[gcc r14-3411] rtl: Forward declare rtx_code

[Richard Earnshaw <rearnsha@gcc.gnu.org>]

https://gcc.gnu.org/g:3e086a12c273e5abb45d0228dc624acf97871ef3

commit r14-3411-g3e086a12c273e5abb45d0228dc624acf97871ef3
Author: Richard Earnshaw <rearnsha@arm.com>
Date:   Thu Jul 27 17:28:30 2023 +0100

    rtl: Forward declare rtx_code
    
    Now that we require C++ 11, we can safely forward declare rtx_code
    so that we can use it in target hooks.
    
    gcc/ChangeLog
            * coretypes.h (rtx_code): Add forward declaration.
            * rtl.h (rtx_code): Make compatible with forward declaration.

Diff:
---
 gcc/coretypes.h | 4 ++++
 gcc/rtl.h       | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/gcc/coretypes.h b/gcc/coretypes.h
index 3e9a2f19e27b..f86dc169a40b 100644
--- a/gcc/coretypes.h
+++ b/gcc/coretypes.h
@@ -101,6 +101,10 @@ typedef gimple *gimple_seq;
 struct gimple_stmt_iterator;
 class code_helper;
 
+/* Forward declare rtx_code, so that we can use it in target hooks without
+   needing to pull in rtl.h.  */
+enum rtx_code : unsigned;
+
 /* Forward decls for leaf gimple subclasses (for individual gimple codes).
    Keep this in the same order as the corresponding codes in gimple.def.  */
 
diff --git a/gcc/rtl.h b/gcc/rtl.h
index e1c51156f909..0e9491b89b4d 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -45,7 +45,7 @@ class predefined_function_abi;
 /* Register Transfer Language EXPRESSIONS CODES */
 
 #define RTX_CODE	enum rtx_code
-enum rtx_code  {
+enum rtx_code : unsigned {
 
 #define DEF_RTL_EXPR(ENUM, NAME, FORMAT, CLASS)   ENUM ,
 #include "rtl.def"		/* rtl expressions are documented here */