Adds reuse of enum variant TypeId.

We already do unification of expressions with type annotation when necessary,
but these were not affecting enum variants because we used separate TypeIds for
the expression and for the enum variant.

With this change the enum variant and the expressions will share the same TypeId,
making unification to the expression to also affect the enum variant.

Fixes #5492
Fixes #5581

Probably helpful for #5559

sway-core/src/semantic_analysis/ast_node/expression/typed_expression/enum_instantiation.rs

@@ -90,7 +90,8 @@ pub(crate) fn instantiate_enum(
                 .with_help_text("Enum instantiator must match its declared variant type.")
                 .with_type_annotation(start_type);
 
-            let typed_expr = ty::TyExpression::type_check(handler, enum_ctx, single_expr.clone())?;
+            let mut typed_expr =
+                ty::TyExpression::type_check(handler, enum_ctx, single_expr.clone())?;
 
             // unify the value of the argument with the variant
             handler.scope(|handler| {
@@ -106,6 +107,9 @@ pub(crate) fn instantiate_enum(
                 Ok(())
             })?;
 
+            // Reuse the TypeId so further unification in typed_expr.return_type also affect enum_variant.type_argument.type_id
+            typed_expr.return_type = enum_variant.type_argument.type_id;
+
             // we now know that the instantiator type matches the declared type, via the above tpe
             // check
 

test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.lock

@@ -0,0 +1,16 @@
+[[package]]
+name = "core"
+source = "path+from-root-F6BA7257B3F9949F"
+
+[[package]]
+name = "enum_variant_unification"
+source = "member"
+dependencies = [
+    "core",
+    "std",
+]
+
+[[package]]
+name = "std"
+source = "path+from-root-F6BA7257B3F9949F"
+dependencies = ["core"]

test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.toml

@@ -0,0 +1,9 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "enum_variant_unification"
+
+[dependencies]
+core = { path = "../../../../../../../sway-lib-core" }
+std = { path = "../../../../../../../sway-lib-std" }

test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/src/main.sw

@@ -0,0 +1,33 @@
+script;
+
+struct S<T> {
+    x: T,
+}
+
+fn main() -> u64 {
+  // https://github.com/FuelLabs/sway/issues/5492
+  let _ = foo();
+  let _ = bar(true);
+
+  // https://github.com/FuelLabs/sway/issues/5581
+  let _: S<Option<u8>>  = S { x: Option::Some(1) };
+
+  0
+}
+
+#[inline(never)]
+fn foo() -> Option<u8> {
+  match Some(true) {
+    Option::Some(_b) => Option::Some(17),
+    Option::None => Option::None,
+  }
+}
+
+#[inline(never)]
+fn bar(b: bool) -> Option<u8> {
+   if(b) {
+     Option::Some(19)
+   } else {
+     Option::None
+   }
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/test.toml

@@ -0,0 +1,4 @@
+category = "run"
+expected_result = { action = "return", value = 0 }
+validate_abi = false
+expected_warnings = 3