Fixes Self not found in match statement.

sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs

@@ -305,6 +305,17 @@ impl ty::TyImplTrait {
             .with_help_text("")
             .with_type_annotation(type_engine.insert(decl_engine, TypeInfo::Unknown));
 
+        // Insert implementing type decl as `Self` symbol.
+        let self_decl: Option<ty::TyDecl> = match type_engine.get(implementing_for.type_id) {
+            TypeInfo::Enum(r) => Some(r.into()),
+            TypeInfo::Struct(r) => Some(r.into()),
+            _ => None,
+        };
+        if let Some(self_decl) = self_decl {
+            ctx.namespace
+                .insert_symbol(Ident::new_no_span("Self".to_string()), self_decl);
+        }
+
         // type check the items inside of the impl block
         let mut new_items = vec![];
 

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

@@ -18,11 +18,22 @@ impl Eq for Initialized {
     }
 }
 
+impl Initialized {
+    fn foo(self) -> bool {
+        match self {
+            Self::True(_) => true,
+            Self::False(_) => false,
+        }
+    }
+}
+
 fn main() -> u64 {
     let a = Initialized::True;
     let b = Initialized::False;
     let c = a == b;
     assert(c == false);
 
+    assert(a.foo());
+
     1
 }