1 files changed, 73 insertions, 0 deletions

diff --git a/crates/ra_ide_api/src/completion/complete_struct_literal.rs b/crates/ra_ide_api/src/completion/complete_struct_literal.rs
new file mode 100644
index 000000000..f8dd2baad
--- /dev/null
+++ b/crates/ra_ide_api/src/completion/complete_struct_literal.rs
@@ -0,0 +1,73 @@
+use hir::{Ty, AdtDef, Docs};
+
+use crate::completion::{CompletionContext, Completions, CompletionItem, CompletionItemKind};
+use crate::completion::completion_item::CompletionKind;
+
+/// Complete fields in fields literals.
+pub(super) fn complete_struct_literal(acc: &mut Completions, ctx: &CompletionContext) {
+    let (function, struct_lit) = match (&ctx.function, ctx.struct_lit_syntax) {
+        (Some(function), Some(struct_lit)) => (function, struct_lit),
+        _ => return,
+    };
+    let infer_result = function.infer(ctx.db);
+    let syntax_mapping = function.body_syntax_mapping(ctx.db);
+    let expr = match syntax_mapping.node_expr(struct_lit.into()) {
+        Some(expr) => expr,
+        None => return,
+    };
+    let ty = infer_result[expr].clone();
+    let (adt, substs) = match ty {
+        Ty::Adt { def_id, ref substs, .. } => (def_id, substs),
+        _ => return,
+    };
+    match adt {
+        AdtDef::Struct(s) => {
+            for field in s.fields(ctx.db) {
+                CompletionItem::new(
+                    CompletionKind::Reference,
+                    ctx.source_range(),
+                    field.name(ctx.db).to_string(),
+                )
+                .kind(CompletionItemKind::Field)
+                .detail(field.ty(ctx.db).subst(substs).to_string())
+                .set_documentation(field.docs(ctx.db))
+                .add_to(acc);
+            }
+        }
+
+        // TODO unions
+        AdtDef::Enum(_) => (),
+    };
+}
+
+#[cfg(test)]
+mod tests {
+    use insta::assert_debug_snapshot_matches;
+    use crate::completion::{CompletionItem, CompletionKind};
+
+    fn complete(code: &str) -> Vec<CompletionItem> {
+        crate::completion::completion_item::do_completion(code, CompletionKind::Reference)
+    }
+
+    #[test]
+    fn test_struct_literal_field() {
+        let completions = complete(
+            r"
+            struct A { the_field: u32 }
+            fn foo() {
+               A { the<|> }
+            }
+            ",
+        );
+        assert_debug_snapshot_matches!(completions, @r###"[
+    CompletionItem {
+        label: "the_field",
+        source_range: [83; 86),
+        delete: [83; 86),
+        insert: "the_field",
+        kind: Field,
+        detail: "u32"
+    }
+]"###);
+    }
+}