[move][ide] Change parsing / expansion to report IDE suggestions for …

…missing types (#18744)

## Description 

This modifies the parser to build `UnresolvedError` for types that don't
parse, and then uses those during expansion to provide IDE alias
information at those locations.

## Test plan 

New IDE tests, plus everything else still works as expected.

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:
- [ ] REST API:

external-crates/move/crates/move-compiler/src/expansion/path_expander.rs

@@ -50,9 +50,8 @@ pub enum Access {
     Module, // Just used for errors
 }
 
-// This trait describes the commands available to handle alias scopes and expanding name access
-// chains. This is used to model both legacy and modern path expansion.
-
+/// This trait describes the commands available to handle alias scopes and expanding name access
+/// chains. This is used to model both legacy and modern path expansion.
 pub trait PathExpander {
     // Push a new innermost alias scope
     fn push_alias_scope(

external-crates/move/crates/move-compiler/src/expansion/translate.rs

@@ -221,6 +221,18 @@ impl<'env, 'map> Context<'env, 'map> {
             .name_access_chain_to_module_ident(inner_context, chain)
     }
 
+    fn error_ide_autocomplete_suggestion(&mut self, loc: Loc) {
+        let Context {
+            path_expander,
+            defn_context: inner_context,
+            ..
+        } = self;
+        path_expander
+            .as_mut()
+            .unwrap()
+            .ide_autocomplete_suggestion(inner_context, loc)
+    }
+
     pub fn spec_deprecated(&mut self, loc: Loc, is_error: bool) {
         let diag = self.spec_deprecated_diag(loc, is_error);
         self.env().add_diag(diag);
@@ -2328,7 +2340,11 @@ fn type_(context: &mut Context, sp!(loc, pt_): P::Type) -> E::Type {
             let result = type_(context, *result);
             ET::Fun(args, Box::new(result))
         }
-        PT::UnresolvedError => ET::UnresolvedError,
+        PT::UnresolvedError => {
+            // Treat an unresolved error as a leading access
+            context.error_ide_autocomplete_suggestion(loc);
+            ET::UnresolvedError
+        }
     };
     sp(loc, t_)
 }

external-crates/move/crates/move-compiler/src/parser/syntax.rs

@@ -2941,21 +2941,28 @@ fn parse_type_(
             ));
         }
         _ => {
-            let tn = if whitespace_sensitive_ty_args {
-                parse_name_access_chain(
-                    context,
-                    /* macros */ false,
-                    /* tyargs */ true,
-                    || "a type name",
-                )?
+            if context.at_stop_set() {
+                context
+                    .env
+                    .add_diag(*unexpected_token_error(context.tokens, "a type name"));
+                Type_::UnresolvedError
             } else {
-                parse_name_access_chain_with_tyarg_whitespace(
-                    context,
-                    /* macros */ false,
-                    || "a type name",
-                )?
-            };
-            Type_::Apply(Box::new(tn))
+                let tn = if whitespace_sensitive_ty_args {
+                    parse_name_access_chain(
+                        context,
+                        /* macros */ false,
+                        /* tyargs */ true,
+                        || "a type name",
+                    )?
+                } else {
+                    parse_name_access_chain_with_tyarg_whitespace(
+                        context,
+                        /* macros */ false,
+                        || "a type name",
+                    )?
+                };
+                Type_::Apply(Box::new(tn))
+            }
         }
     };
     let end_loc = context.tokens.previous_end_loc();

external-crates/move/crates/move-compiler/tests/move_2024/ide_mode/missing_type_suggestions.exp

@@ -0,0 +1,68 @@
+warning[W09001]: unused alias
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:7:16
+  │
+7 │     use a::m::{Self, S, A};
+  │                ^^^^ Unused 'use' of alias 'm'. Consider removing it
+  │
+  = This warning can be suppressed with '#[allow(unused_use)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+warning[W09001]: unused alias
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:7:22
+  │
+7 │     use a::m::{Self, S, A};
+  │                      ^ Unused 'use' of alias 'S'. Consider removing it
+  │
+  = This warning can be suppressed with '#[allow(unused_use)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+warning[W09001]: unused alias
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:7:25
+  │
+7 │     use a::m::{Self, S, A};
+  │                         ^ Unused 'use' of alias 'A'. Consider removing it
+  │
+  = This warning can be suppressed with '#[allow(unused_use)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+warning[W09002]: unused variable
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:9:18
+  │
+9 │     public fun p(a:
+  │                  ^ Unused parameter 'a'. Consider removing or prefixing with an underscore: '_a'
+  │
+  = This warning can be suppressed with '#[allow(unused_variable)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:11:5
+   │
+ 9 │     public fun p(a:
+   │                 - To match this '('
+10 │ 
+11 │     public fun q():
+   │     ^ Expected ')'
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:11:5
+   │
+11 │     public fun q():
+   │     ^^^^^^
+   │     │
+   │     Unexpected 'public'
+   │     Expected a type name
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:12:1
+   │
+12 │ }
+   │ ^
+   │ │
+   │ Unexpected '}'
+   │ Expected a type name
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:14:1
+   │
+14 │ 
+   │ ^
+   │ 
+   │ Unexpected end-of-file
+   │ Expected '{'
+

external-crates/move/crates/move-compiler/tests/move_2024/ide_mode/missing_type_suggestions.ide.exp

@@ -0,0 +1,142 @@
+note[I15006]: IDE path autocomplete
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:1:1
+  │  
+1 │ ╭ module a::m {
+2 │ │     public struct S<T> { x: T }
+3 │ │     public struct A {}
+4 │ │ }
+  │ ╰─^ Possible in-scope names
+  │  
+  = members: 'A -> a::m::A', 'Option -> std::option::Option', or 'S -> a::m::S'
+  = modules: 'Self -> a::m', 'option -> std::option', or 'vector -> std::vector'
+  = addresses: 'B -> 0x42', 'K -> 0x19', 'M -> 0x40', 'a -> 0x44', 'b -> 0x45', 'k -> 0x19', 'std -> 0x1', or 'sui -> 0x2'
+  = type params: 
+
+warning[W09009]: unused struct field
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:2:26
+  │
+2 │     public struct S<T> { x: T }
+  │                          ^ The 'x' field of the 'S' type is unused
+  │
+  = This warning can be suppressed with '#[allow(unused_field)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+note[I15006]: IDE path autocomplete
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:2:29
+  │
+2 │     public struct S<T> { x: T }
+  │                             ^ Possible in-scope names
+  │
+  = members: 'A -> a::m::A', 'Option -> std::option::Option', or 'S -> a::m::S'
+  = modules: 'Self -> a::m', 'option -> std::option', or 'vector -> std::vector'
+  = addresses: 'B -> 0x42', 'K -> 0x19', 'M -> 0x40', 'a -> 0x44', 'b -> 0x45', 'k -> 0x19', 'std -> 0x1', or 'sui -> 0x2'
+  = type params: 'T'
+
+note[I15006]: IDE path autocomplete
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:6:1
+   │  
+ 6 │ ╭ module a::test {
+ 7 │ │     use a::m::{Self, S, A};
+ 8 │ │ 
+ 9 │ │     public fun p(a:
+10 │ │ 
+11 │ │     public fun q():
+12 │ │ }
+   │ ╰─^ Possible in-scope names
+   │  
+   = members: 'A -> a::m::A', 'Option -> std::option::Option', 'S -> a::m::S', 'p -> a::test::p', or 'q -> a::test::q'
+   = modules: 'Self -> a::test', 'm -> a::m', 'option -> std::option', or 'vector -> std::vector'
+   = addresses: 'B -> 0x42', 'K -> 0x19', 'M -> 0x40', 'a -> 0x44', 'b -> 0x45', 'k -> 0x19', 'std -> 0x1', or 'sui -> 0x2'
+   = type params: 
+
+warning[W09001]: unused alias
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:7:16
+  │
+7 │     use a::m::{Self, S, A};
+  │                ^^^^ Unused 'use' of alias 'm'. Consider removing it
+  │
+  = This warning can be suppressed with '#[allow(unused_use)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+warning[W09001]: unused alias
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:7:22
+  │
+7 │     use a::m::{Self, S, A};
+  │                      ^ Unused 'use' of alias 'S'. Consider removing it
+  │
+  = This warning can be suppressed with '#[allow(unused_use)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+warning[W09001]: unused alias
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:7:25
+  │
+7 │     use a::m::{Self, S, A};
+  │                         ^ Unused 'use' of alias 'A'. Consider removing it
+  │
+  = This warning can be suppressed with '#[allow(unused_use)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+warning[W09002]: unused variable
+  ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:9:18
+  │
+9 │     public fun p(a:
+  │                  ^ Unused parameter 'a'. Consider removing or prefixing with an underscore: '_a'
+  │
+  = This warning can be suppressed with '#[allow(unused_variable)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+note[I15006]: IDE path autocomplete
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:11:5
+   │  
+ 9 │ │     public fun p(a:
+   │ ╰───────────────────^ Possible in-scope names
+10 │   
+11 │ ╭     public fun q():
+   │  
+   = members: 'A -> a::m::A', 'Option -> std::option::Option', 'S -> a::m::S', 'p -> a::test::p', or 'q -> a::test::q'
+   = modules: 'Self -> a::test', 'm -> a::m', 'option -> std::option', or 'vector -> std::vector'
+   = addresses: 'B -> 0x42', 'K -> 0x19', 'M -> 0x40', 'a -> 0x44', 'b -> 0x45', 'k -> 0x19', 'std -> 0x1', or 'sui -> 0x2'
+   = type params: 
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:11:5
+   │
+ 9 │     public fun p(a:
+   │                 - To match this '('
+10 │ 
+11 │     public fun q():
+   │     ^ Expected ')'
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:11:5
+   │
+11 │     public fun q():
+   │     ^^^^^^
+   │     │
+   │     Unexpected 'public'
+   │     Expected a type name
+
+note[I15006]: IDE path autocomplete
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:11:16
+   │
+11 │     public fun q():
+   │                ^ Possible in-scope names
+   │
+   = members: 'A -> a::m::A', 'Option -> std::option::Option', 'S -> a::m::S', 'p -> a::test::p', or 'q -> a::test::q'
+   = modules: 'Self -> a::test', 'm -> a::m', 'option -> std::option', or 'vector -> std::vector'
+   = addresses: 'B -> 0x42', 'K -> 0x19', 'M -> 0x40', 'a -> 0x44', 'b -> 0x45', 'k -> 0x19', 'std -> 0x1', or 'sui -> 0x2'
+   = type params: 
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:12:1
+   │
+12 │ }
+   │ ^
+   │ │
+   │ Unexpected '}'
+   │ Expected a type name
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/missing_type_suggestions.move:14:1
+   │
+14 │ 
+   │ ^
+   │ 
+   │ Unexpected end-of-file
+   │ Expected '{'
+

external-crates/move/crates/move-compiler/tests/move_2024/ide_mode/missing_type_suggestions.move

@@ -0,0 +1,13 @@
+module a::m {
+    public struct S<T> { x: T }
+    public struct A {}
+}
+
+module a::test {
+    use a::m::{Self, S, A};
+
+    public fun p(a:
+
+    public fun q():
+}
+

external-crates/move/crates/move-compiler/tests/move_2024/ide_mode/partial_type_suggestions.exp

@@ -0,0 +1,66 @@
+warning[W09001]: unused alias
+  ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:7:16
+  │
+7 │     use a::m::{Self, S, A};
+  │                ^^^^ Unused 'use' of alias 'm'. Consider removing it
+  │
+  = This warning can be suppressed with '#[allow(unused_use)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+error[E03008]: too few type arguments
+  ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:9:28
+  │
+9 │     public fun p(): vector<S
+  │                            ^ Invalid instantiation of 'a::m::S'. Expected 1 type argument(s) but got 0
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:11:5
+   │
+ 9 │     public fun p(): vector<S
+   │                           - To match this '<'
+10 │ 
+11 │     public fun q(x: S<A
+   │     ^ Expected '>'
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:11:5
+   │
+11 │     public fun q(x: S<A
+   │     ^^^^^^
+   │     │
+   │     Unexpected 'public'
+   │     Expected '{'
+
+warning[W09002]: unused variable
+   ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:11:18
+   │
+11 │     public fun q(x: S<A
+   │                  ^ Unused parameter 'x'. Consider removing or prefixing with an underscore: '_x'
+   │
+   = This warning can be suppressed with '#[allow(unused_variable)]' applied to the 'module' or module member ('const', 'fun', or 'struct')
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:12:1
+   │
+11 │     public fun q(x: S<A
+   │                      - To match this '<'
+12 │ }
+   │ ^ Expected '>'
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:12:1
+   │
+12 │ }
+   │ ^
+   │ │
+   │ Unexpected '}'
+   │ Expected ',' or ')'
+
+error[E01002]: unexpected token
+   ┌─ tests/move_2024/ide_mode/partial_type_suggestions.move:14:1
+   │
+11 │     public fun q(x: S<A
+   │                 - To match this '('
+   ·
+14 │ 
+   │ ^ Expected ')'
+