From 1717690a64c71a394fb091763ea4bb18375d7dc3 Mon Sep 17 00:00:00 2001
From: Yuya Nishihara <yuya@tcha.org>
Date: Wed, 16 Nov 2022 16:47:00 +0900
Subject: [PATCH] revset: leverage SOI/EOI markers to detect incomplete parser
 input

The error message is still a bit cryptic, but I don't think it's worse than
the original "incomplete parse" error.

https://pest.rs/book/grammars/syntax.html#start-and-end-of-input
---
 lib/src/revset.pest         |  2 ++
 lib/src/revset.rs           | 14 +-------------
 tests/test_revset_output.rs | 17 +++++++++++++++++
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/lib/src/revset.pest b/lib/src/revset.pest
index f96f05c7a..02f1b5414 100644
--- a/lib/src/revset.pest
+++ b/lib/src/revset.pest
@@ -66,3 +66,5 @@ infix_expression = {
 expression = {
   whitespace* ~ infix_expression ~ whitespace*
 }
+
+program = _{ SOI ~ expression ~ EOI }
diff --git a/lib/src/revset.rs b/lib/src/revset.rs
index 3ea998ba8..8f600c6e1 100644
--- a/lib/src/revset.rs
+++ b/lib/src/revset.rs
@@ -857,20 +857,8 @@ pub fn parse(
     revset_str: &str,
     workspace_ctx: Option<&RevsetWorkspaceContext>,
 ) -> Result<Rc<RevsetExpression>, RevsetParseError> {
-    let mut pairs = RevsetParser::parse(Rule::expression, revset_str)?;
+    let mut pairs = RevsetParser::parse(Rule::program, revset_str)?;
     let first = pairs.next().unwrap();
-    assert!(pairs.next().is_none());
-    if first.as_span().end() != revset_str.len() {
-        let pos = pest::Position::new(revset_str, first.as_span().end()).unwrap();
-        let err = pest::error::Error::new_from_pos(
-            pest::error::ErrorVariant::CustomError {
-                message: "Incomplete parse".to_string(),
-            },
-            pos,
-        );
-        return Err(RevsetParseError::from(err));
-    }
-
     parse_expression_rule(first.into_inner(), workspace_ctx)
 }
 
diff --git a/tests/test_revset_output.rs b/tests/test_revset_output.rs
index 1de2a351d..45bd883d7 100644
--- a/tests/test_revset_output.rs
+++ b/tests/test_revset_output.rs
@@ -16,6 +16,23 @@ use common::TestEnvironment;
 
 pub mod common;
 
+#[test]
+fn test_syntax_error() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+
+    let stderr = test_env.jj_cmd_failure(&repo_path, &["log", "-r", "x &"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Error: Failed to parse revset:  --> 1:4
+      |
+    1 | x &
+      |    ^---
+      |
+      = expected range_expression
+    "###);
+}
+
 #[test]
 fn test_bad_function_call() {
     let test_env = TestEnvironment::default();