Implement variable length arrays

Variably modified types are required for C23.

Since QBE doesn't currently support saving and restoring the stack
pointer, a current limitation is that we can't reclaim stack space
from VLAs that go out of scope. This is potentially problematic for
VLAs appearing in a loop, but this case is uncommon enough that it
is silently ignored for now.

Implements: https://todo.sr.ht/~mcf/cproc/1
References: https://todo.sr.ht/~mcf/cproc/88
Co-authored-by: Michael Forney <mforney@mforney.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/configure b/configure
index 7d2de5c..dab1bf3 100755
--- a/configure
+++ b/configure
@@ -149,7 +149,6 @@ static const char *const preprocesscmd[] = {
 	/* we don't yet support these optional features */
 	"-D", "__STDC_NO_ATOMICS__",
 	"-D", "__STDC_NO_COMPLEX__",
-	"-D", "__STDC_NO_VLA__",
 	"-U", "__SIZEOF_INT128__",
 
 	/* we don't generate position-independent code */