[gnutls-devel] GnuTLS | VLA in _gnutls_dump_vector() (#1336)

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Mon Mar 14 11:30:42 CET 2022

Gisle Vanem created an issue: https://gitlab.com/gnutls/gnutls/-/issues/1336

Compiling the `debug.c` file with `cl -c -DDEBUG ...` (with MSVC-2019), yields this error:
debug.c(47): error C2057: expected constant expression
debug.c(47): error C2466: cannot allocate an array of constant size 0
debug.c(47): error C2133: 'buf_hex': unknown size
debug.c(51): warning C4034: sizeof returns 0

Wouldn't it be better by using `alloca()` for MSVC in this case:
--- a/lib/debug.c 2022-03-13 16:34:15
+++ b/lib/debug.c 2022-03-14 11:28:50
@@ -44,7 +44,11 @@
 _gnutls_dump_vector(const char *prefix, const uint8_t * a, size_t a_size)
-       char buf_hex[2 * a_size + 1];
+#ifdef _MSC_VER
+       char *buf_hex = alloca (2 * a_size + 1);
+       char *buf_hex[2 * a_size + 1];

But I cannot see this functions is called anywhere. So why is it there?

I made a similar [issue](https://gitlab.com/gnutls/gnutls/-/issues/248) 4 years ago.
And I'm amazed MSVC is still not fully supported.

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