Re: Build error in next-20260223 gcc-plugins/latent_entropy_plugin.so

[Kees Cook <kees@kernel.org>]

On Sat, Mar 14, 2026 at 03:44:08PM +0100, Ingo Saitz wrote:
> On Sat, Mar 14, 2026 at 02:50:46PM +0100, Ingo Saitz wrote:
> > I attached [...]
> 
> Grml, here you go
> 
>     Ingo
> -- 
> const_cast<long double>(Λ)

> From 552485b879d19780afd3614d69508c3ea7cb242f Mon Sep 17 00:00:00 2001
> From: Ingo Saitz <ingo@hannover.ccc.de>
> Date: Sat, 14 Mar 2026 14:24:56 +0100
> Subject: [PATCH] Replace CONST_CAST with const_cast<>.
> 
> For gcc-16, this was removed in gcc trunk
> 
> see commits
>   c3d96ff9e916c02584aa081f03ab999292efbb50
>   458c7926d48959abcb2c1adaa22458e27459a551
> ---
>  scripts/gcc-plugins/gcc-common.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/scripts/gcc-plugins/gcc-common.h b/scripts/gcc-plugins/gcc-common.h
> index 8f1b3500f8e2..7b3517b31e0a 100644
> --- a/scripts/gcc-plugins/gcc-common.h
> +++ b/scripts/gcc-plugins/gcc-common.h
> @@ -309,7 +309,7 @@ typedef const gimple *const_gimple_ptr;
>  #define gimple gimple_ptr
>  #define const_gimple const_gimple_ptr
>  #undef CONST_CAST_GIMPLE
> -#define CONST_CAST_GIMPLE(X) CONST_CAST(gimple, (X))
> +#define CONST_CAST_GIMPLE(X) const_cast<gimple>((X))
>  
>  /* gimple related */
>  static inline gimple gimple_build_assign_with_ops(enum tree_code subcode, tree lhs, tree op1, tree op2 MEM_STAT_DECL)
> @@ -414,7 +414,7 @@ static inline void ipa_remove_stmt_references(symtab_node *referring_node, gimpl
>  #ifdef __cplusplus
>  static inline void debug_tree(const_tree t)
>  {
> -	debug_tree(CONST_CAST_TREE(t));
> +	debug_tree(const_cast<tree>(t));
>  }
>  
>  static inline void debug_gimple_stmt(const_gimple s)
> @@ -422,7 +422,7 @@ static inline void debug_gimple_stmt(const_gimple s)
>  	debug_gimple_stmt(CONST_CAST_GIMPLE(s));
>  }
>  #else
> -#define debug_tree(t) debug_tree(CONST_CAST_TREE(t))
> +#define debug_tree(t) debug_tree(const_cast<tree>(t))
>  #define debug_gimple_stmt(s) debug_gimple_stmt(CONST_CAST_GIMPLE(s))
>  #endif

Thanks for this!

Should CONST_CAST_TREE be explicitly defined instead, to match
CONST_CAST_GIMPLE in the this header file? It seems weird to have one of
two done this way: we should either do both or neither (CONST_CAST_GIMPLE
is only used in the header file too).

Is const_cast<gimple> and const_cast<tree> valid back through GCC 8
(earliest Linux-supported GCC)?

-Kees

-- 
Kees Cook