use unresolved imports as a source of used typings (#11828)

src/services/jsTyping.ts

@@ -31,6 +31,17 @@ namespace ts.JsTyping {
 
     const EmptySafeList: Map<string> = createMap<string>();
 
+    /* @internal */
+    export const nodeCoreModuleList: ReadonlyArray<string> = [
+        "buffer", "querystring", "events", "http", "cluster",
+        "zlib", "os", "https", "punycode", "repl", "readline",
+        "vm", "child_process", "url", "dns", "net",
+        "dgram", "fs", "path", "string_decoder", "tls",
+        "crypto", "stream", "util", "assert", "tty", "domain",
+        "constants", "process", "v8", "timers", "console"];
+
+    const nodeCoreModules = arrayToMap(<string[]>nodeCoreModuleList, x => x);
+
     /**
      * @param host is the object providing I/O related operations.
      * @param fileNames are the file names that belong to the same project
@@ -46,7 +57,8 @@ namespace ts.JsTyping {
         projectRootPath: Path,
         safeListPath: Path,
         packageNameToTypingLocation: Map<string>,
-        typingOptions: TypingOptions):
+        typingOptions: TypingOptions,
+        unresolvedImports: ReadonlyArray<string>):
         { cachedTypingPaths: string[], newTypingNames: string[], filesToWatch: string[] } {
 
         // A typing name to typing file path mapping
@@ -92,6 +104,15 @@ namespace ts.JsTyping {
         }
         getTypingNamesFromSourceFileNames(fileNames);
 
+        // add typings for unresolved imports
+        if (unresolvedImports) {
+            for (const moduleId of unresolvedImports) {
+                const typingName = moduleId in nodeCoreModules ? "node" : moduleId;
+                if (!(typingName in inferredTypings)) {
+                    inferredTypings[typingName] = undefined;
+                }
+            }
+        }
         // Add the cached typing locations for inferred typings that are already installed
         for (const name in packageNameToTypingLocation) {
             if (name in inferredTypings && !inferredTypings[name]) {

src/services/shims.ts

@@ -1168,7 +1168,8 @@ namespace ts {
                     toPath(info.projectRootPath, info.projectRootPath, getCanonicalFileName),
                     toPath(info.safeListPath, info.safeListPath, getCanonicalFileName),
                     info.packageNameToTypingLocation,
-                    info.typingOptions);
+                    info.typingOptions,
+                    info.unresolvedImports);
             });
         }
     }