feat(lsp): auto-import types with 'import type' (#25662)

3 files changed, 46 insertions, 56 deletions

diff --git a/cli/lsp/tsc.rs b/cli/lsp/tsc.rs
index 0decef396..6d3e1317b 100644
--- a/cli/lsp/tsc.rs
+++ b/cli/lsp/tsc.rs
@@ -6154,7 +6154,7 @@ mod tests {
     let change = changes.text_changes.first().unwrap();
     assert_eq!(
       change.new_text,
-      "import { someLongVariable } from './b.ts'\n"
+      "import type { someLongVariable } from './b.ts'\n"
     );
   }
 
diff --git a/cli/tsc/99_main_compiler.js b/cli/tsc/99_main_compiler.js
index 7fac8cd35..c5769168f 100644
--- a/cli/tsc/99_main_compiler.js
+++ b/cli/tsc/99_main_compiler.js
@@ -516,6 +516,7 @@ delete Object.prototype.__proto__;
   /** @typedef {{
    *    ls: ts.LanguageService & { [k:string]: any },
    *    compilerOptions: ts.CompilerOptions,
+   *    forceEnabledVerbatimModuleSyntax: boolean,
    *  }} LanguageServiceEntry */
   /** @type {{ unscoped: LanguageServiceEntry, byScope: Map<string, LanguageServiceEntry> }} */
   const languageServiceEntries = {
@@ -1025,7 +1026,7 @@ delete Object.prototype.__proto__;
         : ts.sortAndDeduplicateDiagnostics(
           checkFiles.map((s) => program.getSemanticDiagnostics(s)).flat(),
         )),
-    ].filter(filterMapDiagnostic);
+    ].filter(filterMapDiagnostic.bind(null, false));
 
     // emit the tsbuildinfo file
     // @ts-ignore: emitBuildInfo is not exposed (https://github.com/microsoft/TypeScript/issues/49871)
@@ -1040,11 +1041,28 @@ delete Object.prototype.__proto__;
     debug("<<< exec stop");
   }
 
-  /** @param {ts.Diagnostic} diagnostic */
-  function filterMapDiagnostic(diagnostic) {
+  /**
+   * @param {boolean} isLsp
+   * @param {ts.Diagnostic} diagnostic
+   */
+  function filterMapDiagnostic(isLsp, diagnostic) {
     if (IGNORED_DIAGNOSTICS.includes(diagnostic.code)) {
       return false;
     }
+    if (isLsp) {
+      // TS1484: `...` is a type and must be imported using a type-only import when 'verbatimModuleSyntax' is enabled.
+      // We force-enable `verbatimModuleSyntax` in the LSP so the `type`
+      // modifier is used when auto-importing types. But we don't want this
+      // diagnostic unless it was explicitly enabled by the user.
+      if (diagnostic.code == 1484) {
+        const entry = (lastRequestScope
+          ? languageServiceEntries.byScope.get(lastRequestScope)
+          : null) ?? languageServiceEntries.unscoped;
+        if (entry.forceEnabledVerbatimModuleSyntax) {
+          return false;
+        }
+      }
+    }
     // make the diagnostic for using an `export =` in an es module a warning
     if (diagnostic.code === 1203) {
       diagnostic.category = ts.DiagnosticCategory.Warning;
@@ -1140,10 +1158,12 @@ delete Object.prototype.__proto__;
         "strict": true,
         "target": "esnext",
         "useDefineForClassFields": true,
+        "verbatimModuleSyntax": true,
         "jsx": "react",
         "jsxFactory": "React.createElement",
         "jsxFragmentFactory": "React.Fragment",
       }),
+      forceEnabledVerbatimModuleSyntax: true,
     };
     setLogDebug(enableDebugLogging, "TSLS");
     debug("serverInit()");
@@ -1209,8 +1229,17 @@ delete Object.prototype.__proto__;
           const ls = oldEntry
             ? oldEntry.ls
             : ts.createLanguageService(host, documentRegistry);
+          let forceEnabledVerbatimModuleSyntax = false;
+          if (!config["verbatimModuleSyntax"]) {
+            config["verbatimModuleSyntax"] = true;
+            forceEnabledVerbatimModuleSyntax = true;
+          }
           const compilerOptions = lspTsConfigToCompilerOptions(config);
-          newByScope.set(scope, { ls, compilerOptions });
+          newByScope.set(scope, {
+            ls,
+            compilerOptions,
+            forceEnabledVerbatimModuleSyntax,
+          });
           languageServiceEntries.byScope.delete(scope);
         }
         for (const oldEntry of languageServiceEntries.byScope.values()) {
@@ -1275,7 +1304,7 @@ delete Object.prototype.__proto__;
               ...ls.getSemanticDiagnostics(specifier),
               ...ls.getSuggestionDiagnostics(specifier),
               ...ls.getSyntacticDiagnostics(specifier),
-            ].filter(filterMapDiagnostic));
+            ].filter(filterMapDiagnostic.bind(null, true)));
           }
           return respond(id, diagnosticMap);
         } catch (e) {
diff --git a/tests/integration/lsp_tests.rs b/tests/integration/lsp_tests.rs
index b6cc71ec6..095cbee98 100644
--- a/tests/integration/lsp_tests.rs
+++ b/tests/integration/lsp_tests.rs
@@ -5659,7 +5659,7 @@ fn lsp_jsr_code_action_missing_declaration() {
                       "character": 6,
                     },
                   },
-                  "newText": "import { ReturnType } from \"jsr:@denotest/types-file/types\";\n",
+                  "newText": "import type { ReturnType } from \"jsr:@denotest/types-file/types\";\n",
                 },
                 {
                   "range": {
@@ -6150,7 +6150,7 @@ export class DuckConfig {
               "start": { "line": 0, "character": 0 },
               "end": { "line": 0, "character": 0 }
             },
-            "newText": "import { DuckConfigOptions } from \"./file02.ts\";\n\n"
+            "newText": "import type { DuckConfigOptions } from \"./file02.ts\";\n\n"
           }]
         }]
       }
@@ -6266,7 +6266,7 @@ export class DuckConfig {
               "start": { "line": 0, "character": 0 },
               "end": { "line": 0, "character": 0 }
             },
-            "newText": "import { DuckConfig } from \"./file01.ts\";\nimport { DuckConfigOptions } from \"./file02.ts\";\n\n"
+            "newText": "import { DuckConfig } from \"./file01.ts\";\nimport type { DuckConfigOptions } from \"./file02.ts\";\n\n"
           }]
         }]
       },
@@ -6343,7 +6343,7 @@ fn lsp_code_actions_imports_dts() {
               "start": { "line": 0, "character": 0 },
               "end": { "line": 0, "character": 0 },
             },
-            "newText": "import { SomeType } from \"./decl.d.ts\";\n",
+            "newText": "import type { SomeType } from \"./decl.d.ts\";\n",
           }],
         }],
       },
@@ -6663,7 +6663,7 @@ fn lsp_code_actions_imports_respects_fmt_config() {
               "start": { "line": 0, "character": 0 },
               "end": { "line": 0, "character": 0 }
             },
-            "newText": "import { DuckConfigOptions } from './file01.ts'\n"
+            "newText": "import type { DuckConfigOptions } from './file01.ts'\n"
           }]
         }]
       }
@@ -6716,7 +6716,7 @@ fn lsp_code_actions_imports_respects_fmt_config() {
               "start": { "line": 0, "character": 0 },
               "end": { "line": 0, "character": 0 }
             },
-            "newText": "import { DuckConfigOptions } from './file01.ts'\n"
+            "newText": "import type { DuckConfigOptions } from './file01.ts'\n"
           }]
         }]
       },
@@ -6816,7 +6816,7 @@ fn lsp_quote_style_from_workspace_settings() {
               "start": { "line": 0, "character": 0 },
               "end": { "line": 0, "character": 0 },
             },
-            "newText": "import { DuckConfigOptions } from './file01.ts';\n",
+            "newText": "import type { DuckConfigOptions } from './file01.ts';\n",
           }],
         }],
       },
@@ -6860,7 +6860,7 @@ fn lsp_quote_style_from_workspace_settings() {
               "start": { "line": 0, "character": 0 },
               "end": { "line": 0, "character": 0 },
             },
-            "newText": "import { DuckConfigOptions } from \"./file01.ts\";\n",
+            "newText": "import type { DuckConfigOptions } from \"./file01.ts\";\n",
           }],
         }],
       },
@@ -7246,12 +7246,12 @@ fn lsp_completions_auto_import() {
       "uri": "file:///a/file.ts",
       "languageId": "typescript",
       "version": 1,
-      "text": "export {};\n\n",
+      "text": "const result = add(1, 2);\n",
     }
   }));
   let list = client.get_completion_list(
     "file:///a/file.ts",
-    (2, 0),
+    (0, 18),
     json!({ "triggerKind": 1 }),
   );
   assert!(!list.is_incomplete);
@@ -7259,46 +7259,7 @@ fn lsp_completions_auto_import() {
   let Some(item) = item else {
     panic!("completions items missing 'add' symbol");
   };
-  let mut item_value = serde_json::to_value(item).unwrap();
-  item_value["data"]["tsc"]["data"]["exportMapKey"] =
-    serde_json::Value::String("".to_string());
-
-  let req = json!({
-    "label": "add",
-    "labelDetails": {
-      "description": "./🦕.ts",
-    },
-    "kind": 3,
-    "sortText": "￿16_0",
-    "commitCharacters": [
-      ".",
-      ",",
-      ";",
-      "("
-    ],
-    "data": {
-      "tsc": {
-        "specifier": "file:///a/file.ts",
-        "position": 12,
-        "name": "add",
-        "source": "./%F0%9F%A6%95.ts",
-         "specifierRewrite": [
-           "./%F0%9F%A6%95.ts",
-           "./🦕.ts",
-         ],
-        "data": {
-          "exportName": "add",
-          "exportMapKey": "",
-          "moduleSpecifier": "./%F0%9F%A6%95.ts",
-          "fileName": "file:///a/%F0%9F%A6%95.ts"
-        },
-        "useCodeSnippet": false
-      }
-    }
-  });
-  assert_eq!(item_value, req);
-
-  let res = client.write_request("completionItem/resolve", req);
+  let res = client.write_request("completionItem/resolve", json!(item));
   assert_eq!(
     res,
     json!({