Merge pull request #5363 from roc-lang/i5344

Correctly include flex vars in generalization group of rec defs

crates/compiler/constrain/src/expr.rs

@@ -3594,7 +3594,7 @@ fn constraint_recursive_function(
             let expr_con = attach_resolution_constraints(constraints, env, expr_con);
             let def_con = expr_con;
 
-            flex_info.vars = vec![expr_var];
+            flex_info.vars.push(expr_var);
             flex_info.constraints.push(def_con);
             flex_info.def_types.insert(
                 loc_symbol.value,

crates/compiler/test_solve_helpers/src/lib.rs

@@ -258,6 +258,7 @@ pub struct InferOptions {
     pub print_can_decls: bool,
     pub print_only_under_alias: bool,
     pub print_ranks: bool,
+    pub print_variables: bool,
     pub no_promote: bool,
 }
 
@@ -467,6 +468,7 @@ impl<'a> QueryCtx<'a> {
                 print_lambda_sets: true,
                 print_only_under_alias: self.options.print_only_under_alias,
                 print_ranks: self.options.print_ranks,
+                print_variables: self.options.print_variables,
                 ignore_polarity: true,
                 print_weakened_vars: true,
             },

crates/compiler/types/src/pretty_print.rs

@@ -62,6 +62,7 @@ pub struct DebugPrint {
     pub print_ranks: bool,
     pub ignore_polarity: bool,
     pub print_weakened_vars: bool,
+    pub print_variables: bool,
 }
 
 impl DebugPrint {
@@ -71,6 +72,7 @@ impl DebugPrint {
         print_ranks: false,
         ignore_polarity: false,
         print_weakened_vars: false,
+        print_variables: false,
     };
 }
 
@@ -658,6 +660,12 @@ fn write_content<'a>(
     if env.debug.print_ranks {
         buf.push_str(&format!("⟨@{:?}⟩", subs.get_rank(var).into_usize()));
     }
+    if env.debug.print_variables {
+        buf.push_str(&format!(
+            "<{:?}>",
+            subs.get_root_key_without_compacting(var)
+        ));
+    }
 
     match subs.get_content_without_compacting(var) {
         FlexVar(Some(name_index)) => {

crates/compiler/uitest/src/uitest.rs

@@ -257,6 +257,7 @@ impl<'a> TestCase<'a> {
                 "allow_errors" => infer_opts.allow_errors = true,
                 "print_only_under_alias" => infer_opts.print_only_under_alias = true,
                 "print_ranks" => infer_opts.print_ranks = true,
+                "print_variables" => infer_opts.print_variables = true,
                 other => return Err(format!("unknown infer option: {other:?}").into()),
             }
         }

crates/compiler/uitest/tests/recursion/generalization_among_large_recursive_group.txt

@@ -0,0 +1,24 @@
+# +opt infer:print_variables
+
+app "test" provides [main] to "./platform"
+
+f = \{} ->
+#^{-1} <1527><116>{} -<119>[[f(1)]]-> <115>[Ok <1535>{}]<79>*
+    when g {} is
+#        ^ <1517><1535>{} -<1525>[[g(2)]]-> <71>[Ok <1535>{}]<101>*
+        _ -> Ok {}
+
+g = \{} ->
+#^{-1} <1517><1535>{} -<1525>[[g(2)]]-> <71>[Ok <1535>{}]<101>*
+    when h {} is
+#        ^ <1522><1535>{} -<1530>[[h(3)]]-> <93>[Ok <1535>{}]<123>*
+        _ -> Ok {}
+
+h = \{} ->
+#^{-1} <1522><1535>{} -<1530>[[h(3)]]-> <93>[Ok <1535>{}]<123>*
+    when f {} is
+#        ^ <1527><116>{} -<119>[[f(1)]]-> <115>[Ok <1535>{}]<79>*
+        _ -> Ok {}
+
+main = f {}
+#      ^ <1537><132>{} -<135>[[f(1)]]-> <137>[Ok <1535>{}]<1536>w_a