rust-analyzer

diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 372cf9aba8..3136206761 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs

@@ -639,7 +639,16 @@ impl ExprCollector<'_> {

let type_ref =

stmt.ty().map(|it| Interned::new(TypeRef::from_ast(&self.ctx(), it)));

let initializer = stmt.initializer().map(|e| self.collect_expr(e));

- self.statements_in_scope.push(Statement::Let { pat, type_ref, initializer });

+ let else_branch = stmt

+ .let_else()

+ .and_then(|let_else| let_else.block_expr())

+ .map(|block| self.collect_block(block));

+ self.statements_in_scope.push(Statement::Let {

+ pat,

+ type_ref,

+ initializer,

+ else_branch,

+ });

}

ast::Stmt::ExprStmt(stmt) => {

if let Some(expr) = stmt.expr() {

diff --git a/crates/hir_def/src/body/scope.rs b/crates/hir_def/src/body/scope.rs
index 5d9dd73a12..8a48ad9199 100644
--- a/crates/hir_def/src/body/scope.rs
+++ b/crates/hir_def/src/body/scope.rs

@@ -149,11 +149,15 @@ fn compute_block_scopes(

) {

for stmt in statements {

match stmt {

- Statement::Let { pat, initializer, .. } => {

+ Statement::Let { pat, initializer, else_branch, .. } => {

if let Some(expr) = initializer {

scopes.set_scope(*expr, scope);

compute_expr_scopes(*expr, body, scopes, scope);

}

+ if let Some(expr) = else_branch {

+ scopes.set_scope(*expr, scope);

+ compute_expr_scopes(*expr, body, scopes, scope);

+ }

scope = scopes.new_scope(scope);

scopes.add_bindings(body, scope, *pat);

}

diff --git a/crates/hir_def/src/expr.rs b/crates/hir_def/src/expr.rs
index b508d875e8..17af48b7bf 100644
--- a/crates/hir_def/src/expr.rs
+++ b/crates/hir_def/src/expr.rs

@@ -208,8 +208,16 @@ pub struct RecordLitField {

#[derive(Debug, Clone, Eq, PartialEq)]

pub enum Statement {

- Let { pat: PatId, type_ref: Option<Interned<TypeRef>>, initializer: Option<ExprId> },

- Expr { expr: ExprId, has_semi: bool },

+ Let {

+ pat: PatId,

+ type_ref: Option<Interned<TypeRef>>,

+ initializer: Option<ExprId>,

+ else_branch: Option<ExprId>,

+ },

+ Expr {

+ expr: ExprId,

+ has_semi: bool,

+ },

}

impl Expr {

diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index f5bc898a85..ada5717f1a 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs

@@ -914,7 +914,7 @@ impl<'a> InferenceContext<'a> {

) -> Ty {

for stmt in statements {

match stmt {

- Statement::Let { pat, type_ref, initializer } => {

+ Statement::Let { pat, type_ref, initializer, else_branch } => {

let decl_ty = type_ref

.as_ref()

.map(|tr| self.make_ty(tr))

@@ -931,6 +931,13 @@ impl<'a> InferenceContext<'a> {

}

+ if let Some(expr) = else_branch {

+ self.infer_expr_coerce(

+ *expr,

+ &Expectation::has_type(Ty::new(&Interner, TyKind::Never)),

+ );

+ }

self.infer_pat(*pat, &ty, BindingMode::default());

}

Statement::Expr { expr, .. } => {

diff --git a/crates/hir_ty/src/tests/never_type.rs b/crates/hir_ty/src/tests/never_type.rs
index 335c474df7..8be2b8ec10 100644
--- a/crates/hir_ty/src/tests/never_type.rs
+++ b/crates/hir_ty/src/tests/never_type.rs

@@ -407,3 +407,39 @@ fn diverging_expression_3_break() {

"]],

);

}

+#[test]

+fn let_else_must_diverge() {

+ check_infer_with_mismatches(

+ r#"

+ fn f() {

+ let 1 = 2 else {

+ return;

+ };

+ }

+ "#,

+ expect![[r#"

+ 7..54 '{ ... }; }': ()

+ 17..18 '1': i32

+ 21..22 '2': i32

+ 28..51 '{ ... }': !

+ 38..44 'return': !

+ "#]],

+ );

+ check_infer_with_mismatches(

+ r#"

+ fn f() {

+ let 1 = 2 else {};

+ }

+ "#,

+ expect![[r#"

+ 7..33 '{ ... {}; }': ()

+ 17..18 '1': i32

+ 21..22 '2': i32

+ 28..30 '{}': ()

+ 28..30: expected !, got ()

+ "#]],

+ );

diff --git a/crates/parser/src/grammar/expressions.rs b/crates/parser/src/grammar/expressions.rs
index aa171674ed..54eb96d84e 100644
--- a/crates/parser/src/grammar/expressions.rs
+++ b/crates/parser/src/grammar/expressions.rs

@@ -102,6 +102,16 @@ pub(super) fn stmt(p: &mut Parser, with_semi: StmtWithSemi, prefer_expr: bool) {

expressions::expr(p);

}

+ if p.at(T![else]) {

+ // test let_else

+ // fn f() { let Some(x) = opt else { return }; }

+ let m = p.start();

+ p.bump(T![else]);

+ block_expr(p);

+ m.complete(p, LET_ELSE);

+ }

match with_semi {

StmtWithSemi::No => (),

StmtWithSemi::Optional => {

diff --git a/crates/parser/src/syntax_kind/generated.rs b/crates/parser/src/syntax_kind/generated.rs
index 842d66755c..a9010c0c31 100644
--- a/crates/parser/src/syntax_kind/generated.rs
+++ b/crates/parser/src/syntax_kind/generated.rs

@@ -234,6 +234,7 @@ pub enum SyntaxKind {

NAME,

NAME_REF,

LET_STMT,

+ LET_ELSE,

EXPR_STMT,

GENERIC_PARAM_LIST,

GENERIC_PARAM,

diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index 3c5adb97fb..fba5db9a93 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml

@@ -29,7 +29,7 @@ rayon = "1"

expect-test = "1.1"

proc-macro2 = "1.0.8"

quote = "1.0.2"

-ungrammar = "=1.14.6"

+ungrammar = "=1.14.8"

test_utils = { path = "../test_utils" }

sourcegen = { path = "../sourcegen" }

diff --git a/crates/syntax/src/ast/generated/nodes.rs b/crates/syntax/src/ast/generated/nodes.rs
index f69c873663..15b8371c3e 100644
--- a/crates/syntax/src/ast/generated/nodes.rs
+++ b/crates/syntax/src/ast/generated/nodes.rs

@@ -722,10 +722,20 @@ impl LetStmt {

pub fn ty(&self) -> Option<Type> { support::child(&self.syntax) }

pub fn eq_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![=]) }

pub fn initializer(&self) -> Option<Expr> { support::child(&self.syntax) }

+ pub fn let_else(&self) -> Option<LetElse> { support::child(&self.syntax) }

pub fn semicolon_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![;]) }

}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]

+pub struct LetElse {

+ pub(crate) syntax: SyntaxNode,

+impl LetElse {

+ pub fn else_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![else]) }

+ pub fn block_expr(&self) -> Option<BlockExpr> { support::child(&self.syntax) }

+#[derive(Debug, Clone, PartialEq, Eq, Hash)]

pub struct ArrayExpr {

pub(crate) syntax: SyntaxNode,

}

@@ -2304,6 +2314,17 @@ impl AstNode for LetStmt {

}

fn syntax(&self) -> &SyntaxNode { &self.syntax }

}

+impl AstNode for LetElse {

+ fn can_cast(kind: SyntaxKind) -> bool { kind == LET_ELSE }

+ 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 ArrayExpr {

fn can_cast(kind: SyntaxKind) -> bool { kind == ARRAY_EXPR }

fn cast(syntax: SyntaxNode) -> Option<Self> {

@@ -4320,6 +4341,11 @@ impl std::fmt::Display for LetStmt {

std::fmt::Display::fmt(self.syntax(), f)

}

+impl std::fmt::Display for LetElse {

+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {

+ std::fmt::Display::fmt(self.syntax(), f)

+ }

impl std::fmt::Display for ArrayExpr {

fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {

std::fmt::Display::fmt(self.syntax(), f)

diff --git a/crates/syntax/src/tests/ast_src.rs b/crates/syntax/src/tests/ast_src.rs
index efbb7ca0cc..2344fc59d1 100644
--- a/crates/syntax/src/tests/ast_src.rs
+++ b/crates/syntax/src/tests/ast_src.rs

@@ -198,6 +198,7 @@ pub(crate) const KINDS_SRC: KindsSrc = KindsSrc {

"NAME",

"NAME_REF",

"LET_STMT",

+ "LET_ELSE",

"EXPR_STMT",

"GENERIC_PARAM_LIST",

"GENERIC_PARAM",

diff --git a/crates/syntax/test_data/parser/inline/ok/0194_let_else.rast b/crates/syntax/test_data/parser/inline/ok/0194_let_else.rast
new file mode 100644
index 0000000000..ed0613a38f
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0194_let_else.rast

@@ -0,0 +1,51 @@

[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] "let"

+ [email protected] " "

+ [email protected]

+ [email protected] "Some"

+ [email protected] "("

+ [email protected]

+ [email protected] "x"

+ [email protected] ")"

+ [email protected] " "

+ [email protected] "="

+ [email protected] " "

+ [email protected]

+ [email protected] "opt"

+ [email protected] " "

+ [email protected]

+ [email protected] "else"

+ [email protected] " "

+ [email protected]

+ [email protected] "{"

+ [email protected] " "

+ [email protected]

+ [email protected] "return"

+ [email protected] " "

+ [email protected] "}"

+ [email protected] ";"

+ [email protected] " "

+ [email protected] "}"

+ [email protected] "\n"

diff --git a/crates/syntax/test_data/parser/inline/ok/0194_let_else.rs b/crates/syntax/test_data/parser/inline/ok/0194_let_else.rs
new file mode 100644
index 0000000000..8303de06f1
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0194_let_else.rs

@@ -0,0 +1 @@

+fn f() { let Some(x) = opt else { return }; }