Merge #3689

3689: implement fill match arm assist for tuple of enums r=matklad a=JoshMcguigan

This updates the fill match arm assist to work in cases where the user is matching on a tuple of enums. 

Note, for now this does not apply when some match arms exist (other than the trivial `_`), but I think this could be added in the future.

I think this also lays the groundwork for filling match arms when matching on tuples of non-enum values, for example a tuple of an enum and a boolean.

Co-authored-by: Josh Mcguigan <[email protected]>

1 files changed, 14 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index 9f6f1cc53..9257ccd1a 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -136,6 +136,20 @@ pub fn placeholder_pat() -> ast::PlaceholderPat {
     }
 }
 
+/// Creates a tuple of patterns from an interator of patterns.
+///
+/// Invariant: `pats` must be length > 1
+///
+/// FIXME handle `pats` length == 1
+pub fn tuple_pat(pats: impl IntoIterator<Item = ast::Pat>) -> ast::TuplePat {
+    let pats_str = pats.into_iter().map(|p| p.to_string()).join(", ");
+    return from_text(&format!("({})", pats_str));
+
+    fn from_text(text: &str) -> ast::TuplePat {
+        ast_from_text(&format!("fn f({}: ())", text))
+    }
+}
+
 pub fn tuple_struct_pat(
     path: ast::Path,
     pats: impl IntoIterator<Item = ast::Pat>,