16 files changed, 234 insertions, 9 deletions

diff --git a/Cargo.lock b/Cargo.lock
index fbb79e01f..891cff55e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1827,9 +1827,9 @@ checksum = "56dee185309b50d1f11bfedef0fe6d036842e3fb77413abef29f8f8d1c5d4c1c"
 
 [[package]]
 name = "ungrammar"
-version = "1.4.0"
+version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "68951379f3ced25754472ca5addbf74d7dab58c9818f49290a3d8caa3ab44fb7"
+checksum = "c11bffada52edc8f2a56160b286ea4640acf90ffcb21bded361ccb8ed43a1457"
 
 [[package]]
 name = "unicase"
diff --git a/crates/completion/src/completions/qualified_path.rs b/crates/completion/src/completions/qualified_path.rs
index 1300f00b2..882c4dcbc 100644
--- a/crates/completion/src/completions/qualified_path.rs
+++ b/crates/completion/src/completions/qualified_path.rs
@@ -118,6 +118,12 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                     _ => return,
                 };
 
+                if let Some(Adt::Enum(e)) = ty.as_adt() {
+                    for variant in e.variants(ctx.db) {
+                        acc.add_enum_variant(ctx, variant, None);
+                    }
+                }
+
                 let traits_in_scope = ctx.scope.traits_in_scope();
                 let mut seen = FxHashSet::default();
                 ty.iterate_path_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, item| {
@@ -752,4 +758,27 @@ fn main() {
             "#]],
         );
     }
+
+    #[test]
+    fn completes_self_enum() {
+        check(
+            r#"
+enum Foo {
+    Bar,
+    Baz,
+}
+
+impl Foo {
+    fn foo(self) {
+        Self::<|>
+    }
+}
+"#,
+            expect![[r#"
+                ev Bar    ()
+                ev Baz    ()
+                me foo(…) fn foo(self)
+            "#]],
+        );
+    }
 }
diff --git a/crates/completion/src/completions/unqualified_path.rs b/crates/completion/src/completions/unqualified_path.rs
index 099ffb4d4..d09849752 100644
--- a/crates/completion/src/completions/unqualified_path.rs
+++ b/crates/completion/src/completions/unqualified_path.rs
@@ -1,5 +1,7 @@
 //! Completion of names from the current scope, e.g. locals and imported items.
 
+use std::iter;
+
 use either::Either;
 use hir::{Adt, ModPath, ModuleDef, ScopeDef, Type};
 use ide_db::helpers::insert_use::ImportScope;
@@ -50,7 +52,9 @@ pub(crate) fn complete_unqualified_path(acc: &mut Completions, ctx: &CompletionC
 }
 
 fn complete_enum_variants(acc: &mut Completions, ctx: &CompletionContext, ty: &Type) {
-    if let Some(Adt::Enum(enum_data)) = ty.as_adt() {
+    if let Some(Adt::Enum(enum_data)) =
+        iter::successors(Some(ty.clone()), |ty| ty.remove_ref()).last().and_then(|ty| ty.as_adt())
+    {
         let variants = enum_data.variants(ctx.db);
 
         let module = if let Some(module) = ctx.scope.module() {
@@ -701,6 +705,7 @@ fn main() { <|> }
             "#]],
         );
     }
+
     #[test]
     fn completes_enum_variant_matcharm() {
         check(
@@ -722,6 +727,26 @@ fn main() {
     }
 
     #[test]
+    fn completes_enum_variant_matcharm_ref() {
+        check(
+            r#"
+enum Foo { Bar, Baz, Quux }
+
+fn main() {
+    let foo = Foo::Quux;
+    match &foo { Qu<|> }
+}
+"#,
+            expect![[r#"
+                ev Foo::Bar  ()
+                ev Foo::Baz  ()
+                ev Foo::Quux ()
+                en Foo
+            "#]],
+        )
+    }
+
+    #[test]
     fn completes_enum_variant_iflet() {
         check(
             r#"
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 0f404be1b..978c3a324 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -933,7 +933,9 @@ impl ExprCollector<'_> {
                 Pat::Box { inner }
             }
             // FIXME: implement
-            ast::Pat::RangePat(_) | ast::Pat::MacroPat(_) => Pat::Missing,
+            ast::Pat::RangePat(_) | ast::Pat::MacroPat(_) | ast::Pat::ConstBlockPat(_) => {
+                Pat::Missing
+            }
         };
         let ptr = AstPtr::new(&pat);
         self.alloc_pat(pattern, Either::Left(ptr))
diff --git a/crates/parser/src/grammar/expressions/atom.rs b/crates/parser/src/grammar/expressions/atom.rs
index e897d5a52..c7a3556a7 100644
--- a/crates/parser/src/grammar/expressions/atom.rs
+++ b/crates/parser/src/grammar/expressions/atom.rs
@@ -46,6 +46,7 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
         T![continue],
         T![async],
         T![try],
+        T![const],
         T![loop],
         T![for],
         LIFETIME_IDENT,
@@ -115,6 +116,14 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
             block_expr(p);
             m.complete(p, EFFECT_EXPR)
         }
+        // test const_block
+        // fn f() { const { } }
+        T![const] if la == T!['{'] => {
+            let m = p.start();
+            p.bump(T![const]);
+            block_expr(p);
+            m.complete(p, EFFECT_EXPR)
+        }
         T!['{'] => {
             // test for_range_from
             // fn foo() {
diff --git a/crates/parser/src/grammar/items.rs b/crates/parser/src/grammar/items.rs
index 8999829b4..72b73f891 100644
--- a/crates/parser/src/grammar/items.rs
+++ b/crates/parser/src/grammar/items.rs
@@ -96,7 +96,10 @@ pub(super) fn maybe_item(p: &mut Parser, m: Marker) -> Result<(), Marker> {
     let mut has_mods = false;
 
     // modifiers
-    has_mods |= p.eat(T![const]);
+    if p.at(T![const]) && p.nth(1) != T!['{'] {
+        p.eat(T![const]);
+        has_mods = true;
+    }
 
     // test_err async_without_semicolon
     // fn foo() { let _ = async {} }
@@ -167,7 +170,7 @@ pub(super) fn maybe_item(p: &mut Parser, m: Marker) -> Result<(), Marker> {
             m.complete(p, TRAIT);
         }
 
-        T![const] => {
+        T![const] if p.nth(1) != T!['{'] => {
             consts::konst(p, m);
         }
 
diff --git a/crates/parser/src/grammar/patterns.rs b/crates/parser/src/grammar/patterns.rs
index 7e7f73dee..b53d5749f 100644
--- a/crates/parser/src/grammar/patterns.rs
+++ b/crates/parser/src/grammar/patterns.rs
@@ -89,6 +89,7 @@ fn atom_pat(p: &mut Parser, recovery_set: TokenSet) -> Option<CompletedMarker> {
     let m = match p.nth(0) {
         T![box] => box_pat(p),
         T![ref] | T![mut] => ident_pat(p, true),
+        T![const] => const_block_pat(p),
         IDENT => match p.nth(1) {
             // Checks the token after an IDENT to see if a pattern is a path (Struct { .. }) or macro
             // (T![x]).
@@ -386,3 +387,16 @@ fn box_pat(p: &mut Parser) -> CompletedMarker {
     pattern_single(p);
     m.complete(p, BOX_PAT)
 }
+
+// test const_block_pat
+// fn main() {
+//     let const { 15 } = ();
+//     let const { foo(); bar() } = ();
+// }
+fn const_block_pat(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(T![const]));
+    let m = p.start();
+    p.bump(T![const]);
+    expressions::block_expr(p);
+    m.complete(p, CONST_BLOCK_PAT)
+}
diff --git a/crates/parser/src/syntax_kind/generated.rs b/crates/parser/src/syntax_kind/generated.rs
index 980aa5979..f69e71bdb 100644
--- a/crates/parser/src/syntax_kind/generated.rs
+++ b/crates/parser/src/syntax_kind/generated.rs
@@ -170,6 +170,7 @@ pub enum SyntaxKind {
     RANGE_PAT,
     LITERAL_PAT,
     MACRO_PAT,
+    CONST_BLOCK_PAT,
     TUPLE_EXPR,
     ARRAY_EXPR,
     PAREN_EXPR,
diff --git a/crates/syntax/src/ast/generated/nodes.rs b/crates/syntax/src/ast/generated/nodes.rs
index 1588ba93e..c5b80bffe 100644
--- a/crates/syntax/src/ast/generated/nodes.rs
+++ b/crates/syntax/src/ast/generated/nodes.rs
@@ -763,6 +763,7 @@ impl EffectExpr {
     pub fn try_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![try]) }
     pub fn unsafe_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![unsafe]) }
     pub fn async_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![async]) }
+    pub fn const_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![const]) }
     pub fn block_expr(&self) -> Option<BlockExpr> { support::child(&self.syntax) }
 }
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -1251,6 +1252,14 @@ impl TupleStructPat {
     pub fn r_paren_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![')']) }
 }
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ConstBlockPat {
+    pub(crate) syntax: SyntaxNode,
+}
+impl ConstBlockPat {
+    pub fn const_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![const]) }
+    pub fn block_expr(&self) -> Option<BlockExpr> { support::child(&self.syntax) }
+}
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct RecordPatFieldList {
     pub(crate) syntax: SyntaxNode,
 }
@@ -1369,6 +1378,7 @@ pub enum Pat {
     SlicePat(SlicePat),
     TuplePat(TuplePat),
     TupleStructPat(TupleStructPat),
+    ConstBlockPat(ConstBlockPat),
 }
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum FieldList {
@@ -2772,6 +2782,17 @@ impl AstNode for TupleStructPat {
     }
     fn syntax(&self) -> &SyntaxNode { &self.syntax }
 }
+impl AstNode for ConstBlockPat {
+    fn can_cast(kind: SyntaxKind) -> bool { kind == CONST_BLOCK_PAT }
+    fn cast(syntax: SyntaxNode) -> Option<Self> {
+        if Self::can_cast(syntax.kind()) {
+            Some(Self { syntax })
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode { &self.syntax }
+}
 impl AstNode for RecordPatFieldList {
     fn can_cast(kind: SyntaxKind) -> bool { kind == RECORD_PAT_FIELD_LIST }
     fn cast(syntax: SyntaxNode) -> Option<Self> {
@@ -3242,12 +3263,15 @@ impl From<TuplePat> for Pat {
 impl From<TupleStructPat> for Pat {
     fn from(node: TupleStructPat) -> Pat { Pat::TupleStructPat(node) }
 }
+impl From<ConstBlockPat> for Pat {
+    fn from(node: ConstBlockPat) -> Pat { Pat::ConstBlockPat(node) }
+}
 impl AstNode for Pat {
     fn can_cast(kind: SyntaxKind) -> bool {
         match kind {
             IDENT_PAT | BOX_PAT | REST_PAT | LITERAL_PAT | MACRO_PAT | OR_PAT | PAREN_PAT
             | PATH_PAT | WILDCARD_PAT | RANGE_PAT | RECORD_PAT | REF_PAT | SLICE_PAT
-            | TUPLE_PAT | TUPLE_STRUCT_PAT => true,
+            | TUPLE_PAT | TUPLE_STRUCT_PAT | CONST_BLOCK_PAT => true,
             _ => false,
         }
     }
@@ -3268,6 +3292,7 @@ impl AstNode for Pat {
             SLICE_PAT => Pat::SlicePat(SlicePat { syntax }),
             TUPLE_PAT => Pat::TuplePat(TuplePat { syntax }),
             TUPLE_STRUCT_PAT => Pat::TupleStructPat(TupleStructPat { syntax }),
+            CONST_BLOCK_PAT => Pat::ConstBlockPat(ConstBlockPat { syntax }),
             _ => return None,
         };
         Some(res)
@@ -3289,6 +3314,7 @@ impl AstNode for Pat {
             Pat::SlicePat(it) => &it.syntax,
             Pat::TuplePat(it) => &it.syntax,
             Pat::TupleStructPat(it) => &it.syntax,
+            Pat::ConstBlockPat(it) => &it.syntax,
         }
     }
 }
@@ -4137,6 +4163,11 @@ impl std::fmt::Display for TupleStructPat {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
+impl std::fmt::Display for ConstBlockPat {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Display::fmt(self.syntax(), f)
+    }
+}
 impl std::fmt::Display for RecordPatFieldList {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index ba7e5d2fb..cafa4c198 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -4,6 +4,11 @@
 //! Note that all functions here intended to be stupid constructors, which just
 //! assemble a finish node from immediate children. If you want to do something
 //! smarter than that, it probably doesn't belong in this module.
+//!
+//! Keep in mind that `from_text` functions should be kept private. The public
+//! API should require to assemble every node piecewise. The trick of
+//! `parse(format!())` we use internally is an implementation detail -- long
+//! term, it will be replaced with direct tree manipulation.
 use itertools::Itertools;
 use stdx::format_to;
 
@@ -16,7 +21,8 @@ pub fn name(text: &str) -> ast::Name {
 pub fn name_ref(text: &str) -> ast::NameRef {
     ast_from_text(&format!("fn f() {{ {}; }}", text))
 }
-
+// FIXME: replace stringly-typed constructor with a family of typed ctors, a-la
+// `expr_xxx`.
 pub fn ty(text: &str) -> ast::Type {
     ast_from_text(&format!("impl {} for D {{}};", text))
 }
diff --git a/crates/syntax/test_data/parser/inline/ok/0156_const_block_pat.rast b/crates/syntax/test_data/parser/inline/ok/0156_const_block_pat.rast
new file mode 100644
index 000000000..8ff4822c4
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0156_const_block_pat.rast
@@ -0,0 +1,76 @@
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "main"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n    "
+      [email protected]
+        [email protected] "let"
+        [email protected] " "
+        [email protected]
+          [email protected] "const"
+          [email protected] " "
+          [email protected]
+            [email protected] "{"
+            [email protected] " "
+            [email protected]
+              [email protected] "15"
+            [email protected] " "
+            [email protected] "}"
+        [email protected] " "
+        [email protected] "="
+        [email protected] " "
+        [email protected]
+          [email protected] "("
+          [email protected] ")"
+        [email protected] ";"
+      [email protected] "\n    "
+      [email protected]
+        [email protected] "let"
+        [email protected] " "
+        [email protected]
+          [email protected] "const"
+          [email protected] " "
+          [email protected]
+            [email protected] "{"
+            [email protected] " "
+            [email protected]
+              [email protected]
+                [email protected]
+                  [email protected]
+                    [email protected]
+                      [email protected]
+                        [email protected] "foo"
+                [email protected]
+                  [email protected] "("
+                  [email protected] ")"
+              [email protected] ";"
+            [email protected] " "
+            [email protected]
+              [email protected]
+                [email protected]
+                  [email protected]
+                    [email protected]
+                      [email protected] "bar"
+              [email protected]
+                [email protected] "("
+                [email protected] ")"
+            [email protected] " "
+            [email protected] "}"
+        [email protected] " "
+        [email protected] "="
+        [email protected] " "
+        [email protected]
+          [email protected] "("
+          [email protected] ")"
+        [email protected] ";"
+      [email protected] "\n"
+      [email protected] "}"
+  [email protected] "\n"
diff --git a/crates/syntax/test_data/parser/inline/ok/0156_const_block_pat.rs b/crates/syntax/test_data/parser/inline/ok/0156_const_block_pat.rs
new file mode 100644
index 000000000..dce9defac
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0156_const_block_pat.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let const { 15 } = ();
+    let const { foo(); bar() } = ();
+}
diff --git a/crates/syntax/test_data/parser/inline/ok/0157_const_block.rast b/crates/syntax/test_data/parser/inline/ok/0157_const_block.rast
new file mode 100644
index 000000000..d5d2c8fe3
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0157_const_block.rast
@@ -0,0 +1,23 @@
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "f"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] " "
+      [email protected]
+        [email protected] "const"
+        [email protected] " "
+        [email protected]
+          [email protected] "{"
+          [email protected] " "
+          [email protected] "}"
+      [email protected] " "
+      [email protected] "}"
+  [email protected] "\n"
diff --git a/crates/syntax/test_data/parser/inline/ok/0157_const_block.rs b/crates/syntax/test_data/parser/inline/ok/0157_const_block.rs
new file mode 100644
index 000000000..a2e3565a3
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0157_const_block.rs
@@ -0,0 +1 @@
+fn f() { const { } }
diff --git a/xtask/Cargo.toml b/xtask/Cargo.toml
index 78a0b54ba..96b4ea448 100644
--- a/xtask/Cargo.toml
+++ b/xtask/Cargo.toml
@@ -15,7 +15,7 @@ flate2 = "1.0"
 pico-args = "0.3.1"
 proc-macro2 = "1.0.8"
 quote = "1.0.2"
-ungrammar = "1.4"
+ungrammar = "1.5"
 walkdir = "2.3.1"
 write-json = "0.1.0"
 xshell = "0.1"
diff --git a/xtask/src/ast_src.rs b/xtask/src/ast_src.rs
index a69ced5cc..2b8012bdd 100644
--- a/xtask/src/ast_src.rs
+++ b/xtask/src/ast_src.rs
@@ -132,6 +132,7 @@ pub(crate) const KINDS_SRC: KindsSrc = KindsSrc {
         "RANGE_PAT",
         "LITERAL_PAT",
         "MACRO_PAT",
+        "CONST_BLOCK_PAT",
         // atoms
         "TUPLE_EXPR",
         "ARRAY_EXPR",