Fix bug in custom binops where their return types aren't inferred

examples/imported_type.reid

@@ -1,19 +1,9 @@
 
 import std::print;
 import std::from_str;
-import std::concat_strings;
-import std::free_string;
 import std::String;
 
-fn otus(param: &mut String) {
-    let b: String = from_str(" bello");
-    concat_strings(param, b);
-    free_string(&b);
-}
-
 fn main() -> u8 {
-    let mut otus = from_str("hello");
-    otus(&mut otus);
-    print(otus + " beep");
+    print((from_str("hello") + " beep: ") + 1234u64);
     return 0;
 }

examples/testmod.reid

@@ -0,0 +1,10 @@
+
+struct Otus {}
+
+impl binop (lhs: Otus) + (rhs: u64) -> Otus {
+    return lhs;
+}
+
+pub fn make_otus() -> Otus {
+    return Otus {};
+}

reid/lib/std.reid

@@ -16,7 +16,13 @@ impl binop (lhs: String) + (rhs: *char) -> String {
     let added = from_str(rhs);
     concat_strings(&mut new, added);
     free_string(&added);
-    return lhs;
+    return new;
+}
+
+impl binop (lhs: String) + (rhs: u64) -> String {
+    let mut new = lhs;
+    add_num_to_str(&mut new, rhs);
+    return new;
 }
 
 struct div_t {

reid/src/lib.rs

@@ -173,9 +173,9 @@ pub fn perform_all_passes<'map>(
         ));
     }
 
-    let refs = TypeRefs::with_binops(binops);
+    let mut refs = TypeRefs::with_binops(binops);
 
-    let state = context.pass(&mut TypeInference { refs: &refs })?;
+    let state = context.pass(&mut TypeInference { refs: &mut refs })?;
 
     #[cfg(debug_assertions)]
     println!("{:-^100}", "TYPE INFERRER OUTPUT");

reid/src/mir/typecheck/typeinference.rs

@@ -33,7 +33,7 @@ use super::{
 /// TypeRefs-struct is used as a helper to go through the modules and change
 /// types while inferring.
 pub struct TypeInference<'t> {
-    pub refs: &'t TypeRefs,
+    pub refs: &'t mut TypeRefs,
 }
 
 impl<'t> Pass for TypeInference<'t> {
@@ -77,7 +77,18 @@ impl<'t> Pass for TypeInference<'t> {
                     binop.signature(),
                 );
             } else {
-                seen_binops.insert(binop_key);
+                seen_binops.insert(binop_key.clone());
+                self.refs
+                    .binop_types
+                    .set(
+                        binop_key,
+                        crate::mir::pass::ScopeBinopDef {
+                            hands: (binop.lhs.1.clone(), binop.rhs.1.clone()),
+                            operator: binop.op,
+                            return_ty: binop.return_type.clone(),
+                        },
+                    )
+                    .ok();
             }
         }
 
@@ -119,7 +130,6 @@ impl BinopDefinition {
             .fn_kind
             .infer_types(state, &scope_hints, Some(self.return_type.clone()))?;
         if let Some(mut ret_ty) = ret_ty {
-            dbg!(&ret_ty, &self.return_type);
             ret_ty.narrow(&scope_hints.from_type(&self.return_type).unwrap());
         }
 
@@ -320,7 +330,7 @@ impl Expression {
                             continue;
                         }
                         if binop.operator.is_commutative() {
-                            if let Some(_) = binop.narrow(&lhs_ty, &rhs_ty) {
+                            if let Some(_) = binop.narrow(&rhs_ty, &lhs_ty) {
                                 applying_binops.push(binop.clone());
                                 continue;
                             }
@@ -330,7 +340,6 @@ impl Expression {
                 } else {
                     Vec::new()
                 };
-
                 if binops.len() > 0 {
                     let binop = unsafe { binops.get_unchecked(0) };
                     let mut widened_lhs = binop.hands.0.clone();

reid/src/mir/typecheck/typerefs.rs

@@ -80,7 +80,7 @@ impl TypeRefKind {
                     while let Some(other) = binops.next() {
                         ty = ty.widen_into(&other);
                     }
-                    ty
+                    ty.clone()
                 } else {
                     TypeKind::Vague(VagueType::Unknown)
                 }