add phantom_data adt flag

Author: basil-cow

chalk-integration/src/lowering.rs

@@ -1001,6 +1001,7 @@ impl LowerAdtDefn for StructDefn {
         let flags = rust_ir::AdtFlags {
             upstream: self.flags.upstream,
             fundamental: self.flags.fundamental,
+            phantom_data: self.flags.phantom_data,
         };
 
         Ok(rust_ir::AdtDatum {

chalk-parse/src/ast.rs

@@ -41,6 +41,7 @@ pub struct StructDefn {
 pub struct StructFlags {
     pub upstream: bool,
     pub fundamental: bool,
+    pub phantom_data: bool,
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]

chalk-parse/src/parser.lalrpop

@@ -45,6 +45,7 @@ FundamentalKeyword: () = "#" "[" "fundamental" "]";
 NonEnumerableKeyword: () = "#" "[" "non_enumerable" "]";
 CoinductiveKeyword: () = "#" "[" "coinductive" "]";
 ObjectSafeKeyword: () = "#" "[" "object_safe" "]";
+PhantomDataKeyword: () = "#" "[" "phantom_data" "]";
 
 WellKnownTrait: WellKnownTrait = {
      "#" "[" "lang" "(" "sized" ")" "]" => WellKnownTrait::Sized,
@@ -54,7 +55,8 @@ WellKnownTrait: WellKnownTrait = {
 };
 
 StructDefn: StructDefn = {
-    <upstream:UpstreamKeyword?> <fundamental:FundamentalKeyword?> "struct" <n:Id><p:Angle<VariableKind>>
+    <upstream:UpstreamKeyword?> <fundamental:FundamentalKeyword?> <phantom_data:PhantomDataKeyword?>
+        "struct" <n:Id><p:Angle<VariableKind>>
         <w:QuantifiedWhereClauses> "{" <f:Fields> "}" => StructDefn
     {
         name: n,
@@ -64,6 +66,7 @@ StructDefn: StructDefn = {
         flags: StructFlags {
             upstream: upstream.is_some(),
             fundamental: fundamental.is_some(),
+            phantom_data: phantom_data.is_some(),
         },
     }
 };

chalk-solve/src/rust_ir.rs

@@ -101,6 +101,7 @@ pub struct AdtDatumBound<I: Interner> {
 pub struct AdtFlags {
     pub upstream: bool,
     pub fundamental: bool,
+    pub phantom_data: bool,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]

tests/lowering/mod.rs

@@ -686,3 +686,13 @@ fn lifetime_outlives() {
         }
     }
 }
+
+#[test]
+fn phantom_data() {
+    lowering_success! {
+        program {
+            #[phantom_data]
+            struct PhantomData<T> {}
+        }
+    }
+}