feat: Print a hint/warning towards necessary feature gates when impor…

…ting modules
gluon-lang · Sep 2, 2018 · 9b96e51 · 9b96e51
1 parent e1f7ddf
commit 9b96e51
Show file tree

Hide file tree

Showing 2 changed files with 39 additions and 18 deletions.
diff --git a/src/import.rs b/src/import.rs
@@ -406,6 +406,28 @@ pub fn add_extern_module(thread: &Thread, name: &str, loader: ExternLoader) {
     import.add_loader(name, loader);
 }
 
+macro_rules! add_extern_module_if {
+    (
+        #[cfg($($features: tt)*)], 
+        available_if = $msg: expr,
+        args($vm: expr, $mod_name: expr, $loader: path)
+    ) => {{
+        #[cfg($($features)*)]
+        $crate::import::add_extern_module($vm, $mod_name, $loader);
+
+        #[cfg(not($($features)*))]
+        $crate::import::add_extern_module($vm, $mod_name, |_: &::vm::thread::Thread| -> ::vm::Result<::vm::ExternModule> {
+            Err(::vm::Error::Message(
+                format!(
+                    "{} is only available if {}",
+                    $mod_name,
+                    $msg
+                )
+            ))
+        });
+    }};
+}
+
 fn get_state<'m>(macros: &'m mut MacroExpander) -> &'m mut State {
     macros
         .state

diff --git a/src/lib.rs b/src/lib.rs
@@ -33,6 +33,7 @@ pub extern crate gluon_parser as parser;
 pub extern crate gluon_vm as vm;
 
 pub mod compiler_pipeline;
+#[macro_use]
 pub mod import;
 pub mod io;
 #[cfg(all(feature = "rand", not(target_arch = "wasm32")))]
@@ -692,11 +693,23 @@ impl VmBuilder {
         add_extern_module(&vm, "std.debug.prim", ::vm::debug::load);
         add_extern_module(&vm, "std.io.prim", ::io::load);
 
-        #[cfg(feature = "serialization")]
-        add_extern_module(&vm, "std.json.prim", ::vm::api::json::load);
+        add_extern_module_if!(
+            #[cfg(feature = "serialization")],
+            available_if = "gluon is compiled with the 'serialization' feature",
+            args(&vm, "std.json.prim", ::vm::api::json::load)
+        );
+
+        add_extern_module_if!(
+            #[cfg(feature = "regex")], 
+            available_if = "gluon is compiled with the 'regex' feature",
+            args(&vm, "std.regex", ::regex_bind::load)
+        );
 
-        load_regex(&vm);
-        load_random(&vm);
+        add_extern_module_if!(
+            #[cfg(all(feature = "rand", not(target_arch = "wasm32")))],
+            available_if = "gluon is compiled with the 'rand' feature and is not targeting WASM",
+            args(&vm, "std.random.prim", ::rand_bind::load)
+        );
 
         vm
     }
@@ -708,20 +721,6 @@ pub fn new_vm() -> RootedThread {
     VmBuilder::default().build()
 }
 
-#[cfg(feature = "regex")]
-fn load_regex(vm: &Thread) {
-    add_extern_module(&vm, "std.regex", ::regex_bind::load);
-}
-#[cfg(not(feature = "regex"))]
-fn load_regex(_: &Thread) {}
-
-#[cfg(all(feature = "rand", not(target_arch = "wasm32")))]
-fn load_random(vm: &Thread) {
-    add_extern_module(&vm, "std.random.prim", ::rand_bind::load);
-}
-#[cfg(any(not(feature = "rand"), target_arch = "wasm32"))]
-fn load_random(_: &Thread) {}
-
 #[cfg(test)]
 mod tests {
     use super::*;