title: TS2585: 'Promise' only refers to a type, but is being used as a value here
body: <p>I'm getting the following error</p>
  
  <blockquote>
    <p>node_modules/rxjs/internal/Observable.d.ts:82:59 - error TS2585: 'Promise' only refers to a type, but is being used as a value here. Do you need to change your target library? Try changing the <code>lib</code> compiler option to es2015 or later.</p>
  </blockquote>
  
  <p>Formatted it looks like this,</p>
  
  <pre><code>node_modules/rxjs/internal/Observable.d.ts:82:59 - error TS2585: 'Promise' only refers to a type, but is being used as a value here. Do you need to change your target library? Try changing the `lib` compiler option to es2015 or later.                                                                   
  
  82     toPromise&lt;T&gt;(this: Observable&lt;T&gt;, PromiseCtor: typeof Promise): Promise&lt;T&gt;;                                                                    
                                                               ~~~~~~~
  
  
  Found 1 error.
  </code></pre>
  
  <p>But the code I'm trying to run is right from the examples,</p>
  
  <pre><code>import { range } from 'rxjs';
  import { map, filter } from 'rxjs/operators';
  
  range(1, 200).pipe(
    filter(x =&gt; x % 2 === 1),
    map(x =&gt; x + x)
  ).subscribe(x =&gt; console.log(x));
  </code></pre>
  
  <p>I have in my <code>tsconfig.json</code></p>
  
  <pre><code>"target": "ES2018",                                                                                       
  "module": "es2015",   
  "lib": ["es2015"],
  </code></pre>
  
  <p>I'm running Rx.js 6.3.3, TypeScript 3.2.2 under Node v11.6.0. I've tried</p>
  
  <pre><code>npm i --save-dev  @types/es6-promise
  </code></pre>
  
  <p>and just about every combination of changing <code>lib</code> and <code>module</code></p>
  
  <p>My ts config is exactly this,</p>
  
  <pre><code>{
    "compilerOptions": {
      /* Basic Options */
      "target": "ES2016",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
      "module": "es2015",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
      "lib": ["es2016"],                             /* Specify library files to be included in the compilation. */
      // "allowJs": true,                       /* Allow javascript files to be compiled. */
      // "checkJs": true,                       /* Report errors in .js files. */
      // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
      // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
      // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
      // "sourceMap": true,                     /* Generates corresponding '.map' file. */
      // "outFile": "./",                       /* Concatenate and emit output to single file. */
      // "outDir": "./",                        /* Redirect output structure to the directory. */
      // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
      // "composite": true,                     /* Enable project compilation */
      // "removeComments": true,                /* Do not emit comments to output. */
      // "noEmit": true,                        /* Do not emit outputs. */
      // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
      // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
      // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
  
      /* Strict Type-Checking Options */
      "strict": true,                           /* Enable all strict type-checking options. */
      // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
      // "strictNullChecks": true,              /* Enable strict null checks. */
      // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
      // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
      // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
      // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
      // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
  
      /* Additional Checks */
      // "noUnusedLocals": true,                /* Report errors on unused locals. */
      // "noUnusedParameters": true,            /* Report errors on unused parameters. */
      // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
      // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
  
      /* Module Resolution Options */
      "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
      // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
      // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
      // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
      // "typeRoots": [],                       /* List of folders to include type definitions from. */
      // "types": [],                           /* Type declaration files to be included in compilation. */
      // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
      "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
      // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
  
      /* Source Map Options */
      // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
      // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
      // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
      // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
  
      /* Experimental Options */
      // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
      // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
    }
  }
  </code></pre>