Use import type in typescript for all imports (#4029)

Summary:
This makes the following change to typescript artifacts:

```diff
-import { ConcreteRequest, Query } from "relay-runtime";
+import type { ConcreteRequest, Query } from "relay-runtime";
 import type { FragmentRefs } from "relay-runtime";
```

Using the existing `useImportTypeSyntax` config.

As stated in the config, the `import type` syntax introduced in Typescript version 3.8 and prevents warnings from `importsNotUsedAsValues`. This setting also assists naive bundlers from taking a dependency on `relay-runtime`, when only the types are needed.

I kept this simple. Other paths for implementation would be
 - There's a mix of distinct typegen printers e.g. compiler/crates/relay-typegen/src/typescript.rs, and the inline use of conditionals on the language directly in compiler/crates/relay-compiler/src/artifact_content/content.rs. Consolidating these would allow sharing the existing `write_import_type` function
 - The imports could instead be consolidated and printed together, rather than potentially having multiple imports from the same file as it is now

Pull Request resolved: #4029

Test Plan:
Imported from GitHub, without a `Test Plan:` line.

Static Docs Site previews have moved into the custom phabricator field "Static Docs", and will no longer modify test plans after 5th October 2022.

Reviewed By: alunyov

Differential Revision: D38279030

Pulled By: alunyov

fbshipit-source-id: 1e252d2fe9041963a33d6dedecb4ac4b512628dd

compiler/crates/relay-compiler/src/artifact_content/content.rs

@@ -96,7 +96,7 @@ pub fn generate_updatable_query(
     }
 
     write_import_type_from(
-        &project_config.typegen_config.language,
+        project_config,
         &mut section,
         generated_types.imported_types,
         "relay-runtime",
@@ -260,7 +260,7 @@ pub fn generate_operation(
     }
 
     write_import_type_from(
-        &project_config.typegen_config.language,
+        project_config,
         &mut section,
         generated_types.imported_types,
         "relay-runtime",
@@ -426,7 +426,7 @@ pub fn generate_split_operation(
         writeln!(section, "/*::")?;
     }
     write_import_type_from(
-        &project_config.typegen_config.language,
+        project_config,
         &mut section,
         "NormalizationSplitOperation",
         "relay-runtime",
@@ -600,7 +600,7 @@ fn generate_read_only_fragment(
     }
 
     write_import_type_from(
-        &project_config.typegen_config.language,
+        project_config,
         &mut section,
         generated_types.imported_types,
         "relay-runtime",
@@ -790,15 +790,26 @@ fn generate_use_strict_section(language: &TypegenLanguage) -> Result<GenericSect
 }
 
 fn write_import_type_from(
-    language: &TypegenLanguage,
+    project_config: &ProjectConfig,
     section: &mut dyn Write,
     type_: &str,
     from: &str,
 ) -> FmtResult {
+    let language = &project_config.typegen_config.language;
     match language {
         TypegenLanguage::JavaScript => Ok(()),
         TypegenLanguage::Flow => writeln!(section, "import type {{ {} }} from '{}';", type_, from),
-        TypegenLanguage::TypeScript => writeln!(section, "import {{ {} }} from '{}';", type_, from),
+        TypegenLanguage::TypeScript => writeln!(
+            section,
+            "import {}{{ {} }} from '{}';",
+            if project_config.typegen_config.use_import_type_syntax {
+                "type "
+            } else {
+                ""
+            },
+            type_,
+            from
+        ),
     }
 }
 

compiler/crates/relay-typegen/tests/generate_typescript_import_syntax/fixtures/simple.expected

@@ -0,0 +1,24 @@
+==================================== INPUT ====================================
+fragment LinkedField on User {
+  name
+  profilePicture {
+    uri
+    width
+    height
+  }
+}
+==================================== OUTPUT ===================================
+import type { FragmentRefs } from "relay-runtime";
+export type LinkedField$data = {
+  readonly name: string | null;
+  readonly profilePicture: {
+    readonly height: number | null;
+    readonly uri: string | null;
+    readonly width: number | null;
+  } | null;
+  readonly " $fragmentType": "LinkedField";
+};
+export type LinkedField$key = {
+  readonly " $data"?: LinkedField$data;
+  readonly " $fragmentSpreads": FragmentRefs<"LinkedField">;
+};

compiler/crates/relay-typegen/tests/generate_typescript_import_syntax/fixtures/simple.graphql

@@ -0,0 +1,8 @@
+fragment LinkedField on User {
+  name
+  profilePicture {
+    uri
+    width
+    height
+  }
+}

compiler/crates/relay-typegen/tests/generate_typescript_import_syntax/mod.rs

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+use std::sync::Arc;
+
+use common::ConsoleLogger;
+use common::FeatureFlag;
+use common::FeatureFlags;
+use common::SourceLocationKey;
+use fixture_tests::Fixture;
+use fnv::FnvBuildHasher;
+use fnv::FnvHashMap;
+use graphql_ir::build;
+use graphql_ir::Program;
+use graphql_syntax::parse_executable;
+use indexmap::IndexMap;
+use intern::string_key::Intern;
+use relay_codegen::JsModuleFormat;
+use relay_config::CustomScalarType;
+use relay_config::CustomScalarTypeImport;
+use relay_config::ProjectConfig;
+use relay_test_schema::get_test_schema;
+use relay_test_schema::get_test_schema_with_extensions;
+use relay_transforms::apply_transforms;
+use relay_typegen::FragmentLocations;
+use relay_typegen::TypegenConfig;
+use relay_typegen::TypegenLanguage;
+use relay_typegen::{self};
+
+type FnvIndexMap<K, V> = IndexMap<K, V, FnvBuildHasher>;
+
+pub fn transform_fixture(fixture: &Fixture<'_>) -> Result<String, String> {
+    let parts = fixture.content.split("%extensions%").collect::<Vec<_>>();
+    let (source, schema) = match parts.as_slice() {
+        [source, extensions] => (source, get_test_schema_with_extensions(extensions)),
+        [source] => (source, get_test_schema()),
+        _ => panic!(),
+    };
+
+    let source_location = SourceLocationKey::standalone(fixture.file_name);
+
+    let mut sources = FnvHashMap::default();
+    sources.insert(source_location, source);
+    let ast = parse_executable(source, source_location).unwrap_or_else(|e| {
+        panic!("Encountered error building AST: {:?}", e);
+    });
+    let ir = build(&schema, &ast.definitions).unwrap_or_else(|e| {
+        panic!("Encountered error building IR {:?}", e);
+    });
+    let program = Program::from_definitions(Arc::clone(&schema), ir);
+    let mut custom_scalar_types = FnvIndexMap::default();
+    custom_scalar_types.insert(
+        "JSON".intern(),
+        CustomScalarType::Path(CustomScalarTypeImport {
+            name: "JSON".intern(),
+            path: "TypeDefsFile".into(),
+        }),
+    );
+    let project_config = ProjectConfig {
+        name: "test".intern(),
+        js_module_format: JsModuleFormat::Haste,
+        typegen_config: TypegenConfig {
+            language: TypegenLanguage::TypeScript,
+            use_import_type_syntax: true,
+            custom_scalar_types,
+            ..Default::default()
+        },
+        feature_flags: Arc::new(FeatureFlags {
+            enable_fragment_aliases: FeatureFlag::Enabled,
+            ..Default::default()
+        }),
+        ..Default::default()
+    };
+    let programs = apply_transforms(
+        &project_config,
+        Arc::new(program),
+        Default::default(),
+        Arc::new(ConsoleLogger),
+        None,
+        None,
+    )
+    .unwrap();
+
+    let fragment_locations = FragmentLocations::new(programs.typegen.fragments());
+    let mut operations: Vec<_> = programs.typegen.operations().collect();
+    operations.sort_by_key(|op| op.name.item);
+    let operation_strings = operations.into_iter().map(|typegen_operation| {
+        let normalization_operation = programs
+            .normalization
+            .operation(typegen_operation.name.item)
+            .unwrap();
+        relay_typegen::generate_operation_type_exports_section(
+            typegen_operation,
+            normalization_operation,
+            &schema,
+            &project_config,
+            &fragment_locations,
+        )
+    });
+
+    let mut fragments: Vec<_> = programs.typegen.fragments().collect();
+    fragments.sort_by_key(|frag| frag.name.item);
+    let fragment_strings = fragments.into_iter().map(|frag| {
+        relay_typegen::generate_fragment_type_exports_section(
+            frag,
+            &schema,
+            &project_config,
+            &fragment_locations,
+        )
+    });
+
+    let mut result: Vec<String> = operation_strings.collect();
+    result.extend(fragment_strings);
+    Ok(result
+        .join("-------------------------------------------------------------------------------\n"))
+}

compiler/crates/relay-typegen/tests/generate_typescript_import_syntax_test.rs

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @generated SignedSource<<fbb84200234cfe7d4293dd0c63574aab>>
+ */
+
+mod generate_typescript_import_syntax;
+
+use generate_typescript_import_syntax::transform_fixture;
+use fixture_tests::test_fixture;
+
+#[test]
+fn simple() {
+    let input = include_str!("generate_typescript_import_syntax/fixtures/simple.graphql");
+    let expected = include_str!("generate_typescript_import_syntax/fixtures/simple.expected");
+    test_fixture(transform_fixture, "simple.graphql", "generate_typescript_import_syntax/fixtures/simple.expected", input, expected);
+}