[PATCH] Fix up bootstrap with GCC 4.[89] after RAII auto_mpfr and autp_mpz [PR109589]

[Jakub Jelinek <jakub@redhat.com>]

Hi!

On Tue, Apr 18, 2023 at 03:39:41PM +0200, Richard Biener via Gcc-patches wrote:
> The following adds two RAII classes, one for mpz_t and one for mpfr_t
> making object lifetime management easier.  Both formerly require
> explicit initialization with {mpz,mpfr}_init and release with
> {mpz,mpfr}_clear.

This unfortunately broke bootstrap when using GCC 4.8.x or 4.9.x as
it uses deleted friends which weren't supported until PR62101 fixed
them in 2014 for GCC 5.

The following patch adds an workaround, not deleting those friends
for those old versions.
While it means if people add those mp*_{init{,2},clear} calls on auto_mp*
objects they won't notice when doing non-bootstrap builds using
very old system compilers, people should be bootstrapping their changes
and it will be caught during bootstraps even when starting with those
old compilers, plus most people actually use much newer compilers
when developing.

Bootstrapped/regtested on x86_64-linux and i686-linux (with gcc 12.1.1
as system compiler) and powerpc64-linux and powerpc64le-linux (with gcc
4.8.5 as system compiler, where it previously failed bootstrap).
Ok for trunk?

2023-04-22  Jakub Jelinek  <jakub@redhat.com>

	PR bootstrap/109589
	* system.h (class auto_mpz): Workaround PR62101 bug in GCC 4.8 and 4.9.
	* realmpfr.h (class auto_mpfr): Likewise.

--- gcc/system.h.jj	2023-04-20 09:36:09.097375720 +0200
+++ gcc/system.h	2023-04-21 20:13:09.212049563 +0200
@@ -714,8 +714,11 @@ public:
   auto_mpz (const auto_mpz &) = delete;
   auto_mpz &operator= (const auto_mpz &) = delete;
 
+#if GCC_VERSION < 4008 || GCC_VERSION >= 5000
+  /* GCC 4.8 and 4.9 don't support this, only fixed in PR62101 for 5.0.  */
   friend void mpz_clear (auto_mpz&) = delete;
   friend void mpz_init (auto_mpz&) = delete;
+#endif
 
 private:
   mpz_t m_mpz;
--- gcc/realmpfr.h.jj	2023-04-20 09:36:09.066376175 +0200
+++ gcc/realmpfr.h	2023-04-21 20:13:36.191663089 +0200
@@ -37,9 +37,12 @@ public:
   auto_mpfr (const auto_mpfr &) = delete;
   auto_mpfr &operator= (const auto_mpfr &) = delete;
 
+#if GCC_VERSION < 4008 || GCC_VERSION >= 5000
+  /* GCC 4.8 and 4.9 don't support this, only fixed in PR62101 for 5.0.  */
   friend void mpfr_clear (auto_mpfr&) = delete;
   friend void mpfr_init (auto_mpfr&) = delete;
   friend void mpfr_init2 (auto_mpfr&, mpfr_prec_t) = delete;
+#endif
 
 private:
   mpfr_t m_mpfr;


	Jakub