Auto merge of #17455 - Veykril:vscode-ext, r=Veykril

Tidy up vscode extension a bit

16 files changed, 143 insertions, 171 deletions

diff --git a/src/tools/rust-analyzer/editors/code/src/ast_inspector.ts b/src/tools/rust-analyzer/editors/code/src/ast_inspector.ts
index 688c53a9b1f..35b705c477e 100644
--- a/src/tools/rust-analyzer/editors/code/src/ast_inspector.ts
+++ b/src/tools/rust-analyzer/editors/code/src/ast_inspector.ts
@@ -1,8 +1,7 @@
 import * as vscode from "vscode";
 
 import type { Ctx, Disposable } from "./ctx";
-import { type RustEditor, isRustEditor } from "./util";
-import { unwrapUndefinable } from "./undefinable";
+import { type RustEditor, isRustEditor, unwrapUndefinable } from "./util";
 
 // FIXME: consider implementing this via the Tree View API?
 // https://code.visualstudio.com/api/extension-guides/tree-view
diff --git a/src/tools/rust-analyzer/editors/code/src/bootstrap.ts b/src/tools/rust-analyzer/editors/code/src/bootstrap.ts
index 6cf399599d9..5a92b285ae6 100644
--- a/src/tools/rust-analyzer/editors/code/src/bootstrap.ts
+++ b/src/tools/rust-analyzer/editors/code/src/bootstrap.ts
@@ -1,9 +1,9 @@
 import * as vscode from "vscode";
 import * as os from "os";
 import type { Config } from "./config";
-import { log, isValidExecutable } from "./util";
+import { type Env, log } from "./util";
 import type { PersistentState } from "./persistent_state";
-import { exec } from "child_process";
+import { exec, spawnSync } from "child_process";
 
 export async function bootstrap(
     context: vscode.ExtensionContext,
@@ -13,7 +13,7 @@ export async function bootstrap(
     const path = await getServer(context, config, state);
     if (!path) {
         throw new Error(
-            "Rust Analyzer Language Server is not available. " +
+            "rust-analyzer Language Server is not available. " +
                 "Please, ensure its [proper installation](https://rust-analyzer.github.io/manual.html#installation).",
         );
     }
@@ -21,12 +21,12 @@ export async function bootstrap(
     log.info("Using server binary at", path);
 
     if (!isValidExecutable(path, config.serverExtraEnv)) {
-        if (config.serverPath) {
-            throw new Error(`Failed to execute ${path} --version. \`config.server.path\` or \`config.serverPath\` has been set explicitly.\
-            Consider removing this config or making a valid server binary available at that path.`);
-        } else {
-            throw new Error(`Failed to execute ${path} --version`);
-        }
+        throw new Error(
+            `Failed to execute ${path} --version.` + config.serverPath
+                ? `\`config.server.path\` or \`config.serverPath\` has been set explicitly.\
+            Consider removing this config or making a valid server binary available at that path.`
+                : "",
+        );
     }
 
     return path;
@@ -54,27 +54,12 @@ async function getServer(
     if (bundledExists) {
         let server = bundled;
         if (await isNixOs()) {
-            await vscode.workspace.fs.createDirectory(config.globalStorageUri).then();
-            const dest = vscode.Uri.joinPath(config.globalStorageUri, `rust-analyzer${ext}`);
-            let exists = await vscode.workspace.fs.stat(dest).then(
-                () => true,
-                () => false,
-            );
-            if (exists && config.package.version !== state.serverVersion) {
-                await vscode.workspace.fs.delete(dest);
-                exists = false;
-            }
-            if (!exists) {
-                await vscode.workspace.fs.copy(bundled, dest);
-                await patchelf(dest);
-            }
-            server = dest;
+            server = await getNixOsServer(config, ext, state, bundled, server);
+            await state.updateServerVersion(config.package.version);
         }
-        await state.updateServerVersion(config.package.version);
         return server.fsPath;
     }
 
-    await state.updateServerVersion(undefined);
     await vscode.window.showErrorMessage(
         "Unfortunately we don't ship binaries for your platform yet. " +
             "You need to manually clone the rust-analyzer repository and " +
@@ -86,6 +71,45 @@ async function getServer(
     return undefined;
 }
 
+export function isValidExecutable(path: string, extraEnv: Env): boolean {
+    log.debug("Checking availability of a binary at", path);
+
+    const res = spawnSync(path, ["--version"], {
+        encoding: "utf8",
+        env: { ...process.env, ...extraEnv },
+    });
+
+    const printOutput = res.error ? log.warn : log.info;
+    printOutput(path, "--version:", res);
+
+    return res.status === 0;
+}
+
+async function getNixOsServer(
+    config: Config,
+    ext: string,
+    state: PersistentState,
+    bundled: vscode.Uri,
+    server: vscode.Uri,
+) {
+    await vscode.workspace.fs.createDirectory(config.globalStorageUri).then();
+    const dest = vscode.Uri.joinPath(config.globalStorageUri, `rust-analyzer${ext}`);
+    let exists = await vscode.workspace.fs.stat(dest).then(
+        () => true,
+        () => false,
+    );
+    if (exists && config.package.version !== state.serverVersion) {
+        await vscode.workspace.fs.delete(dest);
+        exists = false;
+    }
+    if (!exists) {
+        await vscode.workspace.fs.copy(bundled, dest);
+        await patchelf(dest);
+    }
+    server = dest;
+    return server;
+}
+
 async function isNixOs(): Promise<boolean> {
     try {
         const contents = (
diff --git a/src/tools/rust-analyzer/editors/code/src/client.ts b/src/tools/rust-analyzer/editors/code/src/client.ts
index f679c883983..1c2a34b484d 100644
--- a/src/tools/rust-analyzer/editors/code/src/client.ts
+++ b/src/tools/rust-analyzer/editors/code/src/client.ts
@@ -3,73 +3,13 @@ import * as lc from "vscode-languageclient/node";
 import * as vscode from "vscode";
 import * as ra from "../src/lsp_ext";
 import * as Is from "vscode-languageclient/lib/common/utils/is";
-import { assert } from "./util";
+import { assert, unwrapUndefinable } from "./util";
 import * as diagnostics from "./diagnostics";
 import { WorkspaceEdit } from "vscode";
 import { type Config, prepareVSCodeConfig } from "./config";
-import { randomUUID } from "crypto";
 import { sep as pathSeparator } from "path";
-import { unwrapUndefinable } from "./undefinable";
 import { RaLanguageClient } from "./lang_client";
 
-export interface Env {
-    [name: string]: string;
-}
-
-// Command URIs have a form of command:command-name?arguments, where
-// arguments is a percent-encoded array of data we want to pass along to
-// the command function. For "Show References" this is a list of all file
-// URIs with locations of every reference, and it can get quite long.
-//
-// To work around it we use an intermediary linkToCommand command. When
-// we render a command link, a reference to a command with all its arguments
-// is stored in a map, and instead a linkToCommand link is rendered
-// with the key to that map.
-export const LINKED_COMMANDS = new Map<string, ra.CommandLink>();
-
-// For now the map is cleaned up periodically (I've set it to every
-// 10 minutes). In general case we'll probably need to introduce TTLs or
-// flags to denote ephemeral links (like these in hover popups) and
-// persistent links and clean those separately. But for now simply keeping
-// the last few links in the map should be good enough. Likewise, we could
-// add code to remove a target command from the map after the link is
-// clicked, but assuming most links in hover sheets won't be clicked anyway
-// this code won't change the overall memory use much.
-setInterval(
-    function cleanupOlderCommandLinks() {
-        // keys are returned in insertion order, we'll keep a few
-        // of recent keys available, and clean the rest
-        const keys = [...LINKED_COMMANDS.keys()];
-        const keysToRemove = keys.slice(0, keys.length - 10);
-        for (const key of keysToRemove) {
-            LINKED_COMMANDS.delete(key);
-        }
-    },
-    10 * 60 * 1000,
-);
-
-function renderCommand(cmd: ra.CommandLink): string {
-    const commandId = randomUUID();
-    LINKED_COMMANDS.set(commandId, cmd);
-    return `[${cmd.title}](command:rust-analyzer.linkToCommand?${encodeURIComponent(
-        JSON.stringify([commandId]),
-    )} '${cmd.tooltip}')`;
-}
-
-function renderHoverActions(actions: ra.CommandLinkGroup[]): vscode.MarkdownString {
-    const text = actions
-        .map(
-            (group) =>
-                (group.title ? group.title + " " : "") +
-                group.commands.map(renderCommand).join(" | "),
-        )
-        .join(" | ");
-
-    const result = new vscode.MarkdownString(text);
-    result.isTrusted = true;
-    return result;
-}
-
 export async function createClient(
     traceOutputChannel: vscode.OutputChannel,
     outputChannel: vscode.OutputChannel,
@@ -450,3 +390,32 @@ function isCodeActionWithoutEditsAndCommands(value: any): boolean {
         candidate.command === void 0
     );
 }
+
+// Command URIs have a form of command:command-name?arguments, where
+// arguments is a percent-encoded array of data we want to pass along to
+// the command function. For "Show References" this is a list of all file
+// URIs with locations of every reference, and it can get quite long.
+// So long in fact that it will fail rendering inside an `a` tag so we need
+// to proxy around that. We store the last hover's reference command link
+// here, as only one hover can be active at a time, and we don't need to
+// keep a history of these.
+export let HOVER_REFERENCE_COMMAND: ra.CommandLink | undefined = undefined;
+
+function renderCommand(cmd: ra.CommandLink): string {
+    HOVER_REFERENCE_COMMAND = cmd;
+    return `[${cmd.title}](command:rust-analyzer.hoverRefCommandProxy '${cmd.tooltip}')`;
+}
+
+function renderHoverActions(actions: ra.CommandLinkGroup[]): vscode.MarkdownString {
+    const text = actions
+        .map(
+            (group) =>
+                (group.title ? group.title + " " : "") +
+                group.commands.map(renderCommand).join(" | "),
+        )
+        .join(" | ");
+
+    const result = new vscode.MarkdownString(text);
+    result.isTrusted = true;
+    return result;
+}
diff --git a/src/tools/rust-analyzer/editors/code/src/commands.ts b/src/tools/rust-analyzer/editors/code/src/commands.ts
index 5048f820e4c..c226aefeab4 100644
--- a/src/tools/rust-analyzer/editors/code/src/commands.ts
+++ b/src/tools/rust-analyzer/editors/code/src/commands.ts
@@ -24,12 +24,12 @@ import {
     isRustEditor,
     type RustEditor,
     type RustDocument,
+    unwrapUndefinable,
 } from "./util";
 import { startDebugSession, makeDebugConfig } from "./debug";
 import type { LanguageClient } from "vscode-languageclient/node";
-import { LINKED_COMMANDS } from "./client";
+import { HOVER_REFERENCE_COMMAND } from "./client";
 import type { DependencyId } from "./dependencies_provider";
-import { unwrapUndefinable } from "./undefinable";
 import { log } from "./util";
 
 export * from "./ast_inspector";
@@ -1196,11 +1196,10 @@ export function newDebugConfig(ctx: CtxInit): Cmd {
     };
 }
 
-export function linkToCommand(_: Ctx): Cmd {
-    return async (commandId: string) => {
-        const link = LINKED_COMMANDS.get(commandId);
-        if (link) {
-            const { command, arguments: args = [] } = link;
+export function hoverRefCommandProxy(_: Ctx): Cmd {
+    return async () => {
+        if (HOVER_REFERENCE_COMMAND) {
+            const { command, arguments: args = [] } = HOVER_REFERENCE_COMMAND;
             await vscode.commands.executeCommand(command, ...args);
         }
     };
diff --git a/src/tools/rust-analyzer/editors/code/src/config.ts b/src/tools/rust-analyzer/editors/code/src/config.ts
index e676bc0826c..1931cfe3813 100644
--- a/src/tools/rust-analyzer/editors/code/src/config.ts
+++ b/src/tools/rust-analyzer/editors/code/src/config.ts
@@ -2,9 +2,7 @@ import * as Is from "vscode-languageclient/lib/common/utils/is";
 import * as os from "os";
 import * as path from "path";
 import * as vscode from "vscode";
-import type { Env } from "./client";
-import { log } from "./util";
-import { expectNotUndefined, unwrapUndefinable } from "./undefinable";
+import { type Env, log, unwrapUndefinable, expectNotUndefined } from "./util";
 import type { JsonProject } from "./rust_project";
 
 export type RunnableEnvCfgItem = {
diff --git a/src/tools/rust-analyzer/editors/code/src/debug.ts b/src/tools/rust-analyzer/editors/code/src/debug.ts
index eef2f6f4ee2..58fe1df51f4 100644
--- a/src/tools/rust-analyzer/editors/code/src/debug.ts
+++ b/src/tools/rust-analyzer/editors/code/src/debug.ts
@@ -6,8 +6,7 @@ import type * as ra from "./lsp_ext";
 import { Cargo, getRustcId, getSysroot } from "./toolchain";
 import type { Ctx } from "./ctx";
 import { prepareEnv } from "./run";
-import { unwrapUndefinable } from "./undefinable";
-import { isCargoRunnableArgs } from "./util";
+import { isCargoRunnableArgs, unwrapUndefinable } from "./util";
 
 const debugOutput = vscode.window.createOutputChannel("Debug");
 type DebugConfigProvider = (
@@ -136,7 +135,7 @@ async function getDebugConfiguration(
     const workspaceQualifier = isMultiFolderWorkspace ? `:${workspace.name}` : "";
     function simplifyPath(p: string): string {
         // see https://github.com/rust-lang/rust-analyzer/pull/5513#issuecomment-663458818 for why this is needed
-        return path.normalize(p).replace(wsFolder, "${workspaceFolder" + workspaceQualifier + "}");
+        return path.normalize(p).replace(wsFolder, `\${workspaceFolder${workspaceQualifier}}`);
     }
 
     const env = prepareEnv(runnable.label, runnableArgs, ctx.config.runnablesExtraEnv);
diff --git a/src/tools/rust-analyzer/editors/code/src/dependencies_provider.ts b/src/tools/rust-analyzer/editors/code/src/dependencies_provider.ts
index 863ace07801..203ef5cc85e 100644
--- a/src/tools/rust-analyzer/editors/code/src/dependencies_provider.ts
+++ b/src/tools/rust-analyzer/editors/code/src/dependencies_provider.ts
@@ -4,7 +4,7 @@ import * as fs from "fs";
 import type { CtxInit } from "./ctx";
 import * as ra from "./lsp_ext";
 import type { FetchDependencyListResult } from "./lsp_ext";
-import { unwrapUndefinable } from "./undefinable";
+import { unwrapUndefinable } from "./util";
 
 export class RustDependenciesProvider
     implements vscode.TreeDataProvider<Dependency | DependencyFile>
diff --git a/src/tools/rust-analyzer/editors/code/src/diagnostics.ts b/src/tools/rust-analyzer/editors/code/src/diagnostics.ts
index e31a1cdcef9..9fb2993d12f 100644
--- a/src/tools/rust-analyzer/editors/code/src/diagnostics.ts
+++ b/src/tools/rust-analyzer/editors/code/src/diagnostics.ts
@@ -8,7 +8,7 @@ import {
     window,
 } from "vscode";
 import type { Ctx } from "./ctx";
-import { unwrapUndefinable } from "./undefinable";
+import { unwrapUndefinable } from "./util";
 
 export const URI_SCHEME = "rust-analyzer-diagnostics-view";
 
diff --git a/src/tools/rust-analyzer/editors/code/src/main.ts b/src/tools/rust-analyzer/editors/code/src/main.ts
index 0af58fd7812..788f9a0c148 100644
--- a/src/tools/rust-analyzer/editors/code/src/main.ts
+++ b/src/tools/rust-analyzer/editors/code/src/main.ts
@@ -182,7 +182,7 @@ function createCommands(): Record<string, CommandFactory> {
         applySnippetWorkspaceEdit: { enabled: commands.applySnippetWorkspaceEditCommand },
         debugSingle: { enabled: commands.debugSingle },
         gotoLocation: { enabled: commands.gotoLocation },
-        linkToCommand: { enabled: commands.linkToCommand },
+        hoverRefCommandProxy: { enabled: commands.hoverRefCommandProxy },
         resolveCodeAction: { enabled: commands.resolveCodeAction },
         runSingle: { enabled: commands.runSingle },
         showReferences: { enabled: commands.showReferences },
diff --git a/src/tools/rust-analyzer/editors/code/src/nullable.ts b/src/tools/rust-analyzer/editors/code/src/nullable.ts
deleted file mode 100644
index e973e162907..00000000000
--- a/src/tools/rust-analyzer/editors/code/src/nullable.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-export type NotNull<T> = T extends null ? never : T;
-
-export type Nullable<T> = T | null;
-
-function isNotNull<T>(input: Nullable<T>): input is NotNull<T> {
-    return input !== null;
-}
-
-function expectNotNull<T>(input: Nullable<T>, msg: string): NotNull<T> {
-    if (isNotNull(input)) {
-        return input;
-    }
-
-    throw new TypeError(msg);
-}
-
-export function unwrapNullable<T>(input: Nullable<T>): NotNull<T> {
-    return expectNotNull(input, `unwrapping \`null\``);
-}
diff --git a/src/tools/rust-analyzer/editors/code/src/run.ts b/src/tools/rust-analyzer/editors/code/src/run.ts
index 1206137b6f4..7a9049af0de 100644
--- a/src/tools/rust-analyzer/editors/code/src/run.ts
+++ b/src/tools/rust-analyzer/editors/code/src/run.ts
@@ -6,9 +6,8 @@ import * as tasks from "./tasks";
 import type { CtxInit } from "./ctx";
 import { makeDebugConfig } from "./debug";
 import type { Config, RunnableEnvCfg, RunnableEnvCfgItem } from "./config";
-import { unwrapUndefinable } from "./undefinable";
 import type { LanguageClient } from "vscode-languageclient/node";
-import type { RustEditor } from "./util";
+import { unwrapUndefinable, type RustEditor } from "./util";
 import * as toolchain from "./toolchain";
 
 const quickPickButtons = [
@@ -148,8 +147,7 @@ export async function createTaskFromRunnable(
         };
     }
 
-    // eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
-    const target = vscode.workspace.workspaceFolders![0]; // safe, see main activate()
+    const target = vscode.workspace.workspaceFolders?.[0];
     const exec = await tasks.targetToExecution(definition, config.cargoRunner, true);
     const task = await tasks.buildRustTask(
         target,
diff --git a/src/tools/rust-analyzer/editors/code/src/snippets.ts b/src/tools/rust-analyzer/editors/code/src/snippets.ts
index b3982bdf2be..a469a9cd1f4 100644
--- a/src/tools/rust-analyzer/editors/code/src/snippets.ts
+++ b/src/tools/rust-analyzer/editors/code/src/snippets.ts
@@ -1,7 +1,6 @@
 import * as vscode from "vscode";
 
-import { assert } from "./util";
-import { unwrapUndefinable } from "./undefinable";
+import { assert, unwrapUndefinable } from "./util";
 
 export type SnippetTextDocumentEdit = [vscode.Uri, (vscode.TextEdit | vscode.SnippetTextEdit)[]];
 
diff --git a/src/tools/rust-analyzer/editors/code/src/tasks.ts b/src/tools/rust-analyzer/editors/code/src/tasks.ts
index 870b1ffb71c..6f4fbf91889 100644
--- a/src/tools/rust-analyzer/editors/code/src/tasks.ts
+++ b/src/tools/rust-analyzer/editors/code/src/tasks.ts
@@ -1,7 +1,6 @@
 import * as vscode from "vscode";
 import type { Config } from "./config";
-import { log } from "./util";
-import { unwrapUndefinable } from "./undefinable";
+import { log, unwrapUndefinable } from "./util";
 import * as toolchain from "./toolchain";
 
 // This ends up as the `type` key in tasks.json. RLS also uses `cargo` and
diff --git a/src/tools/rust-analyzer/editors/code/src/toolchain.ts b/src/tools/rust-analyzer/editors/code/src/toolchain.ts
index 060b0245d2c..a48d2d90cce 100644
--- a/src/tools/rust-analyzer/editors/code/src/toolchain.ts
+++ b/src/tools/rust-analyzer/editors/code/src/toolchain.ts
@@ -3,9 +3,7 @@ import * as os from "os";
 import * as path from "path";
 import * as readline from "readline";
 import * as vscode from "vscode";
-import { execute, log, memoizeAsync } from "./util";
-import { unwrapNullable } from "./nullable";
-import { unwrapUndefinable } from "./undefinable";
+import { execute, log, memoizeAsync, unwrapNullable, unwrapUndefinable } from "./util";
 
 interface CompilationArtifact {
     fileName: string;
@@ -157,7 +155,7 @@ export function cargoPath(): Promise<string> {
 }
 
 /** Mirrors `toolchain::get_path_for_executable()` implementation */
-export const getPathForExecutable = memoizeAsync(
+const getPathForExecutable = memoizeAsync(
     // We apply caching to decrease file-system interactions
     async (executableName: "cargo" | "rustc" | "rustup"): Promise<string> => {
         {
diff --git a/src/tools/rust-analyzer/editors/code/src/undefinable.ts b/src/tools/rust-analyzer/editors/code/src/undefinable.ts
deleted file mode 100644
index 813bac5a123..00000000000
--- a/src/tools/rust-analyzer/editors/code/src/undefinable.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-export type NotUndefined<T> = T extends undefined ? never : T;
-
-export type Undefinable<T> = T | undefined;
-
-function isNotUndefined<T>(input: Undefinable<T>): input is NotUndefined<T> {
-    return input !== undefined;
-}
-
-export function expectNotUndefined<T>(input: Undefinable<T>, msg: string): NotUndefined<T> {
-    if (isNotUndefined(input)) {
-        return input;
-    }
-
-    throw new TypeError(msg);
-}
-
-export function unwrapUndefinable<T>(input: Undefinable<T>): NotUndefined<T> {
-    return expectNotUndefined(input, `unwrapping \`undefined\``);
-}
diff --git a/src/tools/rust-analyzer/editors/code/src/util.ts b/src/tools/rust-analyzer/editors/code/src/util.ts
index 868cb2b7807..dd1cbe38ff9 100644
--- a/src/tools/rust-analyzer/editors/code/src/util.ts
+++ b/src/tools/rust-analyzer/editors/code/src/util.ts
@@ -1,9 +1,8 @@
 import * as vscode from "vscode";
 import { strict as nativeAssert } from "assert";
-import { exec, type ExecOptions, spawnSync } from "child_process";
+import { exec, type ExecOptions } from "child_process";
 import { inspect } from "util";
 import type { CargoRunnableArgs, ShellRunnableArgs } from "./lsp_ext";
-import type { Env } from "./client";
 
 export function assert(condition: boolean, explanation: string): asserts condition {
     try {
@@ -14,6 +13,10 @@ export function assert(condition: boolean, explanation: string): asserts conditi
     }
 }
 
+export type Env = {
+    [name: string]: string;
+};
+
 export const log = new (class {
     private enabled = true;
     private readonly output = vscode.window.createOutputChannel("Rust Analyzer Client");
@@ -101,20 +104,6 @@ export function isDocumentInWorkspace(document: RustDocument): boolean {
     return false;
 }
 
-export function isValidExecutable(path: string, extraEnv: Env): boolean {
-    log.debug("Checking availability of a binary at", path);
-
-    const res = spawnSync(path, ["--version"], {
-        encoding: "utf8",
-        env: { ...process.env, ...extraEnv },
-    });
-
-    const printOutput = res.error ? log.warn : log.info;
-    printOutput(path, "--version:", res);
-
-    return res.status === 0;
-}
-
 /** Sets ['when'](https://code.visualstudio.com/docs/getstarted/keybindings#_when-clause-contexts) clause contexts */
 export function setContextValue(key: string, value: any): Thenable<void> {
     return vscode.commands.executeCommand("setContext", key, value);
@@ -206,3 +195,42 @@ export class LazyOutputChannel implements vscode.OutputChannel {
         }
     }
 }
+
+export type NotNull<T> = T extends null ? never : T;
+
+export type Nullable<T> = T | null;
+
+function isNotNull<T>(input: Nullable<T>): input is NotNull<T> {
+    return input !== null;
+}
+
+function expectNotNull<T>(input: Nullable<T>, msg: string): NotNull<T> {
+    if (isNotNull(input)) {
+        return input;
+    }
+
+    throw new TypeError(msg);
+}
+
+export function unwrapNullable<T>(input: Nullable<T>): NotNull<T> {
+    return expectNotNull(input, `unwrapping \`null\``);
+}
+export type NotUndefined<T> = T extends undefined ? never : T;
+
+export type Undefinable<T> = T | undefined;
+
+function isNotUndefined<T>(input: Undefinable<T>): input is NotUndefined<T> {
+    return input !== undefined;
+}
+
+export function expectNotUndefined<T>(input: Undefinable<T>, msg: string): NotUndefined<T> {
+    if (isNotUndefined(input)) {
+        return input;
+    }
+
+    throw new TypeError(msg);
+}
+
+export function unwrapUndefinable<T>(input: Undefinable<T>): NotUndefined<T> {
+    return expectNotUndefined(input, `unwrapping \`undefined\``);
+}