[move-compiler] Add public struct type support to the parser (#13917)

## Description 

Add support for `public struct` declarations in the Move 2024 edition.

To my knowledge this is the first backwards incompatible change, so we
need to split off a separate version of the move-stdlib that tracks the
new 2024 edition as well.

The bottom commit of this PR does this, and also refactors the test
runner so we aren't passing so many fields all the time in the test
runner.

## Test Plan 

Added additional tests.

---
If your changes are not user-facing and not a breaking change, you can
skip the following section. Otherwise, please indicate what changed, and
then add to the Release Notes section as highlighted during the release
process.

### Type of Change (Check all that apply)

- [ ] protocol change
- [X] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes

Adds initial `public struct` type visibility support to Move 2024.alpha.
When using the Move 2024.alpha edition you will be required to write
`public` in front of the struct type which will keep the same semantics
as `struct` with no visibility modifiers today (i.e., in the `legacy`
edition), this is to allow for future support of private struct types.

Author: tzakian

move-compiler/src/editions/mod.rs

@@ -29,6 +29,7 @@ pub struct Edition {
 pub enum FeatureGate {
     PublicPackage,
     PostFixAbilities,
+    StructTypeVisibility,
 }
 
 #[derive(PartialEq, Eq, Clone, Copy, Debug, PartialOrd, Ord, Default)]
@@ -48,7 +49,8 @@ pub fn check_feature(
     feature: &FeatureGate,
     loc: Loc,
 ) -> bool {
-    if !edition.supports(feature) {
+    let supports_feature = edition.supports(feature);
+    if !supports_feature {
         let valid_editions = valid_editions_for_feature(feature)
             .into_iter()
             .map(|e| e.to_string())
@@ -69,10 +71,8 @@ pub fn check_feature(
             or via command line flag if invoking the compiler directly.",
         );
         env.add_diag(diag);
-        false
-    } else {
-        true
     }
+    supports_feature
 }
 
 pub fn valid_editions_for_feature(feature: &FeatureGate) -> Vec<Edition> {
@@ -90,8 +90,11 @@ pub fn valid_editions_for_feature(feature: &FeatureGate) -> Vec<Edition> {
 static SUPPORTED_FEATURES: Lazy<BTreeMap<Edition, BTreeSet<FeatureGate>>> =
     Lazy::new(|| BTreeMap::from_iter(Edition::ALL.iter().map(|e| (*e, e.features()))));
 
-const E2024_ALPHA_FEATURES: &[FeatureGate] =
-    &[FeatureGate::PublicPackage, FeatureGate::PostFixAbilities];
+const E2024_ALPHA_FEATURES: &[FeatureGate] = &[
+    FeatureGate::PublicPackage,
+    FeatureGate::PostFixAbilities,
+    FeatureGate::StructTypeVisibility,
+];
 
 impl Edition {
     pub const LEGACY: Self = Self {

move-compiler/src/parser/syntax.rs

@@ -2021,16 +2021,9 @@ fn parse_struct_decl(
         entry,
         native,
     } = modifiers;
-    if let Some(vis) = visibility {
-        let msg = format!(
-            "Invalid struct declaration. Structs cannot have visibility modifiers as they are \
-             always '{}'",
-            Visibility::PUBLIC
-        );
-        context
-            .env
-            .add_diag(diag!(Syntax::InvalidModifier, (vis.loc().unwrap(), msg)));
-    }
+
+    check_struct_visibility(visibility, context);
+
     if let Some(loc) = entry {
         let msg = format!(
             "Invalid constant declaration. '{}' is used only on functions",
@@ -2183,6 +2176,48 @@ fn parse_postfix_ability_declarations(
     Ok(())
 }
 
+fn check_struct_visibility(visibility: Option<Visibility>, context: &mut Context) {
+    let current_package = context.package_name;
+    if let Some(Visibility::Public(loc)) = &visibility {
+        context
+            .env
+            .check_feature(&FeatureGate::StructTypeVisibility, current_package, *loc);
+    }
+
+    let supports_public = context
+        .env
+        .supports_feature(current_package, &FeatureGate::StructTypeVisibility);
+
+    if supports_public {
+        if !matches!(visibility, Some(Visibility::Public(_))) {
+            let (loc, vis_str) = match visibility {
+                Some(vis) => (vis.loc().unwrap(), format!("'{vis}'")),
+                None => {
+                    let loc = current_token_loc(context.tokens);
+                    (loc, "Internal".to_owned())
+                }
+            };
+            let msg = format!(
+                "Invalid struct declaration. {vis_str} struct declarations are not yet supported"
+            );
+            let note = "Visibility annotations are required on struct declarations from the Move 2024 edition onwards.";
+            let mut err = diag!(Syntax::InvalidModifier, (loc, msg));
+            err.add_note(note);
+            context.env.add_diag(err);
+        }
+    } else if let Some(vis) = visibility {
+        let msg = format!(
+            "Invalid struct declaration. Structs cannot have visibility modifiers as they are \
+                always '{}'",
+            Visibility::PUBLIC
+        );
+        let note = "Starting in the Move 2024 edition visibility must be annotated on struct declarations.";
+        let mut err = diag!(Syntax::InvalidModifier, (vis.loc().unwrap(), msg));
+        err.add_note(note);
+        context.env.add_diag(err);
+    }
+}
+
 //**************************************************************************************************
 // Constants
 //**************************************************************************************************

move-compiler/src/shared/mod.rs

@@ -534,6 +534,10 @@ impl CompilationEnv {
         edition_check_feature(self, self.package_config(package).edition, feature, loc)
     }
 
+    pub fn supports_feature(&self, package: Option<Symbol>, feature: &FeatureGate) -> bool {
+        self.package_config(package).edition.supports(feature)
+    }
+
     pub fn package_config(&self, package: Option<Symbol>) -> &PackageConfig {
         package
             .and_then(|p| self.package_configs.get(&p))

move-compiler/tests/move_2024/parser/ability_modifier_infix_and_postfix.exp

@@ -1,8 +1,8 @@
 error[E01003]: invalid modifier
-  ┌─ tests/move_2024/parser/ability_modifier_infix_and_postfix.move:4:34
+  ┌─ tests/move_2024/parser/ability_modifier_infix_and_postfix.move:4:41
   │
-4 │     struct Foo has copy, drop {} has store;
-  │                ---               ^^^ Duplicate ability declaration. Abilities can be declared before or after the field declarations, but not both.
-  │                │                  
-  │                Ability declaration previously given here
+4 │     public struct Foo has copy, drop {} has store;
+  │                       ---               ^^^ Duplicate ability declaration. Abilities can be declared before or after the field declarations, but not both.
+  │                       │                  
+  │                       Ability declaration previously given here
 

move-compiler/tests/move_2024/parser/ability_modifier_infix_and_postfix.move

@@ -1,6 +1,6 @@
 address 0x42 {
 module M {
     // has both prefix and postfix ability declarations
-    struct Foo has copy, drop {} has store;
+    public struct Foo has copy, drop {} has store;
 }
 }

move-compiler/tests/move_2024/parser/ability_modifier_infix_and_postfix_native_struct.exp

@@ -1,9 +1,9 @@
 error[E01002]: unexpected token
-  ┌─ tests/move_2024/parser/ability_modifier_infix_and_postfix_native_struct.move:5:39
+  ┌─ tests/move_2024/parser/ability_modifier_infix_and_postfix_native_struct.move:5:46
   │
-5 │     native struct Foo has copy, drop; has store;
-  │                                       ^^^
-  │                                       │
-  │                                       Unexpected 'has'
-  │                                       Expected a module member: 'spec', 'use', 'friend', 'const', 'fun', or 'struct'
+5 │     public native struct Foo has copy, drop; has store;
+  │                                              ^^^
+  │                                              │
+  │                                              Unexpected 'has'
+  │                                              Expected a module member: 'spec', 'use', 'friend', 'const', 'fun', or 'struct'
 

move-compiler/tests/move_2024/parser/ability_modifier_infix_and_postfix_native_struct.move

@@ -2,6 +2,6 @@ address 0x42 {
 module M {
     // has both invalid declaration since postfix ability declarations
     // are not allowed for native structs
-    native struct Foo has copy, drop; has store;
+    public native struct Foo has copy, drop; has store;
 }
 }

move-compiler/tests/move_2024/parser/ability_modifier_infix_postfix_no_fields.exp

@@ -1,9 +1,9 @@
 error[E01002]: unexpected token
-  ┌─ tests/move_2024/parser/ability_modifier_infix_postfix_no_fields.move:4:38
+  ┌─ tests/move_2024/parser/ability_modifier_infix_postfix_no_fields.move:4:45
   │
-4 │     native struct Foo has copy, drop has store;
-  │                                      ^^^
-  │                                      │
-  │                                      Unexpected 'has'
-  │                                      Expected one of: ',', '{', or ';'
+4 │     public native struct Foo has copy, drop has store;
+  │                                             ^^^
+  │                                             │
+  │                                             Unexpected 'has'
+  │                                             Expected one of: ',', '{', or ';'
 

move-compiler/tests/move_2024/parser/ability_modifier_infix_postfix_no_fields.move

@@ -1,6 +1,6 @@
 address 0x42 {
 module M {
     // has both prefix and invalid postfix ability declarations
-    native struct Foo has copy, drop has store;
+    public native struct Foo has copy, drop has store;
 }
 }

move-compiler/tests/move_2024/parser/ability_modifier_infix_postfix_no_fields_with_comma_sep.exp

@@ -1,6 +1,6 @@
 error[E01002]: unexpected token
-  ┌─ tests/move_2024/parser/ability_modifier_infix_postfix_no_fields_with_comma_sep.move:4:39
+  ┌─ tests/move_2024/parser/ability_modifier_infix_postfix_no_fields_with_comma_sep.move:4:46
   │
-4 │     native struct Foo has copy, drop, has store;
-  │                                       ^^^ Unexpected 'has'. Expected a type ability, one of: 'copy', 'drop', 'store', or 'key'
+4 │     public native struct Foo has copy, drop, has store;
+  │                                              ^^^ Unexpected 'has'. Expected a type ability, one of: 'copy', 'drop', 'store', or 'key'