Merge branch 'master' of github.com:rust-analyzer/rust-analyzer into fix_4202

11 files changed, 533 insertions, 67 deletions

diff --git a/crates/ra_ide/src/completion/complete_dot.rs b/crates/ra_ide/src/completion/complete_dot.rs
index 814354ffa..05f825c6f 100644
--- a/crates/ra_ide/src/completion/complete_dot.rs
+++ b/crates/ra_ide/src/completion/complete_dot.rs
@@ -250,6 +250,44 @@ mod tests {
     }
 
     #[test]
+    fn test_union_field_completion() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+            union Un {
+                field: u8,
+                other: u16,
+            }
+
+            fn foo(u: Un) {
+                u.<|>
+            }
+            ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "field",
+                source_range: 140..140,
+                delete: 140..140,
+                insert: "field",
+                kind: Field,
+                detail: "u8",
+            },
+            CompletionItem {
+                label: "other",
+                source_range: 140..140,
+                delete: 140..140,
+                insert: "other",
+                kind: Field,
+                detail: "u16",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
     fn test_method_completion() {
         assert_debug_snapshot!(
         do_ref_completion(
diff --git a/crates/ra_ide/src/completion/complete_qualified_path.rs b/crates/ra_ide/src/completion/complete_qualified_path.rs
index dd10f74e6..aa56a5cd8 100644
--- a/crates/ra_ide/src/completion/complete_qualified_path.rs
+++ b/crates/ra_ide/src/completion/complete_qualified_path.rs
@@ -5,19 +5,29 @@ use ra_syntax::AstNode;
 use test_utils::tested_by;
 
 use crate::completion::{CompletionContext, Completions};
+use rustc_hash::FxHashSet;
 
 pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionContext) {
     let path = match &ctx.path_prefix {
         Some(path) => path.clone(),
         _ => return,
     };
-    let def = match ctx.scope().resolve_hir_path(&path) {
-        Some(PathResolution::Def(def)) => def,
-        _ => return,
+    let scope = ctx.scope();
+    let context_module = scope.module();
+
+    let res = match scope.resolve_hir_path(&path) {
+        Some(res) => res,
+        None => return,
     };
-    let context_module = ctx.scope().module();
-    match def {
-        hir::ModuleDef::Module(module) => {
+
+    // Add associated types on type parameters and `Self`.
+    res.assoc_type_shorthand_candidates(ctx.db, |alias| {
+        acc.add_type_alias(ctx, alias);
+        None::<()>
+    });
+
+    match res {
+        PathResolution::Def(hir::ModuleDef::Module(module)) => {
             let module_scope = module.scope(ctx.db, context_module);
             for (name, def) in module_scope {
                 if ctx.use_item_syntax.is_some() {
@@ -35,7 +45,8 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 acc.add_resolution(ctx, name.to_string(), &def);
             }
         }
-        hir::ModuleDef::Adt(_) | hir::ModuleDef::TypeAlias(_) => {
+        PathResolution::Def(def @ hir::ModuleDef::Adt(_))
+        | PathResolution::Def(def @ hir::ModuleDef::TypeAlias(_)) => {
             if let hir::ModuleDef::Adt(Adt::Enum(e)) = def {
                 for variant in e.variants(ctx.db) {
                     acc.add_enum_variant(ctx, variant, None);
@@ -46,8 +57,10 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
                 _ => unreachable!(),
             };
-            // Iterate assoc types separately
-            // FIXME: complete T::AssocType
+
+            // XXX: For parity with Rust bug #22519, this does not complete Ty::AssocType.
+            // (where AssocType is defined on a trait, not an inherent impl)
+
             let krate = ctx.krate;
             if let Some(krate) = krate {
                 let traits_in_scope = ctx.scope().traits_in_scope();
@@ -65,6 +78,7 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                     None::<()>
                 });
 
+                // Iterate assoc types separately
                 ty.iterate_impl_items(ctx.db, krate, |item| {
                     if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
                         return None;
@@ -77,7 +91,8 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 });
             }
         }
-        hir::ModuleDef::Trait(t) => {
+        PathResolution::Def(hir::ModuleDef::Trait(t)) => {
+            // Handles `Trait::assoc` as well as `<Ty as Trait>::assoc`.
             for item in t.items(ctx.db) {
                 if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
                     continue;
@@ -91,8 +106,38 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 }
             }
         }
+        PathResolution::TypeParam(_) | PathResolution::SelfType(_) => {
+            if let Some(krate) = ctx.krate {
+                let ty = match res {
+                    PathResolution::TypeParam(param) => param.ty(ctx.db),
+                    PathResolution::SelfType(impl_def) => impl_def.target_ty(ctx.db),
+                    _ => return,
+                };
+
+                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| {
+                    if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
+                        return None;
+                    }
+
+                    // We might iterate candidates of a trait multiple times here, so deduplicate
+                    // them.
+                    if seen.insert(item) {
+                        match item {
+                            hir::AssocItem::Function(func) => {
+                                acc.add_function(ctx, func, None);
+                            }
+                            hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
+                            hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
+                        }
+                    }
+                    None::<()>
+                });
+            }
+        }
         _ => {}
-    };
+    }
 }
 
 #[cfg(test)]
@@ -844,6 +889,211 @@ mod tests {
     }
 
     #[test]
+    fn completes_ty_param_assoc_ty() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /lib.rs
+                trait Super {
+                    type Ty;
+                    const CONST: u8;
+                    fn func() {}
+                    fn method(&self) {}
+                }
+
+                trait Sub: Super {
+                    type SubTy;
+                    const C2: ();
+                    fn subfunc() {}
+                    fn submethod(&self) {}
+                }
+
+                fn foo<T: Sub>() {
+                    T::<|>
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "C2",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "C2",
+                kind: Const,
+                detail: "const C2: ();",
+            },
+            CompletionItem {
+                label: "CONST",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "CONST",
+                kind: Const,
+                detail: "const CONST: u8;",
+            },
+            CompletionItem {
+                label: "SubTy",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "SubTy",
+                kind: TypeAlias,
+                detail: "type SubTy;",
+            },
+            CompletionItem {
+                label: "Ty",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "Ty",
+                kind: TypeAlias,
+                detail: "type Ty;",
+            },
+            CompletionItem {
+                label: "func()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "func()$0",
+                kind: Function,
+                lookup: "func",
+                detail: "fn func()",
+            },
+            CompletionItem {
+                label: "method()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "method()$0",
+                kind: Method,
+                lookup: "method",
+                detail: "fn method(&self)",
+            },
+            CompletionItem {
+                label: "subfunc()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "subfunc()$0",
+                kind: Function,
+                lookup: "subfunc",
+                detail: "fn subfunc()",
+            },
+            CompletionItem {
+                label: "submethod()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "submethod()$0",
+                kind: Method,
+                lookup: "submethod",
+                detail: "fn submethod(&self)",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn completes_self_param_assoc_ty() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /lib.rs
+                trait Super {
+                    type Ty;
+                    const CONST: u8 = 0;
+                    fn func() {}
+                    fn method(&self) {}
+                }
+
+                trait Sub: Super {
+                    type SubTy;
+                    const C2: () = ();
+                    fn subfunc() {}
+                    fn submethod(&self) {}
+                }
+
+                struct Wrap<T>(T);
+                impl<T> Super for Wrap<T> {}
+                impl<T> Sub for Wrap<T> {
+                    fn subfunc() {
+                        // Should be able to assume `Self: Sub + Super`
+                        Self::<|>
+                    }
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "C2",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "C2",
+                kind: Const,
+                detail: "const C2: () = ();",
+            },
+            CompletionItem {
+                label: "CONST",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "CONST",
+                kind: Const,
+                detail: "const CONST: u8 = 0;",
+            },
+            CompletionItem {
+                label: "SubTy",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "SubTy",
+                kind: TypeAlias,
+                detail: "type SubTy;",
+            },
+            CompletionItem {
+                label: "Ty",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "Ty",
+                kind: TypeAlias,
+                detail: "type Ty;",
+            },
+            CompletionItem {
+                label: "func()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "func()$0",
+                kind: Function,
+                lookup: "func",
+                detail: "fn func()",
+            },
+            CompletionItem {
+                label: "method()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "method()$0",
+                kind: Method,
+                lookup: "method",
+                detail: "fn method(&self)",
+            },
+            CompletionItem {
+                label: "subfunc()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "subfunc()$0",
+                kind: Function,
+                lookup: "subfunc",
+                detail: "fn subfunc()",
+            },
+            CompletionItem {
+                label: "submethod()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "submethod()$0",
+                kind: Method,
+                lookup: "submethod",
+                detail: "fn submethod(&self)",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
     fn completes_type_alias() {
         assert_debug_snapshot!(
             do_reference_completion(
diff --git a/crates/ra_ide/src/completion/complete_unqualified_path.rs b/crates/ra_ide/src/completion/complete_unqualified_path.rs
index f559f2b97..a6a5568de 100644
--- a/crates/ra_ide/src/completion/complete_unqualified_path.rs
+++ b/crates/ra_ide/src/completion/complete_unqualified_path.rs
@@ -53,7 +53,7 @@ fn complete_enum_variants(acc: &mut Completions, ctx: &CompletionContext, ty: &T
                 // Variants with trivial paths are already added by the existing completion logic,
                 // so we should avoid adding these twice
                 if path.segments.len() > 1 {
-                    acc.add_enum_variant(ctx, variant, Some(path.to_string()));
+                    acc.add_qualified_enum_variant(ctx, variant, path);
                 }
             }
         }
@@ -1173,6 +1173,7 @@ mod tests {
                 delete: 248..250,
                 insert: "Foo::Bar",
                 kind: EnumVariant,
+                lookup: "Bar",
                 detail: "()",
             },
             CompletionItem {
@@ -1181,6 +1182,7 @@ mod tests {
                 delete: 248..250,
                 insert: "Foo::Baz",
                 kind: EnumVariant,
+                lookup: "Baz",
                 detail: "()",
             },
             CompletionItem {
@@ -1189,6 +1191,7 @@ mod tests {
                 delete: 248..250,
                 insert: "Foo::Quux",
                 kind: EnumVariant,
+                lookup: "Quux",
                 detail: "()",
             },
         ]
@@ -1231,6 +1234,7 @@ mod tests {
                 delete: 219..221,
                 insert: "Foo::Bar",
                 kind: EnumVariant,
+                lookup: "Bar",
                 detail: "()",
             },
             CompletionItem {
@@ -1239,6 +1243,7 @@ mod tests {
                 delete: 219..221,
                 insert: "Foo::Baz",
                 kind: EnumVariant,
+                lookup: "Baz",
                 detail: "()",
             },
             CompletionItem {
@@ -1247,6 +1252,7 @@ mod tests {
                 delete: 219..221,
                 insert: "Foo::Quux",
                 kind: EnumVariant,
+                lookup: "Quux",
                 detail: "()",
             },
         ]
@@ -1285,6 +1291,7 @@ mod tests {
                 delete: 185..186,
                 insert: "Foo::Bar",
                 kind: EnumVariant,
+                lookup: "Bar",
                 detail: "()",
             },
             CompletionItem {
@@ -1293,6 +1300,7 @@ mod tests {
                 delete: 185..186,
                 insert: "Foo::Baz",
                 kind: EnumVariant,
+                lookup: "Baz",
                 detail: "()",
             },
             CompletionItem {
@@ -1301,6 +1309,7 @@ mod tests {
                 delete: 185..186,
                 insert: "Foo::Quux",
                 kind: EnumVariant,
+                lookup: "Quux",
                 detail: "()",
             },
             CompletionItem {
@@ -1353,6 +1362,7 @@ mod tests {
                 delete: 98..99,
                 insert: "m::E::V",
                 kind: EnumVariant,
+                lookup: "V",
                 detail: "()",
             },
         ]
diff --git a/crates/ra_ide/src/completion/completion_context.rs b/crates/ra_ide/src/completion/completion_context.rs
index 118fceb2e..c529752d4 100644
--- a/crates/ra_ide/src/completion/completion_context.rs
+++ b/crates/ra_ide/src/completion/completion_context.rs
@@ -344,7 +344,7 @@ impl<'a> CompletionContext<'a> {
                                 stmt.syntax().text_range() == name_ref.syntax().text_range(),
                             );
                         }
-                        if let Some(block) = ast::Block::cast(node) {
+                        if let Some(block) = ast::BlockExpr::cast(node) {
                             return Some(
                                 block.expr().map(|e| e.syntax().text_range())
                                     == Some(name_ref.syntax().text_range()),
diff --git a/crates/ra_ide/src/completion/presentation.rs b/crates/ra_ide/src/completion/presentation.rs
index 77d354376..2edb130cf 100644
--- a/crates/ra_ide/src/completion/presentation.rs
+++ b/crates/ra_ide/src/completion/presentation.rs
@@ -1,6 +1,6 @@
 //! This modules takes care of rendering various definitions as completion items.
 
-use hir::{Docs, HasAttrs, HasSource, HirDisplay, ScopeDef, StructKind, Type};
+use hir::{Docs, HasAttrs, HasSource, HirDisplay, ModPath, ScopeDef, StructKind, Type};
 use ra_syntax::ast::NameOwner;
 use stdx::SepBy;
 use test_utils::tested_by;
@@ -246,14 +246,37 @@ impl Completions {
             .add_to(self);
     }
 
+    pub(crate) fn add_qualified_enum_variant(
+        &mut self,
+        ctx: &CompletionContext,
+        variant: hir::EnumVariant,
+        path: ModPath,
+    ) {
+        self.add_enum_variant_impl(ctx, variant, None, Some(path))
+    }
+
     pub(crate) fn add_enum_variant(
         &mut self,
         ctx: &CompletionContext,
         variant: hir::EnumVariant,
         local_name: Option<String>,
     ) {
+        self.add_enum_variant_impl(ctx, variant, local_name, None)
+    }
+
+    fn add_enum_variant_impl(
+        &mut self,
+        ctx: &CompletionContext,
+        variant: hir::EnumVariant,
+        local_name: Option<String>,
+        path: Option<ModPath>,
+    ) {
         let is_deprecated = is_deprecated(variant, ctx.db);
         let name = local_name.unwrap_or_else(|| variant.name(ctx.db).to_string());
+        let qualified_name = match &path {
+            Some(it) => it.to_string(),
+            None => name.to_string(),
+        };
         let detail_types = variant
             .fields(ctx.db)
             .into_iter()
@@ -271,16 +294,23 @@ impl Completions {
                 .surround_with("{ ", " }")
                 .to_string(),
         };
-        let mut res =
-            CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.clone())
-                .kind(CompletionItemKind::EnumVariant)
-                .set_documentation(variant.docs(ctx.db))
-                .set_deprecated(is_deprecated)
-                .detail(detail);
+        let mut res = CompletionItem::new(
+            CompletionKind::Reference,
+            ctx.source_range(),
+            qualified_name.clone(),
+        )
+        .kind(CompletionItemKind::EnumVariant)
+        .set_documentation(variant.docs(ctx.db))
+        .set_deprecated(is_deprecated)
+        .detail(detail);
+
+        if path.is_some() {
+            res = res.lookup_by(name);
+        }
 
         if variant_kind == StructKind::Tuple {
             let params = Params::Anonymous(variant.fields(ctx.db).len());
-            res = res.add_call_parens(ctx, name, params)
+            res = res.add_call_parens(ctx, qualified_name, params)
         }
 
         res.add_to(self);
diff --git a/crates/ra_ide/src/display/function_signature.rs b/crates/ra_ide/src/display/function_signature.rs
index b5e2785fe..db3907fe6 100644
--- a/crates/ra_ide/src/display/function_signature.rs
+++ b/crates/ra_ide/src/display/function_signature.rs
@@ -26,6 +26,8 @@ pub struct FunctionSignature {
     pub kind: CallableKind,
     /// Optional visibility
     pub visibility: Option<String>,
+    /// Qualifiers like `async`, `unsafe`, ...
+    pub qualifier: FunctionQualifier,
     /// Name of the function
     pub name: Option<String>,
     /// Documentation for the function
@@ -46,6 +48,16 @@ pub struct FunctionSignature {
     pub has_self_param: bool,
 }
 
+#[derive(Debug, Default)]
+pub struct FunctionQualifier {
+    // `async` and `const` are mutually exclusive. Do we need to enforcing it here?
+    pub is_async: bool,
+    pub is_const: bool,
+    pub is_unsafe: bool,
+    /// The string `extern ".."`
+    pub extern_abi: Option<String>,
+}
+
 impl FunctionSignature {
     pub(crate) fn with_doc_opt(mut self, doc: Option<Documentation>) -> Self {
         self.doc = doc;
@@ -83,6 +95,8 @@ impl FunctionSignature {
             FunctionSignature {
                 kind: CallableKind::StructConstructor,
                 visibility: node.visibility().map(|n| n.syntax().text().to_string()),
+                // Do we need `const`?
+                qualifier: Default::default(),
                 name: node.name().map(|n| n.text().to_string()),
                 ret_type: node.name().map(|n| n.text().to_string()),
                 parameters: params,
@@ -128,6 +142,8 @@ impl FunctionSignature {
             FunctionSignature {
                 kind: CallableKind::VariantConstructor,
                 visibility: None,
+                // Do we need `const`?
+                qualifier: Default::default(),
                 name: Some(name),
                 ret_type: None,
                 parameters: params,
@@ -151,6 +167,7 @@ impl FunctionSignature {
             FunctionSignature {
                 kind: CallableKind::Macro,
                 visibility: None,
+                qualifier: Default::default(),
                 name: node.name().map(|n| n.text().to_string()),
                 ret_type: None,
                 parameters: params,
@@ -223,6 +240,12 @@ impl From<&'_ ast::FnDef> for FunctionSignature {
         FunctionSignature {
             kind: CallableKind::Function,
             visibility: node.visibility().map(|n| n.syntax().text().to_string()),
+            qualifier: FunctionQualifier {
+                is_async: node.async_token().is_some(),
+                is_const: node.const_token().is_some(),
+                is_unsafe: node.unsafe_token().is_some(),
+                extern_abi: node.abi().map(|n| n.to_string()),
+            },
             name: node.name().map(|n| n.text().to_string()),
             ret_type: node
                 .ret_type()
@@ -246,6 +269,23 @@ impl Display for FunctionSignature {
             write!(f, "{} ", t)?;
         }
 
+        if self.qualifier.is_async {
+            write!(f, "async ")?;
+        }
+
+        if self.qualifier.is_const {
+            write!(f, "const ")?;
+        }
+
+        if self.qualifier.is_unsafe {
+            write!(f, "unsafe ")?;
+        }
+
+        if let Some(extern_abi) = &self.qualifier.extern_abi {
+            // Keyword `extern` is included in the string.
+            write!(f, "{} ", extern_abi)?;
+        }
+
         if let Some(name) = &self.name {
             match self.kind {
                 CallableKind::Function => write!(f, "fn {}", name)?,
diff --git a/crates/ra_ide/src/display/short_label.rs b/crates/ra_ide/src/display/short_label.rs
index 4b081bf6c..d37260e96 100644
--- a/crates/ra_ide/src/display/short_label.rs
+++ b/crates/ra_ide/src/display/short_label.rs
@@ -33,7 +33,11 @@ impl ShortLabel for ast::EnumDef {
 
 impl ShortLabel for ast::TraitDef {
     fn short_label(&self) -> Option<String> {
-        short_label_from_node(self, "trait ")
+        if self.unsafe_token().is_some() {
+            short_label_from_node(self, "unsafe trait ")
+        } else {
+            short_label_from_node(self, "trait ")
+        }
     }
 }
 
diff --git a/crates/ra_ide/src/folding_ranges.rs b/crates/ra_ide/src/folding_ranges.rs
index 4379005aa..8657377de 100644
--- a/crates/ra_ide/src/folding_ranges.rs
+++ b/crates/ra_ide/src/folding_ranges.rs
@@ -88,7 +88,7 @@ fn fold_kind(kind: SyntaxKind) -> Option<FoldKind> {
         | ITEM_LIST
         | EXTERN_ITEM_LIST
         | USE_TREE_LIST
-        | BLOCK
+        | BLOCK_EXPR
         | MATCH_ARM_LIST
         | ENUM_VARIANT_LIST
         | TOKEN_TREE => Some(FoldKind::Block),
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index 58c799eca..54d318858 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -844,4 +844,40 @@ fn func(foo: i32) { if true { <|>foo; }; }
             &["fn foo()\n```\n\n<- `\u{3000}` here"],
         );
     }
+
+    #[test]
+    fn test_hover_function_show_qualifiers() {
+        check_hover_result(
+            "
+            //- /lib.rs
+            async fn foo<|>() {}
+            ",
+            &["async fn foo()"],
+        );
+        check_hover_result(
+            "
+            //- /lib.rs
+            pub const unsafe fn foo<|>() {}
+            ",
+            &["pub const unsafe fn foo()"],
+        );
+        check_hover_result(
+            r#"
+            //- /lib.rs
+            pub(crate) async unsafe extern "C" fn foo<|>() {}
+            "#,
+            &[r#"pub(crate) async unsafe extern "C" fn foo()"#],
+        );
+    }
+
+    #[test]
+    fn test_hover_trait_show_qualifiers() {
+        check_hover_result(
+            "
+            //- /lib.rs
+            unsafe trait foo<|>() {}
+            ",
+            &["unsafe trait foo"],
+        );
+    }
 }
diff --git a/crates/ra_ide/src/join_lines.rs b/crates/ra_ide/src/join_lines.rs
index fde0bfa98..63fd6b3e4 100644
--- a/crates/ra_ide/src/join_lines.rs
+++ b/crates/ra_ide/src/join_lines.rs
@@ -129,8 +129,10 @@ fn has_comma_after(node: &SyntaxNode) -> bool {
 }
 
 fn join_single_expr_block(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
-    let block = ast::Block::cast(token.parent())?;
-    let block_expr = ast::BlockExpr::cast(block.syntax().parent()?)?;
+    let block_expr = ast::BlockExpr::cast(token.parent())?;
+    if !block_expr.is_standalone() {
+        return None;
+    }
     let expr = extract_trivial_expression(&block_expr)?;
 
     let block_range = block_expr.syntax().text_range();
@@ -662,4 +664,67 @@ fn main() {
         ",
         )
     }
+
+    #[test]
+    fn join_lines_mandatory_blocks_block() {
+        check_join_lines(
+            r"
+<|>fn foo() {
+    92
+}
+        ",
+            r"
+<|>fn foo() { 92
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>if true {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>if true { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>loop {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>loop { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>unsafe {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>unsafe { 92
+    }
+}
+        ",
+        );
+    }
 }
diff --git a/crates/ra_ide/src/syntax_tree.rs b/crates/ra_ide/src/syntax_tree.rs
index bf97f8c56..86c70ff83 100644
--- a/crates/ra_ide/src/syntax_tree.rs
+++ b/crates/ra_ide/src/syntax_tree.rs
@@ -120,9 +120,8 @@ [email protected]
       [email protected] ")"
     [email protected] " "
     [email protected]
-      [email protected]
-        [email protected] "{"
-        [email protected] "}"
+      [email protected] "{"
+      [email protected] "}"
 "#
             .trim()
         );
@@ -153,26 +152,25 @@ [email protected]
       [email protected] ")"
     [email protected] " "
     [email protected]
-      [email protected]
-        [email protected] "{"
-        [email protected] "\n    "
-        [email protected]
-          [email protected]
-            [email protected]
-              [email protected]
-                [email protected]
-                  [email protected] "assert"
-            [email protected] "!"
-            [email protected]
-              [email protected] "("
-              [email protected] "\"\n    fn foo() {\n     ..."
-              [email protected] ","
-              [email protected] " "
-              [email protected] "\"\""
-              [email protected] ")"
-          [email protected] ";"
-        [email protected] "\n"
-        [email protected] "}"
+      [email protected] "{"
+      [email protected] "\n    "
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected] "assert"
+          [email protected] "!"
+          [email protected]
+            [email protected] "("
+            [email protected] "\"\n    fn foo() {\n     ..."
+            [email protected] ","
+            [email protected] " "
+            [email protected] "\"\""
+            [email protected] ")"
+        [email protected] ";"
+      [email protected] "\n"
+      [email protected] "}"
 "#
             .trim()
         );
@@ -196,9 +194,8 @@ [email protected]
     [email protected] ")"
   [email protected] " "
   [email protected]
-    [email protected]
-      [email protected] "{"
-      [email protected] "}"
+    [email protected] "{"
+    [email protected] "}"
 "#
             .trim()
         );
@@ -265,10 +262,9 @@ [email protected]
       [email protected] ")"
     [email protected] " "
     [email protected]
-      [email protected]
-        [email protected] "{"
-        [email protected] "\n"
-        [email protected] "}"
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
 "#
             .trim()
         );
@@ -300,10 +296,9 @@ [email protected]
       [email protected] ")"
     [email protected] " "
     [email protected]
-      [email protected]
-        [email protected] "{"
-        [email protected] "\n"
-        [email protected] "}"
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
 "#
             .trim()
         );
@@ -334,10 +329,9 @@ [email protected]
       [email protected] ")"
     [email protected] " "
     [email protected]
-      [email protected]
-        [email protected] "{"
-        [email protected] "\n"
-        [email protected] "}"
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
   [email protected] "\n"
   [email protected]
     [email protected] "fn"
@@ -349,10 +343,9 @@ [email protected]
       [email protected] ")"
     [email protected] " "
     [email protected]
-      [email protected]
-        [email protected] "{"
-        [email protected] "\n"
-        [email protected] "}"
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
 "#
             .trim()
         );