From 4b5b56452ba2dba15753a8b62ad8b987dbbc4e9c Mon Sep 17 00:00:00 2001
From: Johannes Altmanninger <aclopte@gmail.com>
Date: Sun, 3 Apr 2022 16:29:13 +0200
Subject: [PATCH] Make string syntax error location a bit more precise

String tokens are subdivided by command substitutions. Some syntax errors
can occur in the gap between two command substitutions. Make the caret point
to the start of that gap, instead of the token start.
---
 src/parse_util.cpp                      | 2 +-
 tests/checks/syntax-error-location.fish | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/parse_util.cpp b/src/parse_util.cpp
index 6cc381efb..10efed238 100644
--- a/src/parse_util.cpp
+++ b/src/parse_util.cpp
@@ -959,7 +959,7 @@ parser_test_error_bits_t parse_util_detect_errors_in_argument(const ast::argumen
         wcstring unesc;
         if (!unescape_string(arg_src.c_str() + begin, end - begin, &unesc, UNESCAPE_SPECIAL)) {
             if (out_errors) {
-                append_syntax_error(out_errors, source_start, L"Invalid token '%ls'",
+                append_syntax_error(out_errors, source_start + begin, L"Invalid token '%ls'",
                                     arg_src.c_str());
             }
             return 1;
diff --git a/tests/checks/syntax-error-location.fish b/tests/checks/syntax-error-location.fish
index 3f2aebfdc..52ef3a3a9 100644
--- a/tests/checks/syntax-error-location.fish
+++ b/tests/checks/syntax-error-location.fish
@@ -39,6 +39,11 @@ $fish -c 'echo "unfinished "$(subshell' 2>| string replace -r '.*' '<$0>'
 # CHECK: <echo "unfinished "$(subshell>
 # CHECK: <                   ^>
 
+$fish -c 'echo "ok $(echo still ok)syntax error: \x"' 2>| string replace -r '.*' '<$0>'
+# CHECK: <fish: Invalid token '"ok $(echo still ok)syntax error: \x"'>
+# CHECK: <echo "ok $(echo still ok)syntax error: \x">
+# CHECK: <                         ^>
+
 echo "function error" >$TMPDIR/error.fish
 $fish -c "set -g fish_function_path $(string escape $TMPDIR); error"
 # CHECKERR: ~/temp/error.fish (line 1): Missing end to balance this function definition
@@ -47,6 +52,6 @@ $fish -c "set -g fish_function_path $(string escape $TMPDIR); error"
 # CHECKERR: from sourcing file ~/temp/error.fish
 # CHECKERR: source: Error while reading file '{{.*}}/error.fish'
 # CHECKERR: fish: Unknown command: error
-# CHECKERR: fish: 
+# CHECKERR: fish:
 # CHECKERR: set -g fish_function_path {{.*}}; error
 # CHECKERR: ^