1 files changed, 74 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/repr.rs b/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/repr.rs
new file mode 100644
index 000000000..a29417133
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/repr.rs
@@ -0,0 +1,74 @@
+//! Completion for representations.
+
+use ide_db::SymbolKind;
+use syntax::ast;
+
+use crate::{context::CompletionContext, item::CompletionItem, Completions};
+
+pub(super) fn complete_repr(
+    acc: &mut Completions,
+    ctx: &CompletionContext<'_>,
+    input: ast::TokenTree,
+) {
+    if let Some(existing_reprs) = super::parse_comma_sep_expr(input) {
+        for &ReprCompletion { label, snippet, lookup, collides } in REPR_COMPLETIONS {
+            let repr_already_annotated = existing_reprs
+                .iter()
+                .filter_map(|expr| match expr {
+                    ast::Expr::PathExpr(path) => path.path()?.as_single_name_ref(),
+                    ast::Expr::CallExpr(call) => match call.expr()? {
+                        ast::Expr::PathExpr(path) => path.path()?.as_single_name_ref(),
+                        _ => None,
+                    },
+                    _ => None,
+                })
+                .any(|it| {
+                    let text = it.text();
+                    lookup.unwrap_or(label) == text || collides.contains(&text.as_str())
+                });
+            if repr_already_annotated {
+                continue;
+            }
+
+            let mut item = CompletionItem::new(SymbolKind::BuiltinAttr, ctx.source_range(), label);
+            if let Some(lookup) = lookup {
+                item.lookup_by(lookup);
+            }
+            if let Some((snippet, cap)) = snippet.zip(ctx.config.snippet_cap) {
+                item.insert_snippet(cap, snippet);
+            }
+            item.add_to(acc);
+        }
+    }
+}
+
+struct ReprCompletion {
+    label: &'static str,
+    snippet: Option<&'static str>,
+    lookup: Option<&'static str>,
+    collides: &'static [&'static str],
+}
+
+const fn attr(label: &'static str, collides: &'static [&'static str]) -> ReprCompletion {
+    ReprCompletion { label, snippet: None, lookup: None, collides }
+}
+
+#[rustfmt::skip]
+const REPR_COMPLETIONS: &[ReprCompletion] = &[
+    ReprCompletion { label: "align($0)", snippet: Some("align($0)"), lookup: Some("align"), collides: &["transparent", "packed"] },
+    attr("packed", &["transparent", "align"]),
+    attr("transparent", &["C", "u8", "u16", "u32", "u64", "u128", "usize", "i8", "i16", "i32", "i64", "i128", "isize"]),
+    attr("C", &["transparent"]),
+    attr("u8",     &["transparent", "u16", "u32", "u64", "u128", "usize", "i8", "i16", "i32", "i64", "i128", "isize"]),
+    attr("u16",    &["transparent", "u8", "u32", "u64", "u128", "usize", "i8", "i16", "i32", "i64", "i128", "isize"]),
+    attr("u32",    &["transparent", "u8", "u16", "u64", "u128", "usize", "i8", "i16", "i32", "i64", "i128", "isize"]),
+    attr("u64",    &["transparent", "u8", "u16", "u32", "u128", "usize", "i8", "i16", "i32", "i64", "i128", "isize"]),
+    attr("u128",   &["transparent", "u8", "u16", "u32", "u64", "usize", "i8", "i16", "i32", "i64", "i128", "isize"]),
+    attr("usize",  &["transparent", "u8", "u16", "u32", "u64", "u128", "i8", "i16", "i32", "i64", "i128", "isize"]),
+    attr("i8",     &["transparent", "u8", "u16", "u32", "u64", "u128", "usize", "i16", "i32", "i64", "i128", "isize"]),
+    attr("i16",    &["transparent", "u8", "u16", "u32", "u64", "u128", "usize", "i8", "i32", "i64", "i128", "isize"]),
+    attr("i32",    &["transparent", "u8", "u16", "u32", "u64", "u128", "usize", "i8", "i16", "i64", "i128", "isize"]),
+    attr("i64",    &["transparent", "u8", "u16", "u32", "u64", "u128", "usize", "i8", "i16", "i32", "i128", "isize"]),
+    attr("i28",    &["transparent", "u8", "u16", "u32", "u64", "u128", "usize", "i8", "i16", "i32", "i64", "isize"]),
+    attr("isize",  &["transparent", "u8", "u16", "u32", "u64", "u128", "usize", "i8", "i16", "i32", "i64", "i128"]),
+];