From bd56a745624a5246fac7fe80d11a9cd6fb361ddb Mon Sep 17 00:00:00 2001
From: Huang-404-Q <129407632+Huang-404-Q@users.noreply.github.com>
Date: Sat, 24 Oct 2026 14:19:14 +0800
Subject: [PATCH] Fix halt_error adding a newline to non-string output (#3694)

The manual says halt_error prints its input with no decoration, not
even a newline, but non-string values such as {"a":"xyz"} were printed
with a trailing newline.

Dump non-string values to JSON and print them the same way as strings,
so {"a":"xyz"} | halt_error(1) now writes exactly {"a":"xyz"} to stderr.
---
 src/main.c   | 15 ++++++++-------
 tests/shtest |  2 +-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/main.c b/src/main.c
index abe4e959..43f7338c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -222,15 +222,16 @@ static int process(jq_state *jq, jv value, int flags, int dumpopts, int options)
       ret = JQ_ERROR_UNKNOWN;
     jv_free(exit_code);
     jv error_message = jq_get_error_message(jq);
-    if (jv_get_kind(error_message) == JV_KIND_STRING) {
-      // No prefix should be added to the output of `halt_error`.
-      priv_fwrite(jv_string_value(error_message), jv_string_length_bytes(jv_copy(error_message)),
-          stderr, dumpopts & JV_PRINT_ISATTY);
-    } else if (jv_get_kind(error_message) == JV_KIND_NULL) {
+    if (jv_get_kind(error_message) == JV_KIND_NULL) {
       // Halt with no output
     } else if (jv_is_valid(error_message)) {
-      error_message = jv_dump_string(error_message, 0);
-      fprintf(stderr, "%s\n", jv_string_value(error_message));
+      if (jv_get_kind(error_message) != JV_KIND_STRING) {
+        error_message = jv_dump_string(error_message, 0);
+      }
+      // No prefix or trailing newline should be added to the output of
+      // `halt_error`.
+      priv_fwrite(jv_string_value(error_message), jv_string_length_bytes(jv_copy(error_message)),
+          stderr, dumpopts & JV_PRINT_ISATTY);
     } // else no message on stderr; use --debug-trace to see a message
     fflush(stderr);
     jv_free(error_message);
diff --git a/tests/shtest b/tests/shtest
index 5f4185a9..941c0cac 100755
--- a/tests/shtest
+++ b/tests/shtest
@@ -566,7 +566,7 @@ if [ "$($VALGRIND $Q $JQ -n '"x\u0000y\u0000z" | halt_error(1)' 2>&1 | tr '\0' '
     echo "jq halt_error(1) had unexpected output" 1>&2
     exit 1
 fi
-if [ "$($VALGRIND $Q $JQ -n '{"a":"xyz"} | halt_error(1)' 2>&1)" != '{"a":"xyz"}' ]; then
+if [ "$($VALGRIND $Q $JQ -n '{"a":"xyz"} | halt_error(1)' 2>&1 || echo "z")" != '{"a":"xyz"}z' ]; then
     echo "jq halt_error(1) had unexpected output" 1>&2
     exit 1
 fi