8 files changed, 67 insertions, 2 deletions
diff --git a/cli/ast.rs b/cli/ast.rs
index a8bc5adb4..e22b242d7 100644
--- a/cli/ast.rs
+++ b/cli/ast.rs
@@ -182,6 +182,13 @@ pub fn get_syntax(media_type: &MediaType) -> Syntax {
   }
 }
 
+#[derive(Debug, Clone)]
+pub enum ImportsNotUsedAsValues {
+  Remove,
+  Preserve,
+  Error,
+}
+
 /// Options which can be adjusted when transpiling a module.
 #[derive(Debug, Clone)]
 pub struct EmitOptions {
@@ -191,6 +198,10 @@ pub struct EmitOptions {
   /// When emitting a legacy decorator, also emit experimental decorator meta
   /// data.  Defaults to `false`.
   pub emit_metadata: bool,
+  /// What to do with import statements that only import types i.e. whether to
+  /// remove them (`Remove`), keep them as side-effect imports (`Preserve`)
+  /// or error (`Error`). Defaults to `Remove`.
+  pub imports_not_used_as_values: ImportsNotUsedAsValues,
   /// Should the source map be inlined in the emitted code file, or provided
   /// as a separate file.  Defaults to `true`.
   pub inline_source_map: bool,
@@ -209,6 +220,7 @@ impl Default for EmitOptions {
     EmitOptions {
       check_js: false,
       emit_metadata: false,
+      imports_not_used_as_values: ImportsNotUsedAsValues::Remove,
       inline_source_map: true,
       jsx_factory: "React.createElement".into(),
       jsx_fragment_factory: "React.Fragment".into(),
@@ -221,9 +233,16 @@ impl From<tsc_config::TsConfig> for EmitOptions {
   fn from(config: tsc_config::TsConfig) -> Self {
     let options: tsc_config::EmitConfigOptions =
       serde_json::from_value(config.0).unwrap();
+    let imports_not_used_as_values =
+      match options.imports_not_used_as_values.as_str() {
+        "preserve" => ImportsNotUsedAsValues::Preserve,
+        "error" => ImportsNotUsedAsValues::Error,
+        _ => ImportsNotUsedAsValues::Remove,
+      };
     EmitOptions {
       check_js: options.check_js,
       emit_metadata: options.emit_decorator_metadata,
+      imports_not_used_as_values,
       inline_source_map: options.inline_source_map,
       jsx_factory: options.jsx_factory,
       jsx_fragment_factory: options.jsx_fragment_factory,
@@ -232,6 +251,25 @@ impl From<tsc_config::TsConfig> for EmitOptions {
   }
 }
 
+fn strip_config_from_emit_options(
+  options: &EmitOptions,
+) -> typescript::strip::Config {
+  let mut config = typescript::strip::Config::default();
+  config.import_not_used_as_values = match options.imports_not_used_as_values {
+    ImportsNotUsedAsValues::Remove => {
+      typescript::strip::ImportNotUsedAsValues::Remove
+    }
+    ImportsNotUsedAsValues::Preserve => {
+      typescript::strip::ImportNotUsedAsValues::Preserve
+    }
+    // `Error` only affects the type-checking stage. Fall back to `Remove` here.
+    ImportsNotUsedAsValues::Error => {
+      typescript::strip::ImportNotUsedAsValues::Remove
+    }
+  };
+  config
+}
+
 /// A logical structure to hold the value of a parsed module for further
 /// processing.
 #[derive(Clone)]
@@ -299,7 +337,9 @@ impl ParsedModule {
         emit_metadata: options.emit_metadata
       }),
       helpers::inject_helpers(),
-      typescript::strip(),
+      typescript::strip::strip_with_config(strip_config_from_emit_options(
+        options
+      )),
       fixer(Some(&self.comments)),
       hygiene(),
     );
@@ -513,7 +553,9 @@ pub fn transpile_module(
       emit_metadata: emit_options.emit_metadata
     }),
     helpers::inject_helpers(),
-    typescript::strip(),
+    typescript::strip::strip_with_config(strip_config_from_emit_options(
+      emit_options
+    )),
     fixer(Some(&parsed_module.comments)),
   );
 
diff --git a/cli/module_graph.rs b/cli/module_graph.rs
index 8a3c140ba..ad6d01589 100644
--- a/cli/module_graph.rs
+++ b/cli/module_graph.rs
@@ -773,6 +773,7 @@ impl Graph {
     let mut ts_config = TsConfig::new(json!({
       "checkJs": false,
       "emitDecoratorMetadata": false,
+      "importsNotUsedAsValues": "remove",
       "inlineSourceMap": true,
       "jsx": "react",
       "jsxFactory": "React.createElement",
@@ -814,6 +815,7 @@ impl Graph {
         // TODO(@kitsonk) consider enabling this by default
         //   see: https://github.com/denoland/deno/issues/7732
         "emitDecoratorMetadata": false,
+        "importsNotUsedAsValues": "remove",
         "inlineSourceMap": true,
         "outDir": "deno://",
         "removeComments": true,
@@ -942,6 +944,7 @@ impl Graph {
       "emitDecoratorMetadata": false,
       "esModuleInterop": true,
       "experimentalDecorators": true,
+      "importsNotUsedAsValues": "remove",
       "inlineSourceMap": false,
       "isolatedModules": true,
       "jsx": "react",
@@ -1589,6 +1592,7 @@ impl Graph {
     let mut ts_config = TsConfig::new(json!({
       "checkJs": false,
       "emitDecoratorMetadata": false,
+      "importsNotUsedAsValues": "remove",
       "inlineSourceMap": true,
       "jsx": "react",
       "jsxFactory": "React.createElement",
diff --git a/cli/tests/087_hello.ts b/cli/tests/087_hello.ts
new file mode 100644
index 000000000..1a9d8f114
--- /dev/null
+++ b/cli/tests/087_hello.ts
@@ -0,0 +1,2 @@
+export type SomeType = unknown;
+console.log("Hello, world!");
diff --git a/cli/tests/087_no_check_imports_not_used_as_values.ts b/cli/tests/087_no_check_imports_not_used_as_values.ts
new file mode 100644
index 000000000..64a13f9b1
--- /dev/null
+++ b/cli/tests/087_no_check_imports_not_used_as_values.ts
@@ -0,0 +1,4 @@
+import { SomeType } from "./087_hello.ts";
+
+const string: SomeType = "Hi!";
+console.log(string);
diff --git a/cli/tests/087_no_check_imports_not_used_as_values.ts.out b/cli/tests/087_no_check_imports_not_used_as_values.ts.out
new file mode 100644
index 000000000..f744c4183
--- /dev/null
+++ b/cli/tests/087_no_check_imports_not_used_as_values.ts.out
@@ -0,0 +1,2 @@
+[WILDCARD]Hello, world!
+Hi!
diff --git a/cli/tests/integration_tests.rs b/cli/tests/integration_tests.rs
index de5cc6aae..a09b331d8 100644
--- a/cli/tests/integration_tests.rs
+++ b/cli/tests/integration_tests.rs
@@ -2837,6 +2837,11 @@ console.log("finish");
     output: "086_dynamic_import_already_rejected.ts.out",
   });
 
+  itest!(_087_no_check_imports_not_used_as_values {
+    args: "run --config preserve_imports.tsconfig.json --no-check 087_no_check_imports_not_used_as_values.ts",
+    output: "087_no_check_imports_not_used_as_values.ts.out",
+  });
+
   itest!(js_import_detect {
     args: "run --quiet --reload js_import_detect.ts",
     output: "js_import_detect.ts.out",
diff --git a/cli/tests/preserve_imports.tsconfig.json b/cli/tests/preserve_imports.tsconfig.json
new file mode 100644
index 000000000..9b19291aa
--- /dev/null
+++ b/cli/tests/preserve_imports.tsconfig.json
@@ -0,0 +1,5 @@
+{
+  "compilerOptions": {
+    "importsNotUsedAsValues": "preserve"
+  }
+}
diff --git a/cli/tsc_config.rs b/cli/tsc_config.rs
index 9d380f967..54ed34bf1 100644
--- a/cli/tsc_config.rs
+++ b/cli/tsc_config.rs
@@ -23,6 +23,7 @@ use std::str::FromStr;
 pub struct EmitConfigOptions {
   pub check_js: bool,
   pub emit_decorator_metadata: bool,
+  pub imports_not_used_as_values: String,
   pub inline_source_map: bool,
   pub jsx: String,
   pub jsx_factory: String,