fix uniq record destructure patterns

src/solve.rs

@@ -7,7 +7,6 @@ use crate::types::Constraint::{self, *};
 use crate::types::Problem;
 use crate::types::Type::{self, *};
 use crate::unify::{unify, Unified};
-use crate::uniqueness::boolean_algebra::Bool;
 
 type Env = ImMap<Symbol, Variable>;
 
@@ -402,7 +401,6 @@ fn type_to_variable(
 
             register(subs, rank, pools, content)
         }
-        // Boolean(Bool::Variable(var)) => *var,
         Boolean(b) => {
             let content = Content::Structure(FlatType::Boolean(b.clone()));
 

src/uniqueness/mod.rs

@@ -119,27 +119,23 @@ fn constrain_pattern(
             } in patterns
             {
                 let pat_type = Type::Variable(*var);
-                let pattern_expected = PExpected::NoExpectation(pat_type.clone());
+                let expected = PExpected::NoExpectation(pat_type.clone());
 
-                match guard {
-                    Some((_guard_var, loc_guard)) => {
-                        state.headers.insert(
-                            symbol.clone(),
-                            Located {
-                                region: pattern.region,
-                                value: pat_type.clone(),
-                            },
-                        );
+                if !state.headers.contains_key(&symbol) {
+                    state.headers.insert(
+                        symbol.clone(),
+                        Located::at(pattern.region, pat_type.clone()),
+                    );
+                }
 
-                        constrain_pattern(var_store, state, loc_guard, pattern_expected);
-                    }
-                    None => {
-                        constrain_pattern(var_store, state, pattern, pattern_expected);
-                    }
+                field_types.insert(label.clone(), pat_type.clone());
+
+                // TODO investigate: shouldn't guard_var be constrained somewhere?
+                if let Some((_guard_var, loc_guard)) = guard {
+                    constrain_pattern(var_store, state, loc_guard, expected);
                 }
 
                 state.vars.push(*var);
-                field_types.insert(label.clone(), pat_type);
             }
 
             let record_type =
@@ -275,7 +271,9 @@ pub fn constrain_expr(
             symbol_for_lookup, ..
         } => {
             var_usage.register(symbol_for_lookup);
-            match var_usage.get_usage(symbol_for_lookup) {
+            let usage = var_usage.get_usage(symbol_for_lookup);
+
+            match usage {
                 Some(sharing::ReferenceCount::Shared) => {
                     // the variable is used/consumed more than once, so it must be Shared
                     let val_var = var_store.fresh();

tests/helpers/mod.rs

@@ -122,6 +122,7 @@ pub fn uniq_expr_with(
 
     let next_var = var_store1.into();
     let subs1 = Subs::new(next_var);
+
     // double check
     let var_store2 = VarStore::new(next_var);
 

tests/test_infer.rs

@@ -1068,6 +1068,24 @@ mod test_infer {
         );
     }
 
+    #[test]
+    fn record_extraction() {
+        with_larger_debug_stack(|| {
+            infer_eq(
+                indoc!(
+                    r#"
+                f = \x -> 
+                    when x is 
+                        { a, b } -> a
+
+                f
+                "#
+                ),
+                "{ a : a, b : * }* -> a",
+            );
+        });
+    }
+
     // currently doesn't work because of a parsing issue
     // @Foo x y isn't turned into Apply(@Foo, [x,y]) currently
     // #[test]

tests/test_uniqueness_infer.rs

@@ -10,7 +10,7 @@ mod helpers;
 
 #[cfg(test)]
 mod test_infer_uniq {
-    use crate::helpers::uniq_expr;
+    use crate::helpers::{uniq_expr, with_larger_debug_stack};
     use roc::infer::infer_expr;
     use roc::pretty_print_types::{content_to_string, name_all_type_vars};
 
@@ -920,4 +920,22 @@ mod test_infer_uniq {
             "Attr.Attr * { year : (Attr.Attr * Str) }{ name : (Attr.Attr * Str) }",
         );
     }
+
+    //    #[test]
+    //    fn record_extraction() {
+    //        with_larger_debug_stack(|| {
+    //            infer_eq(
+    //                indoc!(
+    //                    r#"
+    //                f = \x ->
+    //                    when x is
+    //                        { a, b } -> a
+    //
+    //                f
+    //                "#
+    //                ),
+    //                "Attr.Attr * (Attr.Attr u { a : Attr u a, b : * }* -> Attr u a)",
+    //            );
+    //        });
+    //    }
 }