Warn Users When a Local Regal Binary for Development Isn't Found

src/binaries/resolver.ts

@@ -9,6 +9,8 @@ import { BinaryConfig, BinaryInfo } from "./types";
 export function resolveBinary(config: BinaryConfig, fallbackPath?: string): BinaryInfo {
   let path = vscode.workspace.getConfiguration("opa.dependency_paths").get<string>(config.configKey);
 
+  let configuredOriginalPath: string | undefined;
+
   if (path?.trim()) {
     const originalPath = path;
     path = replaceWorkspaceFolderPathVariable(path);
@@ -27,6 +29,8 @@ export function resolveBinary(config: BinaryConfig, fallbackPath?: string): Bina
         ...(versionInfo.error && { error: versionInfo.error }),
       };
     }
+
+    configuredOriginalPath = originalPath;
   }
 
   const systemPath = fallbackPath || config.configKey;
@@ -36,12 +40,46 @@ export function resolveBinary(config: BinaryConfig, fallbackPath?: string): Bina
       path: systemPath,
       source: "system",
       version: versionInfo.version,
+      ...(configuredOriginalPath && {
+        originalPath: configuredOriginalPath,
+        configuredPathMissing: true,
+      }),
       ...(versionInfo.error && { error: versionInfo.error }),
     };
   }
 
   return {
     source: "missing",
     version: "missing",
+    ...(configuredOriginalPath && {
+      originalPath: configuredOriginalPath,
+      configuredPathMissing: true,
+    }),
   };
 }
+
+// warnConfiguredPathMissing logs to the output channel and shows a popup
+// indicating the configured binary path didn't exist on disk. Callers should
+// gate this on binaryInfo.configuredPathMissing being set.
+export function warnConfiguredPathMissing(
+  config: BinaryConfig,
+  binaryInfo: BinaryInfo,
+  outputChannel: vscode.OutputChannel,
+): void {
+  const inspected = vscode.workspace
+    .getConfiguration("opa.dependency_paths")
+    .inspect<string>(config.configKey);
+  const sourceDetail = inspected?.workspaceValue
+    ? "workspace settings (.vscode/settings.json)"
+    : "user settings";
+
+  outputChannel.appendLine(
+    `${config.name}: configured path '${binaryInfo.originalPath}' from ${sourceDetail} not found; falling back to ${
+      binaryInfo.source === "system" ? "system PATH" : "no binary available"
+    }.`,
+  );
+
+  vscode.window.showWarningMessage(
+    `${config.name} binary not found at configured path '${binaryInfo.originalPath}' (from ${sourceDetail}).`,
+  );
+}

src/binaries/types.ts

@@ -18,6 +18,7 @@ export interface BinaryInfo {
   path?: string;
   source: "configured" | "system" | "missing";
   originalPath?: string;
+  configuredPathMissing?: boolean;
   version: string;
   error?: string;
 }

src/extension.ts

@@ -4,7 +4,14 @@ import * as fs from "fs";
 import * as path from "path";
 import * as vscode from "vscode";
 
-import { BinaryConfig, installBinary, OPA_CONFIG, REGAL_CONFIG, resolveBinary } from "./binaries";
+import {
+  BinaryConfig,
+  installBinary,
+  OPA_CONFIG,
+  REGAL_CONFIG,
+  resolveBinary,
+  warnConfiguredPathMissing,
+} from "./binaries";
 import { activateDebugger } from "./da/activate";
 import {
   activateRegal,
@@ -144,6 +151,12 @@ export async function activate(context: vscode.ExtensionContext) {
   // check for missing binaries and prompt to install them
   checkMissingBinaries();
 
+  // warn if the configured opa.dependency_paths.opa points to a non-existent file
+  const opaBinaryInfo = resolveBinary(OPA_CONFIG, "opa");
+  if (opaBinaryInfo.configuredPathMissing) {
+    warnConfiguredPathMissing(OPA_CONFIG, opaBinaryInfo, opaOutputChannel);
+  }
+
   // start Regal language server and wire up the client
   const result = await activateRegal(regalOptions);
   if (result) {

src/ls/clients/regal.ts

@@ -13,7 +13,7 @@ import {
   ServerOptions,
   State,
 } from "vscode-languageclient/node";
-import { REGAL_CONFIG, resolveBinary } from "../../binaries";
+import { REGAL_CONFIG, resolveBinary, warnConfiguredPathMissing } from "../../binaries";
 import {
   evalResultDecorationType,
   evalResultTargetSuccessDecorationType,
@@ -155,6 +155,10 @@ export async function activateRegal(
 
   const binaryInfo = resolveBinary(REGAL_CONFIG, "regal");
 
+  if (binaryInfo.configuredPathMissing) {
+    warnConfiguredPathMissing(REGAL_CONFIG, binaryInfo, opaOutputChannel);
+  }
+
   // Validate binary availability
   if (!binaryInfo.path) {
     clientLock = false;