Deprecate {{partial}}

packages/@ember/-internals/glimmer/index.ts

@@ -340,6 +340,7 @@
   @method partial
   @for Ember.Templates.helpers
   @param {String} partialName The name of the template to render minus the leading underscore.
+  @deprecated Use a component instead
   @public
 */
 

packages/@ember/-internals/glimmer/lib/resolver.ts

@@ -1,13 +1,15 @@
 import { privatize as P } from '@ember/-internals/container';
 import { ENV } from '@ember/-internals/environment';
 import { Factory, FactoryClass, LookupOptions, Owner } from '@ember/-internals/owner';
-import { lookupPartial, OwnedTemplateMeta } from '@ember/-internals/views';
+import { OwnedTemplateMeta } from '@ember/-internals/views';
 import {
   EMBER_GLIMMER_SET_COMPONENT_TEMPLATE,
   EMBER_MODULE_UNIFICATION,
 } from '@ember/canary-features';
 import { isTemplateOnlyComponent } from '@ember/component/template-only';
-import { assert } from '@ember/debug';
+import { assert, deprecate } from '@ember/debug';
+import { PARTIALS } from '@ember/deprecated-features';
+import EmberError from '@ember/error';
 import { _instrumentStart } from '@ember/instrumentation';
 import {
   ComponentDefinition,
@@ -176,6 +178,62 @@ function lookupComponent(owner: Owner, name: string, options: LookupOptions): Op
   return lookupComponentPair(owner, name);
 }
 
+let lookupPartial: { templateName: string; owner: Owner } | any;
+let templateFor: { owner: Owner; underscored: string; name: string } | any;
+let parseUnderscoredName: { templateName: string } | any;
+
+if (PARTIALS) {
+  lookupPartial = function(templateName: string, owner: Owner) {
+    deprecate(
+      `The use of \`{{partial}}\` is deprecated, please refactor the "${templateName}" partial to a component`,
+      false,
+      {
+        id: 'ember-views.partial',
+        until: '4.0.0',
+        url: 'https://deprecations.emberjs.com/v3.x#toc_ember-views-partial',
+      }
+    );
+
+    if (templateName === null) {
+      return;
+    }
+
+    let template = templateFor(owner, parseUnderscoredName(templateName), templateName);
+
+    assert(`Unable to find partial with name "${templateName}"`, Boolean(template));
+
+    return template;
+  };
+
+  templateFor = function(owner: any, underscored: string, name: string) {
+    if (PARTIALS) {
+      if (!name) {
+        return;
+      }
+      assert(`templateNames are not allowed to contain periods: ${name}`, name.indexOf('.') === -1);
+
+      if (!owner) {
+        throw new EmberError(
+          'Container was not found when looking up a views template. ' +
+            'This is most likely due to manually instantiating an Ember.View. ' +
+            'See: http://git.io/EKPpnA'
+        );
+      }
+
+      return owner.lookup(`template:${underscored}`) || owner.lookup(`template:${name}`);
+    }
+  };
+
+  parseUnderscoredName = function(templateName: string) {
+    let nameParts = templateName.split('/');
+    let lastPart = nameParts[nameParts.length - 1];
+
+    nameParts[nameParts.length - 1] = `_${lastPart}`;
+
+    return nameParts.join('/');
+  };
+}
+
 interface IBuiltInHelpers {
   [name: string]: Helper | undefined;
 }
@@ -306,8 +364,12 @@ export default class RuntimeResolver implements IRuntimeResolver<OwnedTemplateMe
    * Called by CompileTimeLookup to lookup partial
    */
   lookupPartial(name: string, meta: OwnedTemplateMeta): Option<number> {
-    let partial = this._lookupPartial(name, meta);
-    return this.handle(partial);
+    if (PARTIALS) {
+      let partial = this._lookupPartial(name, meta);
+      return this.handle(partial);
+    } else {
+      return null;
+    }
   }
 
   // end CompileTimeLookup

packages/@ember/-internals/glimmer/tests/integration/application/engine-test.js

@@ -251,6 +251,10 @@ moduleFor(
     }
 
     ['@test attrs in an engine']() {
+      expectDeprecation(
+        `The use of \`{{partial}}\` is deprecated, please refactor the "troll" partial to a component`
+      );
+
       this.setupEngineWithAttrs([]);
 
       return this.visit('/').then(() => {
@@ -431,7 +435,11 @@ moduleFor(
     }
 
     ['@test visit() with partials in routable engine'](assert) {
-      assert.expect(2);
+      assert.expect(3);
+
+      expectDeprecation(
+        `The use of \`{{partial}}\` is deprecated, please refactor the "foo" partial to a component`
+      );
 
       let hooks = [];
 
@@ -449,7 +457,11 @@ moduleFor(
     }
 
     ['@test visit() with partials in non-routable engine'](assert) {
-      assert.expect(2);
+      assert.expect(3);
+
+      expectDeprecation(
+        `The use of \`{{partial}}\` is deprecated, please refactor the "foo" partial to a component`
+      );
 
       let hooks = [];
 

packages/@ember/-internals/glimmer/tests/integration/components/curly-components-test.js

@@ -760,7 +760,9 @@ moduleFor(
         template: '{{partial "partialWithYield"}} - In component',
       });
 
-      this.render('{{#foo-bar}}hello{{/foo-bar}}');
+      expectDeprecation(() => {
+        this.render('{{#foo-bar}}hello{{/foo-bar}}');
+      }, 'The use of `{{partial}}` is deprecated, please refactor the "partialWithYield" partial to a component');
 
       this.assertComponentElement(this.firstChild, {
         content: 'yielded: [hello] - In component',
@@ -780,7 +782,9 @@ moduleFor(
         template: '{{partial "partialWithYield"}} - In component',
       });
 
-      this.render('{{#foo-bar as |value|}}{{value}}{{/foo-bar}}');
+      expectDeprecation(() => {
+        this.render('{{#foo-bar as |value|}}{{value}}{{/foo-bar}}');
+      }, 'The use of `{{partial}}` is deprecated, please refactor the "partialWithYield" partial to a component');
 
       this.assertComponentElement(this.firstChild, {
         content: 'yielded: [hello] - In component',