From 3e84434c695379dd2b56415c5cec46990488d007 Mon Sep 17 00:00:00 2001 From: Michael Davis Date: Tue, 8 Nov 2022 18:58:27 -0600 Subject: [PATCH] Fix panic from indenting on tree with errors `deepest_preceding` is known to be a descendant of `node`. Repeated calls of `Node::parent` _should_ eventually turn `deepest_preceding` into `node`, but when the node is errored (the tree contains a syntax error), `Node::parent` returns None. In the typescript case: if(true) &&true // ^ press enter here The tree is: (program [0, 0] - [1, 0] (if_statement [0, 0] - [0, 15] condition: (parenthesized_expression [0, 2] - [0, 8] (true [0, 3] - [0, 7])) consequence: (expression_statement [0, 8] - [0, 15] (binary_expression [0, 8] - [0, 15] left: (identifier [0, 8] - [0, 8]) right: (true [0, 11] - [0, 15]))))) `node` is the `program` node and `deepest_preceding` is the `binary_expression`. The tree is errored on the `binary_expression` node with `(MISSING identifier [0, 8] - [0, 8])`. In the C++ case: ; << // press enter after the ';' The tree is: (translation_unit [0, 0] - [1, 0] (expression_statement [0, 0] - [0, 1]) (ERROR [0, 1] - [0, 4] (identifier [0, 1] - [0, 1]))) `node` is the `translation_unit` and `deepest_preceding` is the `ERROR` node. In both cases, `Node::parent` on the errored node returns None. --- helix-core/src/indent.rs | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/helix-core/src/indent.rs b/helix-core/src/indent.rs index 1c813c9a..d6aa5edb 100644 --- a/helix-core/src/indent.rs +++ b/helix-core/src/indent.rs @@ -511,8 +511,12 @@ fn extend_nodes<'a>( *node = deepest_preceding; break; } - // This parent always exists since node is an ancestor of deepest_preceding - deepest_preceding = deepest_preceding.parent().unwrap(); + // If the tree contains a syntax error, `deepest_preceding` may not + // have a parent despite being a descendant of `node`. + deepest_preceding = match deepest_preceding.parent() { + Some(parent) => parent, + None => return, + } } }