skeleton for unsized glue

crates/glue/src/RustGlue.roc

@@ -1,7 +1,10 @@
 app "rust-glue"
     packages { pf: "../platform/main.roc" }
     imports [
-        pf.Types.{ Types }, pf.Shape.{ Shape, RocFn }, pf.File.{ File }, pf.TypeId.{ TypeId },
+        pf.Types.{ Types },
+        pf.Shape.{ Shape, RocFn },
+        pf.File.{ File },
+        pf.TypeId.{ TypeId },
         "../static/Cargo.toml" as rocAppCargoToml : Str,
         "../../roc_std/Cargo.toml" as rocStdCargoToml : Str,
         "../../roc_std/src/lib.rs" as rocStdLib : Str,
@@ -39,8 +42,7 @@ makeGlue = \typesByArch ->
 
 ## These are always included, and don't depend on the specifics of the app.
 staticFiles : List File
-staticFiles =
+staticFiles = [
-    [
     { name: "roc_app/Cargo.toml", content: rocAppCargoToml },
     { name: "roc_std/Cargo.toml", content: rocStdCargoToml },
     { name: "roc_std/src/lib.rs", content: rocStdLib },
@@ -845,6 +847,32 @@ generateRecursiveTagUnion = \buf, types, id, tagUnionName, tags, discriminantSiz
                 None ->
                     []
 
+        fieldGetters =
+            List.walk payloadFields { i: 0, accum: "" } \{ i, accum }, fieldTypeId ->
+                fieldTypeName = typeName types fieldTypeId
+                fieldIndex = Num.toStr i
+
+                {
+                    i: i + 1,
+                    accum:
+                    """
+                    \(accum)
+                        pub fn get_\(tagName)_f\(fieldIndex)(&self) -> &\(fieldTypeName) {
+                            debug_assert!(self.is_\(tagName)());
+
+                            // extern "C" {
+                            //     fn foobar(tag_id: u16, field_index: usize) -> usize;
+                            // }
+
+                            // let offset = unsafe { foobar(\(fieldIndex)) };
+                            let offset = 0;
+                            unsafe { &*self.unmasked_pointer().add(offset).cast() }
+                        }
+
+                    """,
+                }
+            |> .accum
+
         payloadFieldNames =
             commaSeparated "" payloadFields \_, i ->
                 n = Num.toStr i
@@ -896,6 +924,7 @@ generateRecursiveTagUnion = \buf, types, id, tagUnionName, tags, discriminantSiz
 
                     Self((ptr as usize | tag_id as usize) as *mut _)
                 }
+            \(fieldGetters)
 
                 pub fn get_\(tagName)(mut self) -> \(escapedName)_\(tagName) {
                     debug_assert!(self.is_\(tagName)());
@@ -1040,8 +1069,6 @@ generateRecursiveTagUnion = \buf, types, id, tagUnionName, tags, discriminantSiz
         |> List.mapWithIndex hashCase
         |> Str.joinWith "\n"
 
-
-
     hashImpl =
         if canSupportPartialEqOrd types (Types.shape types id) then
             """
@@ -1144,7 +1171,7 @@ generateRecursiveTagUnion = \buf, types, id, tagUnionName, tags, discriminantSiz
                 }
             }
 
-            unsafe fn ptr_read_union(&self) -> core::mem::ManuallyDrop<union_\(escapedName)> {
+            fn unmasked_pointer(&self) -> *mut union_Op {
                 debug_assert!(!self.0.is_null());
 
                 let mask = match std::mem::size_of::<usize>() {
@@ -1153,7 +1180,11 @@ generateRecursiveTagUnion = \buf, types, id, tagUnionName, tags, discriminantSiz
                     _ => unreachable!(),
                 };
 
-                let ptr = ((self.0 as usize) & mask) as *mut union_\(escapedName);
+                ((self.0 as usize) & mask) as *mut union_Op
+            }
+
+            unsafe fn ptr_read_union(&self) -> core::mem::ManuallyDrop<union_Op> {
+                let ptr = self.unmasked_pointer();
 
                 core::mem::ManuallyDrop::new(unsafe { std::ptr::read(ptr) })
             }
@@ -1808,7 +1839,6 @@ cannotSupportDefault = \types, type ->
             cannotSupportDefault types (Types.shape types id)
 
         TagUnionPayload { fields: HasClosure _ } -> Bool.true
-
         RocDict keyId valId ->
             cannotSupportCopy types (Types.shape types keyId)
             || cannotSupportCopy types (Types.shape types valId)
@@ -2090,7 +2120,6 @@ nextMultipleOf = \lhs, rhs ->
         0 -> lhs
         r -> lhs + (rhs - r)
 
-
 isUnit : Shape -> Bool
 isUnit = \shape ->
     when shape is

examples/glue/rust-platform/Cargo.toml

@@ -16,7 +16,8 @@ name = "host"
 path = "src/main.rs"
 
 [dependencies]
-roc_std = { path = "../../../crates/roc_std" }
+roc_app = { path = "roc_app" }
+roc_std = { path = "roc_std" }
 libc = "0.2"
 
 [workspace]

examples/glue/rust-platform/src/lib.rs

@@ -1,15 +1,13 @@
 #![allow(non_snake_case)]
 
-mod test_glue;
-
 use core::ffi::c_void;
+use roc_app::Op;
 use roc_std::RocStr;
 use std::ffi::CStr;
 use std::io::Write;
 use std::os::raw::c_char;
-use test_glue::Op;
 
-use test_glue::mainForHost as roc_main;
+use roc_app::mainForHost as roc_main;
 
 #[no_mangle]
 pub unsafe extern "C" fn roc_alloc(size: usize, _alignment: u32) -> *mut c_void {
@@ -80,7 +78,7 @@ pub unsafe extern "C" fn roc_shm_open(
 
 #[no_mangle]
 pub extern "C" fn rust_main() -> i32 {
-    use test_glue::discriminant_Op::*;
+    use roc_app::discriminant_Op::*;
 
     println!("Let's do things!");
 
@@ -91,7 +89,7 @@ pub extern "C" fn rust_main() -> i32 {
             StdoutWrite => {
                 let stdout_write = op.get_StdoutWrite();
                 let output: RocStr = stdout_write.f0;
-                op = unsafe { stdout_write.f1.force_thunk(()) };
+                op = unsafe { stdout_write.f1.force_thunk() };
 
                 if let Err(e) = std::io::stdout().write_all(output.as_bytes()) {
                     panic!("Writing to stdout failed! {:?}", e);
@@ -100,7 +98,7 @@ pub extern "C" fn rust_main() -> i32 {
             StderrWrite => {
                 let stderr_write = op.get_StderrWrite();
                 let output: RocStr = stderr_write.f0;
-                op = unsafe { stderr_write.f1.force_thunk(()) };
+                op = unsafe { stderr_write.f1.force_thunk() };
 
                 if let Err(e) = std::io::stderr().write_all(output.as_bytes()) {
                     panic!("Writing to stdout failed! {:?}", e);