "function":
+    case "extern":
+    case "error":
+    case "global":
+    case "mod":
+    case "import":
+      return none;
+    case "type":
+      return { kind: "some", params: item.genericParams };
+  }
+}
+
+export function typeOfItem(cx: TypeckCtx, itemId: ItemId, cause: Span): Ty {
   if (itemId.pkgId !== cx.ast.id) {
     // Look up foreign items in the foreign pkgs, we don't need to lower those
     // ourselves.
@@ -131,7 +169,7 @@ export function typeOfItem(
       case "import":
       case "type":
       case "global":
-        return substituteTy(genericArgs, item.ty!);
+        return item.ty!;
       case "mod": {
         return tyError(
           cx,
@@ -187,14 +225,7 @@ export function typeOfItem(
         case "struct": {
           ty = {
             kind: "struct",
-            genericArgs: item.generics.map(
-              ({ name }, idx): Ty => ({
-                kind: "param",
-                name,
-                idx,
-              }),
-            ),
-            params: item.generics.map((ident) => ident.name),
+            genericArgs: createIdentityGenericArgs(item.genericParams),
             itemId: item.id,
             _name: item.name,
             fields_no_subst: [
@@ -214,52 +245,41 @@ export function typeOfItem(
         case "alias": {
           const actual = lowerAstTy(cx, item.type.type);
 
-          ty = {
-            kind: "alias",
-            actual,
-            genericArgs: item.generics.map(
-              ({ name }, idx): Ty => ({
-                kind: "param",
-                name,
-                idx,
-              }),
-            ),
-            params: item.generics.map((ident) => ident.name),
-          };
+          ty = actual;
           break;
         }
       }
       break;
     }
     case "mod": {
-      return tyError(
+      ty = tyError(
         cx,
         new CompilerError(
           `module ${item.name} cannot be used as a type or value`,
           cause,
         ),
       );
+      break;
     }
     case "extern": {
-      return tyError(
+      ty = tyError(
         cx,
         new CompilerError(
           `extern declaration ${item.name} cannot be used as a type or value`,
           cause,
         ),
       );
+      break;
     }
     case "global": {
       ty = lowerAstTy(cx, item.type);
       break;
     }
     case "error": {
-      return tyErrorFrom(item);
+      ty = tyErrorFrom(item);
     }
   }
 
-  ty = substituteTy(genericArgs, ty);
-
   cx.itemTys.set(item.id, ty);
   return ty;
 }

src/types.ts

@@ -1,4 +1,4 @@
-import { ItemId, Resolution } from "./ast";
+import { Ident, ItemId, Resolution } from "./ast";
 import { ErrorEmitted } from "./error";
 
 export type TyString = {
@@ -41,7 +41,6 @@ export type TyVar = {
 export type TyStruct = {
   kind: "struct";
   itemId: ItemId;
-  params: string[];
   genericArgs: Ty[];
   _name: string;
   fields_no_subst: [string, Ty][];
@@ -67,13 +66,6 @@ export type TyParam = {
   name: string;
 };
 
-export type TyAlias = {
-  kind: "alias";
-  actual: Ty;
-  genericArgs: Ty[];
-  params: string[];
-};
-
 export type TyError = {
   kind: "error";
   err: ErrorEmitted;
@@ -91,7 +83,6 @@ export type Ty =
   | TyRawPtr
   | TyNever
   | TyParam
-  | TyAlias
   | TyError;
 
 export function tyIsUnit(ty: Ty): ty is TyUnit {
@@ -140,7 +131,6 @@ export function substituteTy(genericArgs: Ty[], ty: Ty): Ty {
         params: ty.params.map(subst),
       };
     case "struct":
-    case "alias":
       return {
         ...ty,
         genericArgs: ty.genericArgs.map(subst),
@@ -158,3 +148,13 @@ export function substituteTy(genericArgs: Ty[], ty: Ty): Ty {
       return ty;
   }
 }
+
+export function createIdentityGenericArgs(params: Ident[]): Ty[] {
+  return params.map(
+    (name, idx): Ty => ({
+      kind: "param",
+      name: name.name,
+      idx,
+    }),
+  );
+}

test.nil

@@ -1,8 +1,8 @@
+type A[T] = struct { a: T };
+type B[T] = struct {
+  b: T,
+};
+
 function main() = ;
 
-type A[T] = T;
-type B[T] = struct { a: T };
-
-//function ohno(x: A[A[A[I32]]]): I32 = x;
-
-function generic(a: B[I32]): B[I32] = a;
+function test(b: B[I32]) = ;

ui-tests/type/generics/aliases_nested.nil

@@ -0,0 +1,6 @@
+//@check-pass
+type A[T] = T;
+
+function ohno(x: A[A[A[I32]]]): I32 = x;
+
+function main() = ;

ui-tests/type/generics/generics_on_primitive.stderr

@@ -1,4 +1,4 @@
-error: type I32 does not take generic arguments
+error: type I32 does not take any generic arguments but 1 were passed
  --> $DIR/generics_on_primitive.nil:2
 2 |     let a: I32[I32] = 0;
                ^^^

ui-tests/type/generics/generics_structs_in_args.stderr

@@ -1,17 +0,0 @@
-/home/nils/projects/riverdelta/target/ast.js:110
-                throw new Error(`substitution out of range, param index ${ty.idx} of param ${ty.name} out of range for length ${genericArgs.length}`);
-                ^
-
-Error: substitution out of range, param index 0 of param T out of range for length 0
-    at substituteTy (/home/nils/projects/riverdelta/target/ast.js:110:23)
-    at subst (/home/nils/projects/riverdelta/target/ast.js:106:27)
-    at Array.map (<anonymous>)
-    at substituteTy (/home/nils/projects/riverdelta/target/ast.js:125:45)
-    at typeOfItem (/home/nils/projects/riverdelta/target/typeck/item.js:193:33)
-    at Object.itemInner (/home/nils/projects/riverdelta/target/typeck/index.js:63:54)
-    at Object.item (/home/nils/projects/riverdelta/target/ast.js:146:34)
-    at /home/nils/projects/riverdelta/target/ast.js:164:55
-    at Array.map (<anonymous>)
-    at foldAst (/home/nils/projects/riverdelta/target/ast.js:164:34)
-
-Node.js v20.10.0

ui-tests/type/generics/structs.nil

@@ -1,3 +1,4 @@
+//@check-pass
 type A[T] = struct { a: T };
 type B[T, U, V] = struct {
   b: T,
@@ -6,3 +7,5 @@ type B[T, U, V] = struct {
 type C = ();
 
 function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;
+
+function main() = ;

ui-tests/type/generics/structs.stderr

@@ -1,17 +0,0 @@
-/home/nils/projects/riverdelta/target/ast.js:110
-                throw new Error(`substitution out of range, param index ${ty.idx} of param ${ty.name} out of range for length ${genericArgs.length}`);
-                ^
-
-Error: substitution out of range, param index 0 of param T out of range for length 0
-    at substituteTy (/home/nils/projects/riverdelta/target/ast.js:110:23)
-    at subst (/home/nils/projects/riverdelta/target/ast.js:106:27)
-    at Array.map (<anonymous>)
-    at substituteTy (/home/nils/projects/riverdelta/target/ast.js:125:45)
-    at typeOfItem (/home/nils/projects/riverdelta/target/typeck/item.js:193:33)
-    at Object.itemInner (/home/nils/projects/riverdelta/target/typeck/index.js:63:54)
-    at Object.item (/home/nils/projects/riverdelta/target/ast.js:146:34)
-    at /home/nils/projects/riverdelta/target/ast.js:164:55
-    at Array.map (<anonymous>)
-    at foldAst (/home/nils/projects/riverdelta/target/ast.js:164:34)
-
-Node.js v20.10.0

ui-tests/type/generics/wrong_amount.nil

@@ -21,3 +21,5 @@ function test(
     c2: C[],
     c3: C[I32],
 ) = ;
+
+function main() = ;

ui-tests/type/generics/wrong_amount.stderr

@@ -1,17 +1,24 @@
-/home/nils/projects/riverdelta/target/ast.js:110
-                throw new Error(`substitution out of range, param index ${ty.idx} of param ${ty.name} out of range for length ${genericArgs.length}`);
-                ^
-
-Error: substitution out of range, param index 0 of param T out of range for length 0
-    at substituteTy (/home/nils/projects/riverdelta/target/ast.js:110:23)
-    at subst (/home/nils/projects/riverdelta/target/ast.js:106:27)
-    at Array.map (<anonymous>)
-    at substituteTy (/home/nils/projects/riverdelta/target/ast.js:125:45)
-    at typeOfItem (/home/nils/projects/riverdelta/target/typeck/item.js:193:33)
-    at Object.itemInner (/home/nils/projects/riverdelta/target/typeck/index.js:63:54)
-    at Object.item (/home/nils/projects/riverdelta/target/ast.js:146:34)
-    at /home/nils/projects/riverdelta/target/ast.js:164:55
-    at Array.map (<anonymous>)
-    at foldAst (/home/nils/projects/riverdelta/target/ast.js:164:34)
-
-Node.js v20.10.0
+error: missing generics for type A, expected 1, but only 0 were passed
+ --> $DIR/wrong_amount.nil:9
+9 |     a1: A,
+            ^
+error: missing generics for type A, expected 1, but only 0 were passed
+ --> $DIR/wrong_amount.nil:10
+10 |     a2: A[],
+             ^
+error: missing generics for type B, expected 3, but only 0 were passed
+ --> $DIR/wrong_amount.nil:14
+14 |     b1: B,
+             ^
+error: missing generics for type B, expected 3, but only 0 were passed
+ --> $DIR/wrong_amount.nil:15
+15 |     b2: B[],
+             ^
+error: missing generics for type B, expected 3, but only 2 were passed
+ --> $DIR/wrong_amount.nil:16
+16 |     b3: B[Int, Int],
+             ^
+error: type () does not take any generic arguments but 1 were passed
+ --> $DIR/wrong_amount.nil:22
+22 |     c3: C[I32],
+             ^