Merge #3513

3513: Completion in macros r=matklad a=flodiebold

I experimented a bit with completion in macros. It's kind of working, but there are a lot of rough edges.

 - I'm trying to expand the macro call with the inserted fake token. This requires some hacky additions on the HIR level to be able to do "hypothetical" expansions. There should probably be a nicer API for this, if we want to do it this way. I'm not sure whether it's worth it, because we still can't do a lot if the original macro call didn't expand in nearly the same way. E.g. if we have something like `println!("", x<|>)` the expansions will look the same and everything is fine; but in that case we could maybe have achieved the same result in a simpler way. If we have something like `m!(<|>)` where `m!()` doesn't even expand or expands to something very different, we don't really know what to do anyway.
 - Relatedly, there are a lot of cases where this doesn't work because either the original call or the hypothetical call doesn't expand. E.g. if we have `m!(x.<|>)` the original token tree doesn't parse as an expression; if we have `m!(match x { <|> })` the hypothetical token tree doesn't parse. It would be nice if we could have better error recovery in these cases.

Co-authored-by: Florian Diebold <[email protected]>

1 files changed, 63 insertions, 2 deletions

diff --git a/crates/ra_ide/src/completion/complete_postfix.rs b/crates/ra_ide/src/completion/complete_postfix.rs
index 8a74f993a..65ecea125 100644
--- a/crates/ra_ide/src/completion/complete_postfix.rs
+++ b/crates/ra_ide/src/completion/complete_postfix.rs
@@ -67,8 +67,8 @@ pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
 
 fn postfix_snippet(ctx: &CompletionContext, label: &str, detail: &str, snippet: &str) -> Builder {
     let edit = {
-        let receiver_range =
-            ctx.dot_receiver.as_ref().expect("no receiver available").syntax().text_range();
+        let receiver_syntax = ctx.dot_receiver.as_ref().expect("no receiver available").syntax();
+        let receiver_range = ctx.sema.original_range(receiver_syntax).range;
         let delete_range = TextRange::from_to(receiver_range.start(), ctx.source_range().end());
         TextEdit::replace(delete_range, snippet.to_string())
     };
@@ -279,4 +279,65 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn works_in_simple_macro() {
+        assert_debug_snapshot!(
+            do_postfix_completion(
+                r#"
+                macro_rules! m { ($e:expr) => { $e } }
+                fn main() {
+                    let bar: u8 = 12;
+                    m!(bar.b<|>)
+                }
+                "#,
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "box",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "Box::new(bar)",
+                detail: "Box::new(expr)",
+            },
+            CompletionItem {
+                label: "dbg",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "dbg!(bar)",
+                detail: "dbg!(expr)",
+            },
+            CompletionItem {
+                label: "match",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "match bar {\n    ${1:_} => {$0\\},\n}",
+                detail: "match expr {}",
+            },
+            CompletionItem {
+                label: "not",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "!bar",
+                detail: "!expr",
+            },
+            CompletionItem {
+                label: "ref",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "&bar",
+                detail: "&expr",
+            },
+            CompletionItem {
+                label: "refm",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "&mut bar",
+                detail: "&mut expr",
+            },
+        ]
+        "###
+        );
+    }
 }