Add electron support via --omit-imports (#1958)

Author: silvanshade

crates/cli-support/src/js/mod.rs

@@ -316,6 +316,11 @@ impl<'a> Context<'a> {
 
     fn js_import_header(&self) -> Result<String, Error> {
         let mut imports = String::new();
+
+        if self.config.omit_imports {
+            return Ok(imports)
+        }
+
         match &self.config.mode {
             OutputMode::NoModules { .. } => {
                 for (module, _items) in self.js_imports.iter() {

crates/cli-support/src/lib.rs

@@ -26,6 +26,7 @@ pub struct Bindgen {
     mode: OutputMode,
     debug: bool,
     typescript: bool,
+    omit_imports: bool,
     demangle: bool,
     keep_debug: bool,
     remove_name_section: bool,
@@ -97,6 +98,7 @@ impl Bindgen {
             },
             debug: false,
             typescript: false,
+            omit_imports: false,
             demangle: true,
             keep_debug: false,
             remove_name_section: false,
@@ -222,6 +224,11 @@ impl Bindgen {
         self
     }
 
+    pub fn omit_imports(&mut self, omit_imports: bool) -> &mut Bindgen {
+        self.omit_imports = omit_imports;
+        self
+    }
+
     pub fn demangle(&mut self, demangle: bool) -> &mut Bindgen {
         self.demangle = demangle;
         self

crates/cli/src/bin/wasm-bindgen.rs

@@ -28,6 +28,7 @@ Options:
     --browser                    Hint that JS should only be compatible with a browser
     --typescript                 Output a TypeScript definition file (on by default)
     --no-typescript              Don't emit a *.d.ts file
+    --omit-imports               Don't emit imports in generated JavaScript
     --debug                      Include otherwise-extraneous debug checks in output
     --no-demangle                Don't demangle Rust symbol names
     --keep-debug                 Keep debug sections in wasm files
@@ -49,6 +50,7 @@ struct Args {
     flag_no_modules: bool,
     flag_typescript: bool,
     flag_no_typescript: bool,
+    flag_omit_imports: bool,
     flag_out_dir: Option<PathBuf>,
     flag_out_name: Option<String>,
     flag_debug: bool,
@@ -109,7 +111,8 @@ fn rmain(args: &Args) -> Result<(), Error> {
         .keep_debug(args.flag_keep_debug)
         .remove_name_section(args.flag_remove_name_section)
         .remove_producers_section(args.flag_remove_producers_section)
-        .typescript(typescript);
+        .typescript(typescript)
+        .omit_imports(args.flag_omit_imports);
     if let Some(ref name) = args.flag_no_modules_global {
         b.no_modules_global(name)?;
     }

guide/src/reference/cli.md

@@ -48,6 +48,15 @@ is on by default.
 By default, a `*.d.ts` TypeScript declaration file is generated for the
 generated JavaScript bindings, but this flag will disable that.
 
+### `--omit-imports`
+
+When the `module` attribute is used with the `wasm-bindgen` macro, the code
+generator will emit corresponding `import` or `require` statements in the header
+section of the generated javascript. This flag causes those import statements to
+be omitted. This is necessary for some use cases, such as generating javascript
+which is intended to be used with Electron (with node integration disabled),
+where the imports are instead handled through a separate preload script.
+
 ### `--debug`
 
 Generates a bit more JS and wasm in "debug mode" to help catch programmer