Implement pattern_type macro

Author: Veykril

crates/hir-def/src/expr_store/body.rs

@@ -8,7 +8,7 @@ use syntax::ast;
 use triomphe::Arc;
 
 use crate::{
-    DefWithBodyId, HasModule,
+    DefWithBodyId, ExpressionStoreOwnerId, HasModule,
     db::DefDatabase,
     expr_store::{
         ExpressionStore, ExpressionStoreSourceMap, SelfParamPtr, lower::lower_body, pretty,
@@ -139,7 +139,7 @@ impl Body {
     pub fn pretty_print_pat(
         &self,
         db: &dyn DefDatabase,
-        owner: DefWithBodyId,
+        owner: ExpressionStoreOwnerId,
         pat: PatId,
         oneline: bool,
         edition: Edition,

crates/hir-def/src/expr_store/lower.rs

@@ -720,6 +720,10 @@ impl<'db> ExprCollector<'db> {
             ast::Type::DynTraitType(inner) => TypeRef::DynTrait(
                 self.type_bounds_from_ast(inner.type_bound_list(), impl_trait_lower_fn),
             ),
+            ast::Type::PatternType(inner) => TypeRef::PatternType(
+                self.lower_type_ref_opt(inner.ty(), impl_trait_lower_fn),
+                self.collect_pat_top(inner.pat()),
+            ),
             ast::Type::MacroType(mt) => match mt.macro_call() {
                 Some(mcall) => {
                     let macro_ptr = AstPtr::new(&mcall);

crates/hir-def/src/expr_store/pretty.rs

@@ -420,7 +420,7 @@ pub fn print_expr_hir(
 pub fn print_pat_hir(
     db: &dyn DefDatabase,
     store: &ExpressionStore,
-    _owner: DefWithBodyId,
+    _owner: ExpressionStoreOwnerId,
     pat: PatId,
     oneline: bool,
     edition: Edition,
@@ -1340,6 +1340,11 @@ impl Printer<'_> {
                 w!(self, "dyn ");
                 self.print_type_bounds(bounds);
             }
+            TypeRef::PatternType(ty, pat) => {
+                self.print_type_ref(*ty);
+                w!(self, " is ");
+                self.print_pat(*pat);
+            }
         }
     }
 

crates/hir-def/src/hir/type_ref.rs

@@ -12,7 +12,7 @@ use crate::{
         ExpressionStore,
         path::{GenericArg, Path},
     },
-    hir::ExprId,
+    hir::{ExprId, PatId},
 };
 
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
@@ -142,6 +142,7 @@ pub enum TypeRef {
     ImplTrait(ThinVec<TypeBound>),
     DynTrait(ThinVec<TypeBound>),
     TypeParam(TypeParamId),
+    PatternType(TypeRefId, PatId),
     Error,
 }
 
@@ -221,6 +222,7 @@ impl TypeRef {
                     }
                 }
                 TypeRef::Path(path) => go_path(path, f, map),
+                TypeRef::PatternType(ty, _) => go(*ty, f, map),
                 TypeRef::Never | TypeRef::Placeholder | TypeRef::Error | TypeRef::TypeParam(_) => {}
             };
         }

crates/hir-def/src/lib.rs

@@ -891,6 +891,12 @@ impl From<VariantId> for ExpressionStoreOwnerId {
     }
 }
 
+impl From<ImplId> for ExpressionStoreOwnerId {
+    fn from(id: ImplId) -> Self {
+        ExpressionStoreOwnerId::Signature(id.into())
+    }
+}
+
 impl GenericDefId {
     pub fn file_id_and_params_of(
         self,

crates/hir-expand/src/builtin/derive_macro.rs

@@ -1462,6 +1462,9 @@ fn coerce_pointee_expand(
             ast::Type::TupleType(ty) => {
                 any_long(ty.fields(), |ty| substitute_type_in_bound(ty, param_name, replacement))
             }
+            ast::Type::PatternType(ty) => {
+                ty.ty().is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
+            }
             ast::Type::InferType(_) | ast::Type::MacroType(_) | ast::Type::NeverType(_) => false,
         };
 

crates/hir-expand/src/builtin/fn_macro.rs

@@ -137,6 +137,7 @@ register_builtin! {
     (const_format_args, ConstFormatArgs) => format_args_expand,
     (format_args_nl, FormatArgsNl) => format_args_nl_expand,
     (quote, Quote) => quote_expand,
+    (pattern_type, PatternType) => pattern_type_expand,
 
     EagerExpander:
     (compile_error, CompileError) => compile_error_expand,
@@ -994,3 +995,14 @@ fn unescape_str(s: &str) -> Cow<'_, str> {
         Cow::Borrowed(s)
     }
 }
+
+fn pattern_type_expand(
+    _db: &dyn ExpandDatabase,
+    _arg_id: MacroCallId,
+    tt: &tt::TopSubtree,
+    call_site: Span,
+) -> ExpandResult<tt::TopSubtree> {
+    let mut tt = tt.clone();
+    tt.set_top_subtree_delimiter_kind(tt::DelimiterKind::Invisible);
+    ExpandResult::ok(quote! {call_site => in #tt })
+}