Detect unused variables

src/ast.ts

@@ -134,9 +134,8 @@ export type ItemKindFunction<P extends Phase> = {
 };
 
 export type FunctionArg<P extends Phase> = {
-  name: string;
+  ident: Ident;
   type: Type<P>;
-  span: Span;
 };
 
 export type ItemKindType<P extends Phase> = {
@@ -449,6 +448,8 @@ export type Resolution =
        * ```
        * When traversing resolutions, a stack of locals has to be kept.
        * It's similar to a De Bruijn index.
+       * 
+       * You generally want to index the stack as stack[stack.len - 1 - res.idx].
        */
       index: number;
     }
@@ -577,10 +578,9 @@ export function superFoldItem<From extends Phase, To extends Phase>(
 ): Item<To> {
   switch (item.kind) {
     case "function": {
-      const args = item.params.map(({ name, type, span }) => ({
-        name,
+      const args = item.params.map(({ ident, type }) => ({
+        ident,
         type: folder.type(type),
-        span,
       }));
 
       return {
@@ -620,10 +620,9 @@ export function superFoldItem<From extends Phase, To extends Phase>(
       };
     }
     case "import": {
-      const args = item.params.map(({ name, type, span }) => ({
-        name,
+      const args = item.params.map(({ ident, type }) => ({
+        ident,
         type: folder.type(type),
-        span,
       }));
       return {
         ...item,

src/context.ts

@@ -81,6 +81,7 @@ export type Options = {
   packageName: string;
   debug: Set<string>;
   noOutput: boolean;
+  noStd: boolean;
 };
 
 export function parseArgs(hardcodedInput: string): Options {
@@ -89,6 +90,7 @@ export function parseArgs(hardcodedInput: string): Options {
   let packageName: string;
   let debug = new Set<string>();
   let noOutput = false;
+  let noStd = false;
 
   if (process.argv.length > 2) {
     filename = process.argv[2];
@@ -117,6 +119,9 @@ export function parseArgs(hardcodedInput: string): Options {
     if (process.argv.some((arg) => arg === "--no-output")) {
       noOutput = true;
     }
+    if (process.argv.some((arg) => arg === "--no-std")) {
+      noStd = true;
+    }
   } else {
     filename = "<hardcoded>";
     input = hardcodedInput;
@@ -136,5 +141,6 @@ export function parseArgs(hardcodedInput: string): Options {
     packageName,
     debug,
     noOutput,
+    noStd,
   };
 }

src/error.ts

@@ -44,12 +44,18 @@ export class ErrorHandler {
     private emitter = (msg: string) => globalThis.console.error(msg),
   ) {}
 
-  public emit(err: CompilerError): ErrorEmitted {
-    renderError(this.emitter, err);
+  public emitError(err: CompilerError): ErrorEmitted {
+    renderDiagnostic(this.emitter, err, (msg) => chalk.red(`error: ${msg}`));
     this.errors.push(err);
     return ERROR_EMITTED;
   }
 
+  public warn(err: CompilerError): void {
+    renderDiagnostic(this.emitter, err, (msg) =>
+      chalk.yellow(`warning: ${msg}`),
+    );
+  }
+
   public hasErrors(): boolean {
     return this.errors.length > 0;
   }
@@ -72,7 +78,11 @@ export class CompilerError {
 // eslint-disable-next-line @typescript-eslint/no-unused-vars
 const console = {};
 
-function renderError(emitter: Emitter, e: CompilerError) {
+function renderDiagnostic(
+  emitter: Emitter,
+  e: CompilerError,
+  render_msg: (msg: string) => string,
+) {
   const { span } = e;
   const { content } = span.file;
 
@@ -88,7 +98,7 @@ function renderError(emitter: Emitter, e: CompilerError) {
   }
   const lineIdx = lineSpans.indexOf(line);
   const lineNo = lineIdx + 1;
-  emitter(chalk.red(`error: ${e.msg}`));
+  emitter(render_msg(e.msg));
   emitter(` --> ${span.file.path ?? "<unknown>"}:${lineNo}`);
 
   emitter(`${lineNo} | ${spanToSnippet(content, line)}`);

src/index.ts

@@ -44,7 +44,7 @@ function main() {
 
   const start = Date.now();
 
-  if (packageName !== "std") {
+  if (packageName !== "std" && !opts.noStd) {
     gcx.pkgLoader(gcx, "std", Span.startOfFile(file));
   }
 

src/lexer.ts

@@ -114,7 +114,7 @@ export function tokenize(handler: ErrorHandler, file: LoadedFile): LexerResult {
     return { ok: true, tokens: tokenizeInner(file) };
   } catch (e) {
     if (e instanceof LexerError) {
-      const err: ErrorEmitted = handler.emit(e.inner);
+      const err: ErrorEmitted = handler.emitError(e.inner);
       return { ok: false, err };
     } else {
       throw e;

src/loader.ts

@@ -104,7 +104,7 @@ export const loadPkg: PkgLoader = (
     return dummyErrorPkg(
       pkgId,
       name,
-      gcx.error.emit(
+      gcx.error.emitError(
         new CompilerError(`cycle detected loading extern module ${name}`, span),
       ),
     );
@@ -118,7 +118,7 @@ export const loadPkg: PkgLoader = (
 
   const file = loadModuleFile(".", name, span);
   if (!file.ok) {
-    return dummyErrorPkg(pkgId, name, gcx.error.emit(file.err));
+    return dummyErrorPkg(pkgId, name, gcx.error.emitError(file.err));
   }
 
   const tokens = tokenize(gcx.error, file.value);

src/parser.ts

@@ -233,7 +233,7 @@ function parseItem(t: State): [State, Item<Parsed>] {
       [t] = expectNext(t, ")");
     } else {
       if (name.span.file.path === undefined) {
-        t.gcx.error.emit(
+        t.gcx.error.emitError(
           new CompilerError(
             `no known source file for statement, cannot load file relative to it`,
             name.span,
@@ -245,7 +245,7 @@ function parseItem(t: State): [State, Item<Parsed>] {
         const file = loadModuleFile(name.span.file.path, name.ident, name.span);
 
         if (!file.ok) {
-          t.gcx.error.emit(file.err);
+          t.gcx.error.emitError(file.err);
           contents = [];
         } else {
           const tokens = tokenize(t.gcx.error, file.value);
@@ -311,15 +311,19 @@ function parseFunctionSig(t: State): [State, FunctionSig] {
   [t] = expectNext(t, "(");
 
   let params: FunctionArg<Parsed>[];
-  [t, params] = parseCommaSeparatedList(t, ")", (t) => {
-    let name;
-    [t, name] = expectNext<TokenIdent>(t, "identifier");
-    [t] = expectNext(t, ":");
-    let type;
-    [t, type] = parseType(t);
+  [t, params] = parseCommaSeparatedList(
+    t,
+    ")",
+    (t): [State, FunctionArg<Parsed>] => {
+      let name;
+      [t, name] = expectNext<TokenIdent>(t, "identifier");
+      [t] = expectNext(t, ":");
+      let type;
+      [t, type] = parseType(t);
 
-    return [t, { name: name.ident, type, span: name.span }];
-  });
+      return [t, { ident: { name: name.ident, span: name.span }, type }];
+    },
+  );
 
   let colon;
   let returnType = undefined;
@@ -732,7 +736,7 @@ function parseType(t: State): [State, Type<Parsed>] {
     }
     default: {
       throw new FatalParseError(
-        t.gcx.error.emit(
+        t.gcx.error.emitError(
           new CompilerError(
             `unexpected token: \`${tok.kind}\`, expected type`,
             span,
@@ -799,7 +803,7 @@ function expectNext<T extends BaseToken>(
   [t, tok] = maybeNextT(t);
   if (!tok) {
     throw new FatalParseError(
-      t.gcx.error.emit(
+      t.gcx.error.emitError(
         new CompilerError(
           `expected \`${kind}\`, found end of file`,
           Span.eof(t.file),
@@ -809,7 +813,7 @@ function expectNext<T extends BaseToken>(
   }
   if (tok.kind !== kind) {
     throw new FatalParseError(
-      t.gcx.error.emit(
+      t.gcx.error.emitError(
         new CompilerError(
           `expected \`${kind}\`, found \`${tok.kind}\``,
           tok.span,
@@ -824,7 +828,7 @@ function next(t: State): [State, Token] {
   const [rest, next] = maybeNextT(t);
   if (!next) {
     throw new FatalParseError(
-      t.gcx.error.emit(
+      t.gcx.error.emitError(
         new CompilerError("unexpected end of file", Span.eof(t.file)),
       ),
     );
@@ -841,7 +845,7 @@ function maybeNextT(t: State): [State, Token | undefined] {
 
 function unexpectedToken(t: ParseState, token: Token, expected: string): never {
   throw new FatalParseError(
-    t.gcx.error.emit(
+    t.gcx.error.emitError(
       new CompilerError(`unexpected token, expected ${expected}`, token.span),
     ),
   );
@@ -875,7 +879,7 @@ function validateAst(ast: Pkg<Built>, gcx: GlobalContext) {
         });
         return expr;
       } else if (expr.kind === "let") {
-        gcx.error.emit(
+        gcx.error.emitError(
           new CompilerError("let is only allowed in blocks", expr.span),
         );
         return superFoldExpr(expr, this);
@@ -886,7 +890,7 @@ function validateAst(ast: Pkg<Built>, gcx: GlobalContext) {
             const innerClass = binaryExprPrecedenceClass(inner.binaryKind);
 
             if (ourClass !== innerClass) {
-              gcx.error.emit(
+              gcx.error.emitError(
                 new CompilerError(
                   `mixing operators without parentheses is not allowed. ${side} is ${inner.binaryKind}, which is different from ${expr.binaryKind}`,
                   expr.span,

src/printer.ts

@@ -57,7 +57,7 @@ function printItem(item: Item<AnyPhase>): string {
 
 function printFunction(func: ItemFunction<AnyPhase>): string {
   const args = func.params
-    .map(({ name, type }) => `${name}: ${printType(type)}`)
+    .map(({ ident: name, type }) => `${name}: ${printType(type)}`)
     .join(", ");
   const ret = func.returnType ? `: ${printType(func.returnType)}` : "";
   return `function ${func.name}(${args})${ret} = ${printExpr(func.body, 0)};`;
@@ -89,7 +89,7 @@ function printTypeDef(type: ItemType<AnyPhase>): string {
 
 function printImportDef(def: ItemImport<AnyPhase>): string {
   const args = def.params
-    .map(({ name, type }) => `${name}: ${printType(type)}`)
+    .map(({ ident: name, type }) => `${name}: ${printType(type)}`)
     .join(", ");
   const ret = def.returnType ? `: ${printType(def.returnType)}` : "";
 

src/resolve.ts

@@ -92,7 +92,7 @@ function resolveModule(
   contents.forEach((item) => {
     const existing = items.get(item.name);
     if (existing !== undefined) {
-      cx.gcx.error.emit(
+      cx.gcx.error.emitError(
         new CompilerError(
           `item \`${item.name}\` has already been declared`,
           item.span,
@@ -164,7 +164,7 @@ function resolveModule(
 
     return {
       kind: "error",
-      err: cx.gcx.error.emit(
+      err: cx.gcx.error.emitError(
         new CompilerError(`cannot find ${ident.name}`, ident.span),
       ),
     };
@@ -179,18 +179,17 @@ function resolveModule(
 
       switch (item.kind) {
         case "function": {
-          const params = item.params.map(({ name, span, type }) => ({
-            name,
-            span,
+          const params = item.params.map(({ ident, type }) => ({
+            ident,
             type: this.type(type),
           }));
           const returnType = item.returnType && this.type(item.returnType);
 
-          item.params.forEach(({ name }) => scopes.push(name));
+          item.params.forEach(({ ident: name }) => scopes.push(name.name));
           const body = this.expr(item.body);
           const revParams = item.params.slice();
           revParams.reverse();
-          revParams.forEach(({ name }) => popScope(name));
+          revParams.forEach(({ ident: name }) => popScope(name.name));
 
           return {
             kind: "function",
@@ -289,7 +288,7 @@ function resolveModule(
                 let pathRes: Resolution;
 
                 if (typeof expr.field.value === "number") {
-                  const err: ErrorEmitted = cx.gcx.error.emit(
+                  const err: ErrorEmitted = cx.gcx.error.emitError(
                     new CompilerError(
                       "module contents cannot be indexed with a number",
                       expr.field.span,
@@ -304,7 +303,7 @@ function resolveModule(
                   );
 
                   if (pathResItem === undefined) {
-                    const err: ErrorEmitted = cx.gcx.error.emit(
+                    const err: ErrorEmitted = cx.gcx.error.emitError(
                       new CompilerError(
                         `module ${module.name} has no item ${expr.field.value}`,
                         expr.field.span,

src/typeck/base.ts

@@ -32,5 +32,5 @@ export function tyErrorFrom(prev: { err: ErrorEmitted }): Ty {
 }
 
 export function emitError(cx: TypeckCtx, err: CompilerError): ErrorEmitted {
-  return cx.gcx.error.emit(err);
+  return cx.gcx.error.emitError(err);
 }

src/typeck/index.ts

@@ -17,6 +17,7 @@ import { emitError } from "./base";
 import { checkBody, exprError } from "./expr";
 import { InferContext } from "./infer";
 import { typeOfItem } from "./item";
+import { lintProgram } from "./lint";
 
 export function typeck(gcx: GlobalContext, ast: Pkg<Resolved>): Pkg<Typecked> {
   const cx = {
@@ -55,7 +56,7 @@ export function typeck(gcx: GlobalContext, ast: Pkg<Resolved>): Pkg<Typecked> {
                   cx,
                   new CompilerError(
                     `import parameters must be I32 or Int`,
-                    item.params[i].span,
+                    item.params[i].ident.span,
                   ),
                 );
               }
@@ -214,5 +215,7 @@ export function typeck(gcx: GlobalContext, ast: Pkg<Resolved>): Pkg<Typecked> {
     }
   }
 
+  lintProgram(gcx, typecked);
+
   return typecked;
 }

src/typeck/infer.ts

@@ -162,7 +162,7 @@ export class InferContext {
       }
     }
 
-    this.error.emit(
+    this.error.emitError(
       new CompilerError(
         `cannot assign ${printTy(rhs)} to ${printTy(lhs)}`,
         span,

src/typeck/lint.ts

@@ -0,0 +1,108 @@
+import {
+  Folder,
+  Ident,
+  Item,
+  Pkg,
+  Typecked,
+  foldAst,
+  mkDefaultFolder,
+  superFoldExpr,
+  superFoldItem,
+} from "../ast";
+import { GlobalContext } from "../context";
+import { CompilerError } from "../error";
+
+type LintContext = {
+  locals: LocalUsed[];
+};
+
+type LocalUsed = {
+  ident: Ident;
+  used: boolean;
+  isParam: boolean;
+};
+
+export function lintProgram(gcx: GlobalContext, ast: Pkg<Typecked>): void {
+  const cx: LintContext = {
+    locals: [],
+  };
+
+  const checker: Folder<Typecked, Typecked> = {
+    ...mkDefaultFolder(),
+    itemInner(item: Item<Typecked>): Item<Typecked> {
+      switch (item.kind) {
+        case "function": {
+          const prev = cx.locals;
+          cx.locals = [
+            ...item.params.map((param) => ({
+              ident: param.ident,
+              used: false,
+              isParam: true,
+            })),
+          ];
+          superFoldItem(item, this);
+          checkLocalsUsed(gcx, 0, cx);
+          cx.locals = prev;
+          return item;
+        }
+      }
+      return superFoldItem(item, this);
+    },
+    expr(expr) {
+      switch (expr.kind) {
+        case "let": {
+          superFoldExpr(expr, this);
+          cx.locals.push({ ident: expr.name, used: false, isParam: false });
+          return expr;
+        }
+        case "block": {
+          const prevLocalsLen = cx.locals.length;
+          superFoldExpr(expr, this);
+          checkLocalsUsed(gcx, prevLocalsLen, cx);
+          cx.locals.length = prevLocalsLen;
+
+          return expr;
+        }
+        case "ident": {
+          const { res } = expr.value;
+          switch (res.kind) {
+            case "local": {
+              cx.locals[cx.locals.length - 1 - res.index].used = true;
+              break;
+            }
+          }
+          return superFoldExpr(expr, this);
+        }
+      }
+
+      return superFoldExpr(expr, this);
+    },
+    ident(ident) {
+      return ident;
+    },
+    type(type) {
+      return type;
+    },
+  };
+
+  foldAst(ast, checker);
+}
+
+function checkLocalsUsed(
+  gcx: GlobalContext,
+  prevLength: number,
+  cx: LintContext,
+) {
+  for (let i = prevLength; i < cx.locals.length; i++) {
+    const local = cx.locals[i];
+    if (!local.used && !local.ident.name.startsWith("_")) {
+      const kind = local.isParam ? "function parameter" : "variable";
+      gcx.error.warn(
+        new CompilerError(
+          `unused ${kind}: \`${local.ident.name}\``,
+          local.ident.span,
+        ),
+      );
+    }
+  }
+}

std/io.nil

@@ -2,5 +2,6 @@ import ("wasi_snapshot_preview1" "fd_write")
     fd_write(fd: I32, ciovec_ptr: I32, ciovec_len: I32, out_ptr: I32): I32;
 
 function print(s: String) = (
-    let s: (I32, I32) = ___transmute(s);
+    // TODO: do it
+    let _s: (I32, I32) = ___transmute(s);
 );

std/rt/alloc.nil

@@ -29,7 +29,7 @@ function allocate(size: I32, align: I32): I32 = (
     alignedPtr
 );
 
-function deallocate(ptr: I32, size: I32) = (
+function deallocate(_ptr: I32, _size: I32) = (
     std.println("uwu deawwocate :3");
 );
 

std/rt/rt.mod.nil

@@ -1,6 +1,7 @@
 mod alloc;
 
-function memcpy(dst: I32, src: I32, n: I32) = 
+// The function parameters are not actually unused.
+function memcpy(_dst: I32, _src: I32, _n: I32) = 
     ___asm(
         __locals(),
         "local.get 2",

ui-tests/asm/drop.nil

@@ -1,6 +1,6 @@
 //@check-pass
 
-function dropping(a: I32) =
+function dropping(_a: I32) =
     ___asm(
         __locals(),
         "local.get 0",

ui-tests/asm/instr_not_string.nil

@@ -1,4 +1,4 @@
-function a(a: I32) =
+function a(_a: I32) =
     ___asm(
         __locals(),
         0,

ui-tests/asm/invalid_instr.nil

@@ -1,4 +1,4 @@
-function dropping(a: I32) =
+function dropping(_a: I32) =
     ___asm(
         __locals(),
         "meow meow",

ui-tests/asm/missing_locals.nil

@@ -1,4 +1,4 @@
-function dropping(a: I32) =
+function dropping(_a: I32) =
     ___asm(
         "local.get 0",
         "drop",

ui-tests/asm/not_toplevel.nil

@@ -1,4 +1,4 @@
-function dropping(a: I32) = (
+function dropping(_a: I32) = (
     1;
     ___asm(__locals(), "drop");
 );

ui-tests/asm/wrong_imm.nil

@@ -1,11 +1,11 @@
-function a(a: I32) =
+function a(_a: I32) =
     ___asm(
         __locals(),
         "local.get 0 0",
         "drop",
     );
 
-function b(a: I32) =
+function b(_a: I32) =
     ___asm(
         __locals(),
         "local.get",

ui-tests/basic_recovery.stderr

@@ -10,3 +10,11 @@ error: cannot assign String to Int
  --> $DIR/basic_recovery.nil:3
 3 |   let b: Int = "";
           ^
+warning: unused variable: `a`
+ --> $DIR/basic_recovery.nil:2
+2 |   let a: Int = "";
+          ^
+warning: unused variable: `b`
+ --> $DIR/basic_recovery.nil:3
+3 |   let b: Int = "";
+          ^

ui-tests/functions/function_calls_ok.nil

@@ -5,14 +5,14 @@ function main() = (
     singleArg("hi!");
     manyArgs(1,2,3,4,5,6);
 
-    let a: () = returnNothing();
-    let b: () = returnExplicitUnit();
-    let c: String = returnString();
+    let _a: () = returnNothing();
+    let _b: () = returnExplicitUnit();
+    let _c: String = returnString();
 );
 
 function noArgs() =;
-function singleArg(a: String) =;
-function manyArgs(a: Int, b: Int, c: Int, d: Int, e: Int, f: Int) =;
+function singleArg(_a: String) =;
+function manyArgs(_a: Int, _b: Int, _c: Int, _d: Int, _e: Int, _f: Int) =;
 
 function returnNothing() =;
 function returnExplicitUnit(): () =;

ui-tests/functions/missing_args.nil

@@ -2,4 +2,4 @@ function main() = (
     x();
 );
 
-function x(a: Int) = ;
+function x(_a: Int) = ;

ui-tests/lint/unused_vars.nil

@@ -0,0 +1,22 @@
+//@check-pass
+
+function main() = (
+  let x = 0;
+  let _ok = 0;
+  let used = 0;
+
+  used;
+);
+
+function x() = (
+  let x = 0;
+  (
+    let x = 0;
+    call(x);
+  );
+  let y = x;
+);
+
+function call(_a: Int) = ;
+
+function param(p: Int) = ;

ui-tests/lint/unused_vars.stderr

@@ -0,0 +1,12 @@
+warning: unused variable: `x`
+ --> $DIR/unused_vars.nil:4
+4 |   let x = 0;
+          ^
+warning: unused variable: `y`
+ --> $DIR/unused_vars.nil:17
+17 |   let y = x;
+           ^
+warning: unused function parameter: `p`
+ --> $DIR/unused_vars.nil:22
+22 | function param(p: Int) = ;
+                    ^

ui-tests/type/generics/generics_on_primitive.stderr

@@ -2,3 +2,7 @@ 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;
                ^^^
+warning: unused variable: `a`
+ --> $DIR/generics_on_primitive.nil:2
+2 |     let a: I32[I32] = 0;
+            ^

ui-tests/type/generics/generics_structs_in_args.stderr

@@ -0,0 +1,12 @@
+warning: unused function parameter: `a`
+ --> $DIR/generics_structs_in_args.nil:11
+11 | function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;
+                   ^
+warning: unused function parameter: `b`
+ --> $DIR/generics_structs_in_args.nil:11
+11 | function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;
+                              ^
+warning: unused function parameter: `c`
+ --> $DIR/generics_structs_in_args.nil:11
+11 | function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;
+                                                   ^

ui-tests/type/generics/structs.stderr

@@ -0,0 +1,12 @@
+warning: unused function parameter: `a`
+ --> $DIR/structs.nil:9
+9 | function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;
+                  ^
+warning: unused function parameter: `b`
+ --> $DIR/structs.nil:9
+9 | function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;
+                             ^
+warning: unused function parameter: `c`
+ --> $DIR/structs.nil:9
+9 | function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;
+                                                  ^

ui-tests/type/generics/wrong_amount.stderr

@@ -22,3 +22,51 @@ error: type () does not take any generic arguments but 1 were passed
  --> $DIR/wrong_amount.nil:22
 22 |     c3: C[I32],
              ^
+warning: unused function parameter: `a1`
+ --> $DIR/wrong_amount.nil:9
+9 |     a1: A,
+        ^^
+warning: unused function parameter: `a2`
+ --> $DIR/wrong_amount.nil:10
+10 |     a2: A[],
+         ^^
+warning: unused function parameter: `a3`
+ --> $DIR/wrong_amount.nil:11
+11 |     a3: A[I32],
+         ^^
+warning: unused function parameter: `a4`
+ --> $DIR/wrong_amount.nil:12
+12 |     a4: A[I32, I32],
+         ^^
+warning: unused function parameter: `b1`
+ --> $DIR/wrong_amount.nil:14
+14 |     b1: B,
+         ^^
+warning: unused function parameter: `b2`
+ --> $DIR/wrong_amount.nil:15
+15 |     b2: B[],
+         ^^
+warning: unused function parameter: `b3`
+ --> $DIR/wrong_amount.nil:16
+16 |     b3: B[Int, Int],
+         ^^
+warning: unused function parameter: `b4`
+ --> $DIR/wrong_amount.nil:17
+17 |     b4: B[Int, I32, Int],
+         ^^
+warning: unused function parameter: `b5`
+ --> $DIR/wrong_amount.nil:18
+18 |     b5: B[Int, Int, Int, Int],
+         ^^
+warning: unused function parameter: `c1`
+ --> $DIR/wrong_amount.nil:20
+20 |     c1: C,
+         ^^
+warning: unused function parameter: `c2`
+ --> $DIR/wrong_amount.nil:21
+21 |     c2: C[],
+         ^^
+warning: unused function parameter: `c3`
+ --> $DIR/wrong_amount.nil:22
+22 |     c3: C[I32],
+         ^^

ui-tests/type/type_alias.stderr

@@ -0,0 +1,4 @@
+warning: unused variable: `a`
+ --> $DIR/type_alias.nil:6
+6 |     let a: A = (0, 0);
+            ^

ui-tests/type/type_assignments.stderr

@@ -0,0 +1,24 @@
+warning: unused variable: `a1`
+ --> $DIR/type_assignments.nil:15
+15 |     let a1: Int = a;
+             ^^
+warning: unused variable: `b1`
+ --> $DIR/type_assignments.nil:16
+16 |     let b1: I32 = b;
+             ^^
+warning: unused variable: `c1`
+ --> $DIR/type_assignments.nil:17
+17 |     let c1: String = c;
+             ^^
+warning: unused variable: `d1`
+ --> $DIR/type_assignments.nil:18
+18 |     let d1: Bool = d;
+             ^^
+warning: unused variable: `e1`
+ --> $DIR/type_assignments.nil:19
+19 |     let e1: CustomType = e;
+             ^^
+warning: unused variable: `f1`
+ --> $DIR/type_assignments.nil:20
+20 |     let f1: (Int, I32) = f;
+             ^^