Favour public type aliases over internal types

GearsDatapacks · lpil · commit d52d08457a6a · 2025-09-11T19:32:38.000+01:00
diff --git a/compiler-core/src/exhaustiveness/printer.rs b/compiler-core/src/exhaustiveness/printer.rs
@@ -54,10 +54,10 @@ impl<'a> Printer<'a> {
                 ..
             } => {
                 let (module, name) = match self.names.named_constructor(module, name) {
-                    NameContextInformation::Qualified(m, n) => (Some(m), n),
-                    NameContextInformation::Unqualified(n) => (None, n),
-                    NameContextInformation::Unimported(n) => {
-                        (Some(module.split('/').next_back().unwrap_or(module)), n)
+                    NameContextInformation::Qualified(module, name) => (Some(module), name),
+                    NameContextInformation::Unqualified(name) => (None, name),
+                    NameContextInformation::Unimported(module, name) => {
+                        (module.split('/').next_back(), name)
                     }
                 };
 
diff --git a/compiler-core/src/language_server/code_action.rs b/compiler-core/src/language_server/code_action.rs
@@ -5014,7 +5014,7 @@ fn pretty_constructor_name(
         .names
         .named_constructor(constructor_module, constructor_name)
     {
-        type_::printer::NameContextInformation::Unimported(_) => None,
+        type_::printer::NameContextInformation::Unimported(_, _) => None,
         type_::printer::NameContextInformation::Unqualified(constructor_name) => {
             Some(eco_format!("{constructor_name}"))
         }
diff --git a/compiler-core/src/language_server/tests/action.rs b/compiler-core/src/language_server/tests/action.rs
@@ -9796,3 +9796,101 @@ fn remove_unreachable_branches_does_not_pop_up_if_all_branches_are_reachable() {
         find_position_of("Ok(n)").to_selection()
     );
 }
+
+#[test]
+fn add_type_annotations_public_alias_to_internal_type_aliased_module() {
+    let src = "
+import package as pkg
+
+pub fn main() {
+  pkg.make_wibble()
+}
+";
+
+    assert_code_action!(
+        ADD_ANNOTATION,
+        TestProject::for_source(src)
+            .add_package_module(
+                "package",
+                "package",
+                "
+import package/internal
+
+pub type Wibble = internal.Wibble
+
+pub fn make_wibble() {
+  internal.Wibble
+}
+"
+            )
+            .add_package_module("package", "package/internal", "pub type Wibble { Wibble }"),
+        find_position_of("main").to_selection(),
+    );
+}
+
+// https://github.com/gleam-lang/gleam/issues/3898
+#[test]
+fn add_type_annotations_public_alias_to_internal_type() {
+    let src = "
+import package
+
+pub fn main() {
+  package.make_wibble()
+}
+";
+
+    assert_code_action!(
+        ADD_ANNOTATION,
+        TestProject::for_source(src)
+            .add_package_module(
+                "package",
+                "package",
+                "
+import package/internal
+
+pub type Wibble = internal.Wibble
+
+pub fn make_wibble() {
+  internal.Wibble
+}
+"
+            )
+            .add_package_module("package", "package/internal", "pub type Wibble { Wibble }"),
+        find_position_of("main").to_selection(),
+    );
+}
+
+#[test]
+fn add_type_annotations_public_alias_to_internal_generic_type() {
+    let src = "
+import package
+
+pub fn main() {
+  package.make_wibble(10)
+}
+";
+
+    assert_code_action!(
+        ADD_ANNOTATION,
+        TestProject::for_source(src)
+            .add_package_module(
+                "package",
+                "package",
+                "
+import package/internal
+
+pub type Wibble(a, b) = internal.Wibble(a, b)
+
+pub fn make_wibble(x) {
+  internal.Wibble(x)
+}
+"
+            )
+            .add_package_module(
+                "package",
+                "package/internal",
+                "pub type Wibble(a, b) { Wibble(a) }"
+            ),
+        find_position_of("main").to_selection(),
+    );
+}
diff --git a/compiler-core/src/language_server/tests/snapshots/gleam_core__language_server__tests__action__add_type_annotations_public_alias_to_internal_generic_type.snap b/compiler-core/src/language_server/tests/snapshots/gleam_core__language_server__tests__action__add_type_annotations_public_alias_to_internal_generic_type.snap
@@ -0,0 +1,21 @@
+---
+source: compiler-core/src/language_server/tests/action.rs
+expression: "\nimport package\n\npub fn main() {\n  package.make_wibble(10)\n}\n"
+---
+----- BEFORE ACTION
+
+import package
+
+pub fn main() {
+       ↑       
+  package.make_wibble(10)
+}
+
+
+----- AFTER ACTION
+
+import package
+
+pub fn main() -> package.Wibble(Int, a) {
+  package.make_wibble(10)
+}
diff --git a/compiler-core/src/language_server/tests/snapshots/gleam_core__language_server__tests__action__add_type_annotations_public_alias_to_internal_type.snap b/compiler-core/src/language_server/tests/snapshots/gleam_core__language_server__tests__action__add_type_annotations_public_alias_to_internal_type.snap
@@ -0,0 +1,21 @@
+---
+source: compiler-core/src/language_server/tests/action.rs
+expression: "\nimport package\n\npub fn main() {\n  package.make_wibble()\n}\n"
+---
+----- BEFORE ACTION
+
+import package
+
+pub fn main() {
+       ↑       
+  package.make_wibble()
+}
+
+
+----- AFTER ACTION
+
+import package
+
+pub fn main() -> package.Wibble {
+  package.make_wibble()
+}
diff --git a/compiler-core/src/language_server/tests/snapshots/gleam_core__language_server__tests__action__add_type_annotations_public_alias_to_internal_type_aliased_module.snap b/compiler-core/src/language_server/tests/snapshots/gleam_core__language_server__tests__action__add_type_annotations_public_alias_to_internal_type_aliased_module.snap
@@ -0,0 +1,21 @@
+---
+source: compiler-core/src/language_server/tests/action.rs
+expression: "\nimport package as pkg\n\npub fn main() {\n  pkg.make_wibble()\n}\n"
+---
+----- BEFORE ACTION
+
+import package as pkg
+
+pub fn main() {
+       ↑       
+  pkg.make_wibble()
+}
+
+
+----- AFTER ACTION
+
+import package as pkg
+
+pub fn main() -> pkg.Wibble {
+  pkg.make_wibble()
+}
diff --git a/compiler-core/src/parse/snapshots/gleam_core__parse__tests__const_string_concat.snap b/compiler-core/src/parse/snapshots/gleam_core__parse__tests__const_string_concat.snap
@@ -100,6 +100,7 @@ Parsed {
             imported_modules: {},
             type_variables: {},
             local_value_constructors: {},
+            reexport_aliases: {},
         },
         unused_definition_positions: {},
     },
diff --git a/compiler-core/src/parse/snapshots/gleam_core__parse__tests__deprecation_attribute_on_type_variant.snap b/compiler-core/src/parse/snapshots/gleam_core__parse__tests__deprecation_attribute_on_type_variant.snap
@@ -69,6 +69,7 @@ Parsed {
             imported_modules: {},
             type_variables: {},
             local_value_constructors: {},
+            reexport_aliases: {},
         },
         unused_definition_positions: {},
     },
diff --git a/compiler-core/src/parse/snapshots/gleam_core__parse__tests__import_type.snap b/compiler-core/src/parse/snapshots/gleam_core__parse__tests__import_type.snap
@@ -69,6 +69,7 @@ Parsed {
             imported_modules: {},
             type_variables: {},
             local_value_constructors: {},
+            reexport_aliases: {},
         },
         unused_definition_positions: {},
     },
diff --git a/compiler-core/src/parse/snapshots/gleam_core__parse__tests__private_opaque_type_is_parsed.snap b/compiler-core/src/parse/snapshots/gleam_core__parse__tests__private_opaque_type_is_parsed.snap
@@ -53,6 +53,7 @@ Parsed {
             imported_modules: {},
             type_variables: {},
             local_value_constructors: {},
+            reexport_aliases: {},
         },
         unused_definition_positions: {},
     },
diff --git a/compiler-core/src/parse/snapshots/gleam_core__parse__tests__record_access_no_label.snap b/compiler-core/src/parse/snapshots/gleam_core__parse__tests__record_access_no_label.snap
@@ -171,6 +171,7 @@ Parsed {
             imported_modules: {},
             type_variables: {},
             local_value_constructors: {},
+            reexport_aliases: {},
         },
         unused_definition_positions: {},
     },
diff --git a/compiler-core/src/type_/environment.rs b/compiler-core/src/type_/environment.rs
@@ -113,21 +113,10 @@ impl<'a> Environment<'a> {
             .get(PRELUDE_MODULE_NAME)
             .expect("Unable to find prelude in importable modules");
 
-        let mut names = Names::new();
-        for name in prelude.values.keys() {
-            names.named_constructor_in_scope(
-                PRELUDE_MODULE_NAME.into(),
-                name.clone(),
-                name.clone(),
-            );
-        }
-
-        for name in prelude.types.keys() {
-            names.named_type_in_scope(PRELUDE_MODULE_NAME.into(), name.clone(), name.clone());
-        }
+        let names = Self::build_names(&current_package, prelude, importable_modules);
 
         Self {
-            current_package: current_package.clone(),
+            current_package,
             gleam_version,
             previous_id: ids.next(),
             ids,
@@ -153,6 +142,49 @@ impl<'a> Environment<'a> {
             dev_dependencies,
         }
     }
+
+    fn build_names(
+        current_package: &str,
+        prelude: &ModuleInterface,
+        importable_modules: &im::HashMap<EcoString, ModuleInterface>,
+    ) -> Names {
+        let mut names = Names::new();
+
+        // Insert prelude types and values into scope
+        for name in prelude.values.keys() {
+            names.named_constructor_in_scope(
+                PRELUDE_MODULE_NAME.into(),
+                name.clone(),
+                name.clone(),
+            );
+        }
+        for name in prelude.types.keys() {
+            names.named_type_in_scope(PRELUDE_MODULE_NAME.into(), name.clone(), name.clone());
+        }
+
+        // Find potential type aliases which reexport internal types
+        for module in importable_modules.values() {
+            // Internal types are accessibly within the package they are defined,
+            // so it doesn't make sense to look for reexports within the same
+            // package.
+            if module.package == current_package {
+                continue;
+            }
+            // Internal modules are not part of the public API so they are also
+            // not considered.
+            if module.is_internal {
+                continue;
+            }
+            for (alias_name, alias) in module.type_aliases.iter() {
+                // An alias can only be a public reexport if it is public.
+                if alias.publicity.is_public() {
+                    names.maybe_register_reexport_alias(&module.package, alias_name, alias);
+                }
+            }
+        }
+
+        names
+    }
 }
 
 #[derive(Debug)]
diff --git a/compiler-core/src/type_/printer.rs b/compiler-core/src/type_/printer.rs

Original file line number	Diff line number	Diff line change
`@@ -5014,7 +5014,7 @@ fn pretty_constructor_name(`
`5014`	`5014`	`.names`
`5015`	`5015`	`.named_constructor(constructor_module, constructor_name)`
`5016`	`5016`	`{`
`5017`		`- type_::printer::NameContextInformation::Unimported(_) => None,`
	`5017`	`+ type_::printer::NameContextInformation::Unimported(_, _) => None,`
`5018`	`5018`	`type_::printer::NameContextInformation::Unqualified(constructor_name) => {`
`5019`	`5019`	`Some(eco_format!("{constructor_name}"))`
`5020`	`5020`	`}`