[gcc r14-8101] gccrs: Add an explicit value to proc macro enum kind

[Arthur Cohen]

https://gcc.gnu.org/g:10699fb34a2969102afe3519caae62dddb8075fc

commit r14-8101-g10699fb34a2969102afe3519caae62dddb8075fc
Author: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
Date:   Wed Sep 27 16:21:25 2023 +0200

    gccrs: Add an explicit value to proc macro enum kind
    
    We'll need this value in the final binary, it should therefore be kept
    explicit.
    
    libgrust/ChangeLog:
    
            * libproc_macro_internal/proc_macro.h (enum ProcmacroTag): Add
            explicit value for proc macro tag enum.
    
    Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

Diff:
---
 libgrust/libproc_macro_internal/proc_macro.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libgrust/libproc_macro_internal/proc_macro.h b/libgrust/libproc_macro_internal/proc_macro.h
index 457ec4693f6..9e142ffa79f 100644
--- a/libgrust/libproc_macro_internal/proc_macro.h
+++ b/libgrust/libproc_macro_internal/proc_macro.h
@@ -66,7 +66,7 @@ struct Bang
 
 enum ProcmacroTag
 {
-  CUSTOM_DERIVE,
+  CUSTOM_DERIVE = 0,
   ATTR,
   BANG,
 };