10 files changed, 405 insertions, 25 deletions

diff --git a/crates/ide/src/completion.rs b/crates/ide/src/completion.rs
index 33bed6991..daea2aa95 100644
--- a/crates/ide/src/completion.rs
+++ b/crates/ide/src/completion.rs
@@ -19,6 +19,7 @@ mod complete_unqualified_path;
 mod complete_postfix;
 mod complete_macro_in_item_position;
 mod complete_trait_impl;
+mod complete_mod;
 
 use ide_db::RootDatabase;
 
@@ -124,6 +125,7 @@ pub(crate) fn completions(
     complete_postfix::complete_postfix(&mut acc, &ctx);
     complete_macro_in_item_position::complete_macro_in_item_position(&mut acc, &ctx);
     complete_trait_impl::complete_trait_impl(&mut acc, &ctx);
+    complete_mod::complete_mod(&mut acc, &ctx);
 
     Some(acc)
 }
diff --git a/crates/ide/src/completion/complete_attribute.rs b/crates/ide/src/completion/complete_attribute.rs
index 0abfaebcb..f4a9864d1 100644
--- a/crates/ide/src/completion/complete_attribute.rs
+++ b/crates/ide/src/completion/complete_attribute.rs
@@ -13,6 +13,10 @@ use crate::completion::{
 };
 
 pub(super) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
+    if ctx.mod_declaration_under_caret.is_some() {
+        return None;
+    }
+
     let attribute = ctx.attribute_under_caret.as_ref()?;
     match (attribute.path(), attribute.token_tree()) {
         (Some(path), Some(token_tree)) if path.to_string() == "derive" => {
diff --git a/crates/ide/src/completion/complete_mod.rs b/crates/ide/src/completion/complete_mod.rs
new file mode 100644
index 000000000..3cfc2e131
--- /dev/null
+++ b/crates/ide/src/completion/complete_mod.rs
@@ -0,0 +1,324 @@
+//! Completes mod declarations.
+
+use base_db::{SourceDatabaseExt, VfsPath};
+use hir::{Module, ModuleSource};
+use ide_db::RootDatabase;
+use rustc_hash::FxHashSet;
+
+use crate::{CompletionItem, CompletionItemKind};
+
+use super::{
+    completion_context::CompletionContext, completion_item::CompletionKind,
+    completion_item::Completions,
+};
+
+/// Complete mod declaration, i.e. `mod <|> ;`
+pub(super) fn complete_mod(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
+    let mod_under_caret = match &ctx.mod_declaration_under_caret {
+        Some(mod_under_caret) if mod_under_caret.item_list().is_some() => return None,
+        Some(mod_under_caret) => mod_under_caret,
+        None => return None,
+    };
+
+    let _p = profile::span("completion::complete_mod");
+
+    let current_module = ctx.scope.module()?;
+
+    let module_definition_file =
+        current_module.definition_source(ctx.db).file_id.original_file(ctx.db);
+    let source_root = ctx.db.source_root(ctx.db.file_source_root(module_definition_file));
+    let directory_to_look_for_submodules = directory_to_look_for_submodules(
+        current_module,
+        ctx.db,
+        source_root.path_for_file(&module_definition_file)?,
+    )?;
+
+    let existing_mod_declarations = current_module
+        .children(ctx.db)
+        .filter_map(|module| Some(module.name(ctx.db)?.to_string()))
+        .collect::<FxHashSet<_>>();
+
+    let module_declaration_file =
+        current_module.declaration_source(ctx.db).map(|module_declaration_source_file| {
+            module_declaration_source_file.file_id.original_file(ctx.db)
+        });
+
+    source_root
+        .iter()
+        .filter(|submodule_candidate_file| submodule_candidate_file != &module_definition_file)
+        .filter(|submodule_candidate_file| {
+            Some(submodule_candidate_file) != module_declaration_file.as_ref()
+        })
+        .filter_map(|submodule_file| {
+            let submodule_path = source_root.path_for_file(&submodule_file)?;
+            let directory_with_submodule = submodule_path.parent()?;
+            match submodule_path.name_and_extension()? {
+                ("lib", Some("rs")) | ("main", Some("rs")) => None,
+                ("mod", Some("rs")) => {
+                    if directory_with_submodule.parent()? == directory_to_look_for_submodules {
+                        match directory_with_submodule.name_and_extension()? {
+                            (directory_name, None) => Some(directory_name.to_owned()),
+                            _ => None,
+                        }
+                    } else {
+                        None
+                    }
+                }
+                (file_name, Some("rs"))
+                    if directory_with_submodule == directory_to_look_for_submodules =>
+                {
+                    Some(file_name.to_owned())
+                }
+                _ => None,
+            }
+        })
+        .filter(|name| !existing_mod_declarations.contains(name))
+        .for_each(|submodule_name| {
+            let mut label = submodule_name;
+            if mod_under_caret.semicolon_token().is_none() {
+                label.push(';')
+            }
+            acc.add(
+                CompletionItem::new(CompletionKind::Magic, ctx.source_range(), &label)
+                    .kind(CompletionItemKind::Module),
+            )
+        });
+
+    Some(())
+}
+
+fn directory_to_look_for_submodules(
+    module: Module,
+    db: &RootDatabase,
+    module_file_path: &VfsPath,
+) -> Option<VfsPath> {
+    let directory_with_module_path = module_file_path.parent()?;
+    let base_directory = match module_file_path.name_and_extension()? {
+        ("mod", Some("rs")) | ("lib", Some("rs")) | ("main", Some("rs")) => {
+            Some(directory_with_module_path)
+        }
+        (regular_rust_file_name, Some("rs")) => {
+            if matches!(
+                (
+                    directory_with_module_path
+                        .parent()
+                        .as_ref()
+                        .and_then(|path| path.name_and_extension()),
+                    directory_with_module_path.name_and_extension(),
+                ),
+                (Some(("src", None)), Some(("bin", None)))
+            ) {
+                // files in /src/bin/ can import each other directly
+                Some(directory_with_module_path)
+            } else {
+                directory_with_module_path.join(regular_rust_file_name)
+            }
+        }
+        _ => None,
+    }?;
+
+    let mut resulting_path = base_directory;
+    for module in module_chain_to_containing_module_file(module, db) {
+        if let Some(name) = module.name(db) {
+            resulting_path = resulting_path.join(&name.to_string())?;
+        }
+    }
+
+    Some(resulting_path)
+}
+
+fn module_chain_to_containing_module_file(
+    current_module: Module,
+    db: &RootDatabase,
+) -> Vec<Module> {
+    let mut path = Vec::new();
+
+    let mut current_module = Some(current_module);
+    while let Some(ModuleSource::Module(_)) =
+        current_module.map(|module| module.definition_source(db).value)
+    {
+        if let Some(module) = current_module {
+            path.insert(0, module);
+            current_module = module.parent(db);
+        } else {
+            current_module = None;
+        }
+    }
+
+    path
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use expect_test::{expect, Expect};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Magic);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn lib_module_completion() {
+        check(
+            r#"
+            //- /lib.rs
+            mod <|>
+            //- /foo.rs
+            fn foo() {}
+            //- /foo/ignored_foo.rs
+            fn ignored_foo() {}
+            //- /bar/mod.rs
+            fn bar() {}
+            //- /bar/ignored_bar.rs
+            fn ignored_bar() {}
+        "#,
+            expect![[r#"
+                md bar;
+                md foo;
+            "#]],
+        );
+    }
+
+    #[test]
+    fn no_module_completion_with_module_body() {
+        check(
+            r#"
+            //- /lib.rs
+            mod <|> {
+
+            }
+            //- /foo.rs
+            fn foo() {}
+        "#,
+            expect![[r#""#]],
+        );
+    }
+
+    #[test]
+    fn main_module_completion() {
+        check(
+            r#"
+            //- /main.rs
+            mod <|>
+            //- /foo.rs
+            fn foo() {}
+            //- /foo/ignored_foo.rs
+            fn ignored_foo() {}
+            //- /bar/mod.rs
+            fn bar() {}
+            //- /bar/ignored_bar.rs
+            fn ignored_bar() {}
+        "#,
+            expect![[r#"
+                md bar;
+                md foo;
+            "#]],
+        );
+    }
+
+    #[test]
+    fn main_test_module_completion() {
+        check(
+            r#"
+            //- /main.rs
+            mod tests {
+                mod <|>;
+            }
+            //- /tests/foo.rs
+            fn foo() {}
+        "#,
+            expect![[r#"
+                md foo
+            "#]],
+        );
+    }
+
+    #[test]
+    fn directly_nested_module_completion() {
+        check(
+            r#"
+            //- /lib.rs
+            mod foo;
+            //- /foo.rs
+            mod <|>;
+            //- /foo/bar.rs
+            fn bar() {}
+            //- /foo/bar/ignored_bar.rs
+            fn ignored_bar() {}
+            //- /foo/baz/mod.rs
+            fn baz() {}
+            //- /foo/moar/ignored_moar.rs
+            fn ignored_moar() {}
+        "#,
+            expect![[r#"
+                md bar
+                md baz
+            "#]],
+        );
+    }
+
+    #[test]
+    fn nested_in_source_module_completion() {
+        check(
+            r#"
+            //- /lib.rs
+            mod foo;
+            //- /foo.rs
+            mod bar {
+                mod <|>
+            }
+            //- /foo/bar/baz.rs
+            fn baz() {}
+        "#,
+            expect![[r#"
+                md baz;
+            "#]],
+        );
+    }
+
+    // FIXME binary modules are not supported in tests properly
+    // Binary modules are a bit special, they allow importing the modules from `/src/bin`
+    // and that's why are good to test two things:
+    // * no cycles are allowed in mod declarations
+    // * no modules from the parent directory are proposed
+    // Unfortunately, binary modules support is in cargo not rustc,
+    // hence the test does not work now
+    //
+    // #[test]
+    // fn regular_bin_module_completion() {
+    //     check(
+    //         r#"
+    //         //- /src/bin.rs
+    //         fn main() {}
+    //         //- /src/bin/foo.rs
+    //         mod <|>
+    //         //- /src/bin/bar.rs
+    //         fn bar() {}
+    //         //- /src/bin/bar/bar_ignored.rs
+    //         fn bar_ignored() {}
+    //     "#,
+    //         expect![[r#"
+    //             md bar;
+    //         "#]],
+    //     );
+    // }
+
+    #[test]
+    fn already_declared_bin_module_completion_omitted() {
+        check(
+            r#"
+            //- /src/bin.rs
+            fn main() {}
+            //- /src/bin/foo.rs
+            mod <|>
+            //- /src/bin/bar.rs
+            mod foo;
+            fn bar() {}
+            //- /src/bin/bar/bar_ignored.rs
+            fn bar_ignored() {}
+        "#,
+            expect![[r#""#]],
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_qualified_path.rs b/crates/ide/src/completion/complete_qualified_path.rs
index accb09f7e..79de50792 100644
--- a/crates/ide/src/completion/complete_qualified_path.rs
+++ b/crates/ide/src/completion/complete_qualified_path.rs
@@ -13,7 +13,7 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
         None => return,
     };
 
-    if ctx.attribute_under_caret.is_some() {
+    if ctx.attribute_under_caret.is_some() || ctx.mod_declaration_under_caret.is_some() {
         return;
     }
 
diff --git a/crates/ide/src/completion/complete_unqualified_path.rs b/crates/ide/src/completion/complete_unqualified_path.rs
index 1f1b682a7..8eda4b64d 100644
--- a/crates/ide/src/completion/complete_unqualified_path.rs
+++ b/crates/ide/src/completion/complete_unqualified_path.rs
@@ -13,6 +13,7 @@ pub(super) fn complete_unqualified_path(acc: &mut Completions, ctx: &CompletionC
     if ctx.record_lit_syntax.is_some()
         || ctx.record_pat_syntax.is_some()
         || ctx.attribute_under_caret.is_some()
+        || ctx.mod_declaration_under_caret.is_some()
     {
         return;
     }
diff --git a/crates/ide/src/completion/completion_context.rs b/crates/ide/src/completion/completion_context.rs
index 47355d5dc..161f59c1e 100644
--- a/crates/ide/src/completion/completion_context.rs
+++ b/crates/ide/src/completion/completion_context.rs
@@ -77,6 +77,7 @@ pub(crate) struct CompletionContext<'a> {
     pub(super) is_path_type: bool,
     pub(super) has_type_args: bool,
     pub(super) attribute_under_caret: Option<ast::Attr>,
+    pub(super) mod_declaration_under_caret: Option<ast::Module>,
     pub(super) unsafe_is_prev: bool,
     pub(super) if_is_prev: bool,
     pub(super) block_expr_parent: bool,
@@ -152,6 +153,7 @@ impl<'a> CompletionContext<'a> {
             has_type_args: false,
             dot_receiver_is_ambiguous_float_literal: false,
             attribute_under_caret: None,
+            mod_declaration_under_caret: None,
             unsafe_is_prev: false,
             in_loop_body: false,
             ref_pat_parent: false,
@@ -238,7 +240,10 @@ impl<'a> CompletionContext<'a> {
         self.trait_as_prev_sibling = has_trait_as_prev_sibling(syntax_element.clone());
         self.is_match_arm = is_match_arm(syntax_element.clone());
         self.has_item_list_or_source_file_parent =
-            has_item_list_or_source_file_parent(syntax_element);
+            has_item_list_or_source_file_parent(syntax_element.clone());
+        self.mod_declaration_under_caret =
+            find_node_at_offset::<ast::Module>(&file_with_fake_ident, offset)
+                .filter(|module| module.item_list().is_none());
     }
 
     fn fill(
diff --git a/crates/ide/src/completion/patterns.rs b/crates/ide/src/completion/patterns.rs
index c6ae589db..b17ddf133 100644
--- a/crates/ide/src/completion/patterns.rs
+++ b/crates/ide/src/completion/patterns.rs
@@ -115,6 +115,7 @@ pub(crate) fn if_is_prev(element: SyntaxElement) -> bool {
         .filter(|it| it.kind() == IF_KW)
         .is_some()
 }
+
 #[test]
 fn test_if_is_prev() {
     check_pattern_is_applicable(r"if l<|>", if_is_prev);
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
index 25d6f7abd..d9fc25d88 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::{Local, Name, Semantics, VariantDef};
 use ide_db::{
     defs::{classify_name, classify_name_ref, Definition, NameClass, NameRefClass},
     RootDatabase,
@@ -13,8 +13,8 @@ use rustc_hash::FxHashMap;
 use syntax::{
     ast::{self, HasFormatSpecifier},
     AstNode, AstToken, Direction, NodeOrToken, SyntaxElement,
-    SyntaxKind::*,
-    TextRange, WalkEvent, T,
+    SyntaxKind::{self, *},
+    SyntaxNode, SyntaxToken, TextRange, WalkEvent, T,
 };
 
 use crate::FileId;
@@ -454,6 +454,32 @@ fn macro_call_range(macro_call: &ast::MacroCall) -> Option<TextRange> {
     Some(TextRange::new(range_start, range_end))
 }
 
+/// Returns true if the parent nodes of `node` all match the `SyntaxKind`s in `kinds` exactly.
+fn parents_match(mut node: NodeOrToken<SyntaxNode, SyntaxToken>, mut kinds: &[SyntaxKind]) -> bool {
+    while let (Some(parent), [kind, rest @ ..]) = (&node.parent(), kinds) {
+        if parent.kind() != *kind {
+            return false;
+        }
+
+        // FIXME: Would be nice to get parent out of the match, but binding by-move and by-value
+        // in the same pattern is unstable: rust-lang/rust#68354.
+        node = node.parent().unwrap().into();
+        kinds = rest;
+    }
+
+    // Only true if we matched all expected kinds
+    kinds.len() == 0
+}
+
+fn is_consumed_lvalue(
+    node: NodeOrToken<SyntaxNode, SyntaxToken>,
+    local: &Local,
+    db: &RootDatabase,
+) -> bool {
+    // When lvalues are passed as arguments and they're not Copy, then mark them as Consuming.
+    parents_match(node, &[PATH_SEGMENT, PATH, PATH_EXPR, ARG_LIST]) && !local.ty(db).is_copy(db)
+}
+
 fn highlight_element(
     sema: &Semantics<RootDatabase>,
     bindings_shadow_count: &mut FxHashMap<Name, u32>,
@@ -522,6 +548,12 @@ fn highlight_element(
 
                             let mut h = highlight_def(db, def);
 
+                            if let Definition::Local(local) = &def {
+                                if is_consumed_lvalue(name_ref.syntax().clone().into(), local, db) {
+                                    h |= HighlightModifier::Consuming;
+                                }
+                            }
+
                             if let Some(parent) = name_ref.syntax().parent() {
                                 if matches!(parent.kind(), FIELD_EXPR | RECORD_PAT_FIELD) {
                                     if let Definition::Field(field) = def {
@@ -645,21 +677,30 @@ fn highlight_element(
                         .and_then(ast::SelfParam::cast)
                         .and_then(|p| p.mut_token())
                         .is_some();
-                    // closure to enforce lazyness
-                    let self_path = || {
-                        sema.resolve_path(&element.parent()?.parent().and_then(ast::Path::cast)?)
-                    };
+                    let self_path = &element
+                        .parent()
+                        .as_ref()
+                        .and_then(SyntaxNode::parent)
+                        .and_then(ast::Path::cast)
+                        .and_then(|p| sema.resolve_path(&p));
+                    let mut h = HighlightTag::SelfKeyword.into();
                     if self_param_is_mut
-                        || matches!(self_path(),
+                        || matches!(self_path,
                             Some(hir::PathResolution::Local(local))
                                 if local.is_self(db)
                                     && (local.is_mut(db) || local.ty(db).is_mutable_reference())
                         )
                     {
-                        HighlightTag::SelfKeyword | HighlightModifier::Mutable
-                    } else {
-                        HighlightTag::SelfKeyword.into()
+                        h |= HighlightModifier::Mutable
                     }
+
+                    if let Some(hir::PathResolution::Local(local)) = self_path {
+                        if is_consumed_lvalue(element, &local, db) {
+                            h |= HighlightModifier::Consuming;
+                        }
+                    }
+
+                    h
                 }
                 T![ref] => element
                     .parent()
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index d0df2e0ec..cde42024c 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -61,8 +61,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 <span class="punctuation">}</span>
 
 <span class="keyword">impl</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
-    <span class="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">(</span><span class="keyword">mut</span> <span class="self_keyword mutable">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="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">(</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">,</span> <span class="value_param declaration">f</span><span class="punctuation">:</span> <span class="struct">Foo</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">i32</span> <span class="punctuation">{</span>
+        <span class="value_param">f</span><span class="punctuation">.</span><span class="function consuming">baz</span><span class="punctuation">(</span><span class="self_keyword consuming">self</span><span class="punctuation">)</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>
@@ -80,8 +80,8 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 <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="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="value_param declaration">f</span><span class="punctuation">:</span> <span class="struct">FooCopy</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">u32</span> <span class="punctuation">{</span>
+        <span class="value_param">f</span><span class="punctuation">.</span><span class="function">baz</span><span class="punctuation">(</span><span class="self_keyword">self</span><span class="punctuation">)</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>
@@ -144,14 +144,15 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <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="keyword">let</span> <span class="variable declaration">foo2</span> <span class="operator">=</span> <span class="variable mutable">foo</span><span class="punctuation">.</span><span class="unresolved_reference">clone</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">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="variable mutable">foo</span><span class="punctuation">.</span><span class="function consuming">baz</span><span class="punctuation">(</span><span class="variable consuming">foo2</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="variable mutable">copy</span><span class="punctuation">.</span><span class="function">baz</span><span class="punctuation">(</span><span class="variable mutable">copy</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>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index 6f72a29bd..57d4e1252 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -35,8 +35,8 @@ impl Bar for Foo {
 }
 
 impl Foo {
-    fn baz(mut self) -> i32 {
-        self.x
+    fn baz(mut self, f: Foo) -> i32 {
+        f.baz(self)
     }
 
     fn qux(&mut self) {
@@ -54,8 +54,8 @@ struct FooCopy {
 }
 
 impl FooCopy {
-    fn baz(self) -> u32 {
-        self.x
+    fn baz(self, f: FooCopy) -> u32 {
+        f.baz(self)
     }
 
     fn qux(&mut self) {
@@ -118,14 +118,15 @@ fn main() {
     y;
 
     let mut foo = Foo { x, y: x };
+    let foo2 = foo.clone();
     foo.quop();
     foo.qux();
-    foo.baz();
+    foo.baz(foo2);
 
     let mut copy = FooCopy { x };
     copy.quop();
     copy.qux();
-    copy.baz();
+    copy.baz(copy);
 }
 
 enum Option<T> {