From d3bfc615245b8c7ef4e3dc10b32673e2c14be834 Mon Sep 17 00:00:00 2001
From: JT <547158+jntrnr@users.noreply.github.com>
Date: Mon, 10 Jan 2022 13:52:01 +1100
Subject: [PATCH] Don't panic on alias errors (#713)

---
 crates/nu-parser/src/parser.rs | 27 +++++++++++++++++++++------
 src/tests/test_parser.rs       |  9 +++++++++
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/crates/nu-parser/src/parser.rs b/crates/nu-parser/src/parser.rs
index 59ff117b1b..72dd36f22f 100644
--- a/crates/nu-parser/src/parser.rs
+++ b/crates/nu-parser/src/parser.rs
@@ -748,6 +748,7 @@ pub fn parse_call(
     let mut pos = 0;
     let cmd_start = pos;
     let mut name_spans = vec![];
+    let mut name = vec![];
 
     for word_span in spans[cmd_start..].iter() {
         // Find the longest group of words that could form a command
@@ -759,11 +760,17 @@ pub fn parse_call(
 
         name_spans.push(*word_span);
 
-        let name = working_set.get_span_contents(span(&name_spans));
+        let name_part = working_set.get_span_contents(*word_span);
+        if name.is_empty() {
+            name.extend(name_part);
+        } else {
+            name.push(b' ');
+            name.extend(name_part);
+        }
 
         if expand_aliases {
             // If the word is an alias, expand it and re-parse the expression
-            if let Some(expansion) = working_set.find_alias(name) {
+            if let Some(expansion) = working_set.find_alias(&name) {
                 trace!("expanding alias");
 
                 let orig_span = spans[pos];
@@ -801,8 +808,7 @@ pub fn parse_call(
         pos += 1;
     }
 
-    let name = working_set.get_span_contents(span(&name_spans));
-    let mut maybe_decl_id = working_set.find_decl(name);
+    let mut maybe_decl_id = working_set.find_decl(&name);
 
     while maybe_decl_id.is_none() {
         // Find the longest command match
@@ -814,8 +820,17 @@ pub fn parse_call(
         name_spans.pop();
         pos -= 1;
 
-        let name = working_set.get_span_contents(span(&name_spans));
-        maybe_decl_id = working_set.find_decl(name);
+        let mut name = vec![];
+        for name_span in &name_spans {
+            let name_part = working_set.get_span_contents(*name_span);
+            if name.is_empty() {
+                name.extend(name_part);
+            } else {
+                name.push(b' ');
+                name.extend(name_part);
+            }
+        }
+        maybe_decl_id = working_set.find_decl(&name);
     }
 
     if let Some(decl_id) = maybe_decl_id {
diff --git a/src/tests/test_parser.rs b/src/tests/test_parser.rs
index ac27807666..64fa65a66c 100644
--- a/src/tests/test_parser.rs
+++ b/src/tests/test_parser.rs
@@ -139,3 +139,12 @@ fn multiline_pipe_in_block() -> TestResult {
 fn bad_short_flag() -> TestResult {
     fail_test(r#"def foo3 [-l?:int] { $l }"#, "short flag")
 }
+
+#[test]
+fn alias_with_error_doesnt_panic() -> TestResult {
+    fail_test(
+        r#"alias s = shells
+        s ."#,
+        "extra positional",
+    )
+}