Repository: rust-analyzer/rust-analyzer
Pull request #5643 (2020-08-01 17:27:26)

Add new consuming modifier, apply consuming and mutable to methods
This adds a new `consuming` semantic modifier for syntax highlighters.

This also emits `mutable` and `consuming` in two cases:

- When a method takes `&mut self`, then it now has `function.mutable` emitted.
- When a method takes `self`, and the type of `Self` is not `Copy`, then `function.consuming` is emitted.

CC @flodiebold 

Nashenas88: This is crashing in some cases... working on a fix now.

Patch:
diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index c442654dd0..31d5276b0f 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -670,6 +670,21 @@ impl Function {
         db.function_data(self.id).has_self_param
     }
 
+    pub fn mutability_of_self_param(self, db: &dyn HirDatabase) -> Option<Mutability> {
+        let func_data = db.function_data(self.id);
+        if !func_data.has_self_param {
+            return None;
+        }
+
+        func_data.params.first().and_then(|param| {
+            if let TypeRef::Reference(_, mutability) = param {
+                Some(*mutability)
+            } else {
+                None
+            }
+        })
+    }
+
     pub fn params(self, db: &dyn HirDatabase) -> Vec<TypeRef> {
         db.function_data(self.id).params.clone()
     }
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 8961ba8fd6..fc1c1ccd3d 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -38,7 +38,7 @@ pub use crate::{
         Static, Struct, Trait, Type, TypeAlias, TypeParam, Union, VariantDef, Visibility,
     },
     has_source::HasSource,
-    semantics::{original_range, PathResolution, Semantics, SemanticsScope},
+    semantics::{original_range, PathResolution, SelfKind, Semantics, SemanticsScope},
 };
 
 pub use hir_def::{
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index c693176fa4..aff0e73da7 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -6,8 +6,10 @@ use std::{cell::RefCell, fmt, iter::successors};
 
 use base_db::{FileId, FileRange};
 use hir_def::{
+    lang_item::LangItemTarget,
     resolver::{self, HasResolver, Resolver, TypeNs},
-    AsMacroCall, FunctionId, TraitId, VariantId,
+    src::HasSource,
+    AsMacroCall, FunctionId, Lookup, TraitId, VariantId,
 };
 use hir_expand::{hygiene::Hygiene, name::AsName, ExpansionInfo};
 use hir_ty::associated_type_shorthand_candidates;
@@ -15,7 +17,7 @@ use itertools::Itertools;
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{
     algo::{find_node_at_offset, skip_trivia_token},
-    ast, AstNode, Direction, SyntaxNode, SyntaxToken, TextRange, TextSize,
+    ast, AstNode, Direction, SmolStr, SyntaxNode, SyntaxToken, TextRange, TextSize,
 };
 
 use crate::{
@@ -79,6 +81,13 @@ impl PathResolution {
     }
 }
 
+pub enum SelfKind {
+    Shared,
+    Mutable,
+    Consuming,
+    Copied,
+}
+
 /// Primary API to get semantic information, like types, from syntax trees.
 pub struct Semantics<'db, DB> {
     pub db: &'db DB,
@@ -188,6 +197,10 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.type_of_self(param)
     }
 
+    pub fn method_reciever_kind(&self, call: &ast::MethodCallExpr) -> Option<SelfKind> {
+        self.imp.method_receiver_kind(call)
+    }
+
     pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
         self.imp.resolve_method_call(call).map(Function::from)
     }
@@ -267,7 +280,7 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.assert_contains_node(node)
     }
 
-    pub fn is_unsafe_method_call(&self, method_call_expr: ast::MethodCallExpr) -> bool {
+    pub fn is_unsafe_method_call(&self, method_call_expr: &ast::MethodCallExpr) -> bool {
         self.imp.is_unsafe_method_call(method_call_expr)
     }
 
@@ -410,6 +423,35 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(param.syntax()).type_of_self(self.db, &param)
     }
 
+    fn method_receiver_kind(&self, call: &ast::MethodCallExpr) -> Option<SelfKind> {
+        self.resolve_method_call(call).and_then(|func| {
+            let lookup = func.lookup(self.db.upcast());
+            let src = lookup.source(self.db.upcast());
+            let param_list = src.value.param_list()?;
+            let self_param = param_list.self_param()?;
+            if self_param.amp_token().is_some() {
+                return Some(if self_param.mut_token().is_some() {
+                    SelfKind::Mutable
+                } else {
+                    SelfKind::Shared
+                });
+            }
+
+            let ty = self.type_of_expr(&call.expr()?)?;
+            let krate = Function::from(func).krate(self.db)?;
+            let lang_item = self.db.lang_item(krate.id, SmolStr::new("copy"));
+            let copy_trait = match lang_item? {
+                LangItemTarget::TraitId(copy_trait) => Trait::from(copy_trait),
+                _ => return None,
+            };
+            Some(if ty.impls_trait(self.db, copy_trait, &[]) {
+                SelfKind::Copied
+            } else {
+                SelfKind::Consuming
+            })
+        })
+    }
+
     fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<FunctionId> {
         self.analyze(call.syntax()).resolve_method_call(self.db, call)
     }
@@ -571,7 +613,7 @@ impl<'db> SemanticsImpl<'db> {
         InFile::new(file_id, node)
     }
 
-    pub fn is_unsafe_method_call(&self, method_call_expr: ast::MethodCallExpr) -> bool {
+    pub fn is_unsafe_method_call(&self, method_call_expr: &ast::MethodCallExpr) -> bool {
         method_call_expr
             .expr()
             .and_then(|expr| {
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
index 5d7c7e8d02..9827c68afb 100644
--- a/crates/ide/src/syntax_highlighting.rs
+++ b/crates/ide/src/syntax_highlighting.rs
@@ -4,7 +4,7 @@ mod injection;
 #[cfg(test)]
 mod tests;
 
-use hir::{Name, Semantics, VariantDef};
+use hir::{Mutability, Name, SelfKind, Semantics, VariantDef};
 use ide_db::{
     defs::{classify_name, classify_name_ref, Definition, NameClass, NameRefClass},
     RootDatabase,
@@ -519,27 +519,29 @@ fn highlight_element(
         }
         NAME_REF => {
             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
-            let possibly_unsafe = is_possibly_unsafe(&name_ref);
-            match classify_name_ref(sema, &name_ref) {
-                Some(name_kind) => match name_kind {
-                    NameRefClass::ExternCrate(_) => HighlightTag::Module.into(),
-                    NameRefClass::Definition(def) => {
-                        if let Definition::Local(local) = &def {
-                            if let Some(name) = local.name(db) {
-                                let shadow_count =
-                                    bindings_shadow_count.entry(name.clone()).or_default();
-                                binding_hash = Some(calc_binding_hash(&name, *shadow_count))
-                            }
-                        };
-                        highlight_name(sema, db, def, Some(name_ref), possibly_unsafe)
+            highlight_func_by_name_ref(sema, &name_ref).unwrap_or_else(|| {
+                let possibly_unsafe = is_possibly_unsafe(&name_ref);
+                match classify_name_ref(sema, &name_ref) {
+                    Some(name_kind) => match name_kind {
+                        NameRefClass::ExternCrate(_) => HighlightTag::Module.into(),
+                        NameRefClass::Definition(def) => {
+                            if let Definition::Local(local) = &def {
+                                if let Some(name) = local.name(db) {
+                                    let shadow_count =
+                                        bindings_shadow_count.entry(name.clone()).or_default();
+                                    binding_hash = Some(calc_binding_hash(&name, *shadow_count))
+                                }
+                            };
+                            highlight_name(sema, db, def, Some(name_ref), possibly_unsafe)
+                        }
+                        NameRefClass::FieldShorthand { .. } => HighlightTag::Field.into(),
+                    },
+                    None if syntactic_name_ref_highlighting => {
+                        highlight_name_ref_by_syntax(name_ref, sema)
                     }
-                    NameRefClass::FieldShorthand { .. } => HighlightTag::Field.into(),
-                },
-                None if syntactic_name_ref_highlighting => {
-                    highlight_name_ref_by_syntax(name_ref, sema)
+                    None => HighlightTag::UnresolvedReference.into(),
                 }
-                None => HighlightTag::UnresolvedReference.into(),
-            }
+            })
         }
 
         // Simple token-based highlighting
@@ -700,6 +702,35 @@ fn is_child_of_impl(element: &SyntaxElement) -> bool {
     }
 }
 
+fn highlight_func_by_name_ref(
+    sema: &Semantics<RootDatabase>,
+    name_ref: &ast::NameRef,
+) -> Option<Highlight> {
+    let parent = name_ref.syntax().parent()?;
+    let method_call = ast::MethodCallExpr::cast(parent)?;
+    highlight_method_call(sema, &method_call)
+}
+
+fn highlight_method_call(
+    sema: &Semantics<RootDatabase>,
+    method_call: &ast::MethodCallExpr,
+) -> Option<Highlight> {
+    let func = sema.resolve_method_call(&method_call)?;
+    let mut h = HighlightTag::Function.into();
+    if func.is_unsafe(sema.db) || sema.is_unsafe_method_call(&method_call) {
+        h |= HighlightModifier::Unsafe;
+    }
+
+    sema.method_reciever_kind(&method_call)
+        .map(|self_kind| match self_kind {
+            SelfKind::Shared => h,
+            SelfKind::Mutable => h | HighlightModifier::Mutable,
+            SelfKind::Consuming => h | HighlightModifier::Consuming,
+            SelfKind::Copied => h,
+        })
+        .or_else(|| Some(h))
+}
+
 fn highlight_name(
     sema: &Semantics<RootDatabase>,
     db: &RootDatabase,
@@ -722,20 +753,26 @@ fn highlight_name(
         Definition::ModuleDef(def) => match def {
             hir::ModuleDef::Module(_) => HighlightTag::Module,
             hir::ModuleDef::Function(func) => {
-                let mut h = HighlightTag::Function.into();
-                if func.is_unsafe(db) {
-                    h |= HighlightModifier::Unsafe;
-                } else {
-                    let is_unsafe = name_ref
-                        .and_then(|name_ref| name_ref.syntax().parent())
-                        .and_then(ast::MethodCallExpr::cast)
-                        .map(|method_call_expr| sema.is_unsafe_method_call(method_call_expr))
-                        .unwrap_or(false);
-                    if is_unsafe {
-                        h |= HighlightModifier::Unsafe;
-                    }
-                }
-                return h;
+                return name_ref
+                    .and_then(|name_ref| highlight_func_by_name_ref(sema, &name_ref))
+                    .unwrap_or_else(|| {
+                        let mut h = HighlightTag::Function.into();
+                        if func.is_unsafe(db) {
+                            h |= HighlightModifier::Unsafe;
+                        }
+
+                        return if func.has_self_param(db) {
+                            match func.mutability_of_self_param(db) {
+                                Some(mutability) => match mutability {
+                                    Mutability::Mut => h | HighlightModifier::Mutable,
+                                    Mutability::Shared => h,
+                                },
+                                None => h,
+                            }
+                        } else {
+                            h
+                        };
+                    });
             }
             hir::ModuleDef::Adt(hir::Adt::Struct(_)) => HighlightTag::Struct,
             hir::ModuleDef::Adt(hir::Adt::Enum(_)) => HighlightTag::Enum,
@@ -807,15 +844,9 @@ fn highlight_name_ref_by_syntax(name: ast::NameRef, sema: &Semantics<RootDatabas
 
     match parent.kind() {
         METHOD_CALL_EXPR => {
-            let mut h = Highlight::new(HighlightTag::Function);
-            let is_unsafe = ast::MethodCallExpr::cast(parent)
-                .map(|method_call_expr| sema.is_unsafe_method_call(method_call_expr))
-                .unwrap_or(false);
-            if is_unsafe {
-                h |= HighlightModifier::Unsafe;
-            }
-
-            h
+            return ast::MethodCallExpr::cast(parent)
+                .and_then(|method_call| highlight_method_call(sema, &method_call))
+                .unwrap_or_else(|| HighlightTag::Function.into());
         }
         FIELD_EXPR => {
             let h = HighlightTag::Field;
diff --git a/crates/ide/src/syntax_highlighting/tags.rs b/crates/ide/src/syntax_highlighting/tags.rs
index 49ec94bdcd..c1b817f06c 100644
--- a/crates/ide/src/syntax_highlighting/tags.rs
+++ b/crates/ide/src/syntax_highlighting/tags.rs
@@ -62,6 +62,7 @@ pub enum HighlightModifier {
     Documentation,
     Injected,
     Mutable,
+    Consuming,
     Unsafe,
 }
 
@@ -119,6 +120,7 @@ impl HighlightModifier {
         HighlightModifier::Documentation,
         HighlightModifier::Injected,
         HighlightModifier::Mutable,
+        HighlightModifier::Consuming,
         HighlightModifier::Unsafe,
     ];
 
@@ -130,6 +132,7 @@ impl HighlightModifier {
             HighlightModifier::Documentation => "documentation",
             HighlightModifier::Injected => "injected",
             HighlightModifier::Mutable => "mutable",
+            HighlightModifier::Consuming => "consuming",
             HighlightModifier::Unsafe => "unsafe",
         }
     }
diff --git a/crates/rust-analyzer/src/semantic_tokens.rs b/crates/rust-analyzer/src/semantic_tokens.rs
index afc38fb4e8..9db7b8af58 100644
--- a/crates/rust-analyzer/src/semantic_tokens.rs
+++ b/crates/rust-analyzer/src/semantic_tokens.rs
@@ -75,6 +75,7 @@ define_semantic_token_modifiers![
     (CONTROL_FLOW, "controlFlow"),
     (INJECTED, "injected"),
     (MUTABLE, "mutable"),
+    (CONSUMING, "consuming"),
     (UNSAFE, "unsafe"),
     (ATTRIBUTE_MODIFIER, "attribute"),
 ];
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 8a2cfa2aee..44c006e4c9 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -400,6 +400,7 @@ fn semantic_token_type_and_modifiers(
             HighlightModifier::Injected => semantic_tokens::INJECTED,
             HighlightModifier::ControlFlow => semantic_tokens::CONTROL_FLOW,
             HighlightModifier::Mutable => semantic_tokens::MUTABLE,
+            HighlightModifier::Consuming => semantic_tokens::CONSUMING,
             HighlightModifier::Unsafe => semantic_tokens::UNSAFE,
         };
         mods |= modifier;


Test patch:
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index 94f37d773f..ccb76f5529 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -12,6 +12,12 @@ fn test_highlighting() {
 use inner::{self as inner_mod};
 mod inner {}
 
+// Needed for function consuming vs normal
+pub mod marker {
+    #[lang = "copy"]
+    pub trait Copy {}
+}
+
 #[derive(Clone, Debug)]
 struct Foo {
     pub x: i32,
@@ -36,6 +42,29 @@ impl Foo {
     fn qux(&mut self) {
         self.x = 0;
     }
+
+    fn quop(&self) -> i32 {
+        self.x
+    }
+}
+
+#[derive(Copy, Clone)]
+struct FooCopy {
+    x: u32,
+}
+
+impl FooCopy {
+    fn baz(self) -> u32 {
+        self.x
+    }
+
+    fn qux(&mut self) {
+        self.x = 0;
+    }
+
+    fn quop(&self) -> u32 {
+        self.x
+    }
 }
 
 static mut STATIC_MUT: i32 = 0;
@@ -87,6 +116,16 @@ fn main() {
     let Foo { x: z, y } = Foo { x: z, y };
 
     y;
+
+    let mut foo = Foo { x, y: x };
+    foo.quop();
+    foo.qux();
+    foo.baz();
+
+    let mut copy = FooCopy { x };
+    copy.quop();
+    copy.qux();
+    copy.baz();
 }
 
 enum Option<T> {
diff --git a/crates/ide/test_data/highlighting.html b/crates/ide/test_data/highlighting.html
index 8e0160eee5..a6b79589bf 100644
--- a/crates/ide/test_data/highlighting.html
+++ b/crates/ide/test_data/highlighting.html
@@ -38,6 +38,12 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 <pre><code><span class="keyword">use</span> <span class="module">inner</span><span class="operator">::</span><span class="punctuation">{</span><span class="self_keyword">self</span> <span class="keyword">as</span> <span class="module declaration">inner_mod</span><span class="punctuation">}</span><span class="punctuation">;</span>
 <span class="keyword">mod</span> <span class="module declaration">inner</span> <span class="punctuation">{</span><span class="punctuation">}</span>
 
+<span class="comment">// Needed for function consuming vs normal</span>
+<span class="keyword">pub</span> <span class="keyword">mod</span> <span class="module declaration">marker</span> <span class="punctuation">{</span>
+    <span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">lang</span><span class="attribute"> </span><span class="operator">=</span><span class="attribute"> </span><span class="string_literal">"copy"</span><span class="attribute">]</span>
+    <span class="keyword">pub</span> <span class="keyword">trait</span> <span class="trait declaration">Copy</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
 <span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Clone</span><span class="punctuation">,</span><span class="attribute"> Debug</span><span class="punctuation">)</span><span class="attribute">]</span>
 <span class="keyword">struct</span> <span class="struct declaration">Foo</span> <span class="punctuation">{</span>
     <span class="keyword">pub</span> <span class="field declaration">x</span><span class="punctuation">:</span> <span class="builtin_type">i32</span><span class="punctuation">,</span>
@@ -59,9 +65,32 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
         <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
     <span class="punctuation">}</span>
 
-    <span class="keyword">fn</span> <span class="function declaration">qux</span><span class="punctuation">(</span><span class="operator">&</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration mutable">qux</span><span class="punctuation">(</span><span class="operator">&</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">)</span> <span class="punctuation">{</span>
         <span class="self_keyword mutable">self</span><span class="punctuation">.</span><span class="field">x</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
     <span class="punctuation">}</span>
+
+    <span class="keyword">fn</span> <span class="function declaration">quop</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">i32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Copy</span><span class="punctuation">,</span><span class="attribute"> Clone</span><span class="punctuation">)</span><span class="attribute">]</span>
+<span class="keyword">struct</span> <span class="struct declaration">FooCopy</span> <span class="punctuation">{</span>
+    <span class="field declaration">x</span><span class="punctuation">:</span> <span class="builtin_type">u32</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="struct">FooCopy</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">(</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">u32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
+
+    <span class="keyword">fn</span> <span class="function declaration mutable">qux</span><span class="punctuation">(</span><span class="operator">&</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+        <span class="self_keyword mutable">self</span><span class="punctuation">.</span><span class="field">x</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
+    <span class="punctuation">}</span>
+
+    <span class="keyword">fn</span> <span class="function declaration">quop</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">u32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
 <span class="punctuation">}</span>
 
 <span class="keyword">static</span> <span class="keyword">mut</span> <span class="static declaration mutable unsafe">STATIC_MUT</span><span class="punctuation">:</span> <span class="builtin_type">i32</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
@@ -113,6 +142,16 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="keyword">let</span> <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">x</span><span class="punctuation">:</span> <span class="variable declaration">z</span><span class="punctuation">,</span> <span class="field">y</span> <span class="punctuation">}</span> <span class="operator">=</span> <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">x</span><span class="punctuation">:</span> <span class="variable">z</span><span class="punctuation">,</span> <span class="field">y</span> <span class="punctuation">}</span><span class="punctuation">;</span>
 
     <span class="variable">y</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">foo</span> <span class="operator">=</span> <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">x</span><span class="punctuation">,</span> <span class="field">y</span><span class="punctuation">:</span> <span class="variable mutable">x</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+    <span class="variable mutable">foo</span><span class="punctuation">.</span><span class="function">quop</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">foo</span><span class="punctuation">.</span><span class="function mutable">qux</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">foo</span><span class="punctuation">.</span><span class="function consuming">baz</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">copy</span> <span class="operator">=</span> <span class="struct">FooCopy</span> <span class="punctuation">{</span> <span class="field">x</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+    <span class="variable mutable">copy</span><span class="punctuation">.</span><span class="function">quop</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">copy</span><span class="punctuation">.</span><span class="function mutable">qux</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">copy</span><span class="punctuation">.</span><span class="function">baz</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
 <span class="punctuation">}</span>
 
 <span class="keyword">enum</span> <span class="enum declaration">Option</span><span class="punctuation">&lt;</span><span class="type_param declaration">T</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span>