vm: don't treat offset 0 special for exceptions

Try to resolve the source offset to line and character position and only
fall back to report the location as instruction offset if we weren't able
to determine the line number.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 5 insertions, 2 deletions

diff --git a/vm.c b/vm.c
index 3a6e39e..1cf24ab 100644
--- a/vm.c
+++ b/vm.c
@@ -902,11 +902,11 @@ uc_vm_capture_stacktrace(uc_vm_t *vm, size_t i)
 static uc_value_t *
 uc_vm_get_error_context(uc_vm_t *vm)
 {
+	size_t offset, i, byte, line;
 	uc_value_t *stacktrace;
 	uc_callframe_t *frame;
 	uc_stringbuf_t *buf;
 	uc_chunk_t *chunk;
-	size_t offset, i;
 
 	/* skip to first non-native function call frame */
 	for (i = vm->callframes.count; i > 1; i--)
@@ -924,7 +924,10 @@ uc_vm_get_error_context(uc_vm_t *vm)
 
 	buf = ucv_stringbuf_new();
 
-	if (offset)
+	byte = offset;
+	line = uc_source_get_line(uc_program_function_source(frame->closure->function), &byte);
+
+	if (line)
 		uc_error_context_format(buf, uc_vm_frame_source(frame), stacktrace, offset);
 	else if (frame->ip != chunk->entries)
 		ucv_stringbuf_printf(buf, "At instruction %zu", (frame->ip - chunk->entries) - 1);