From 364713fdd33de8ea0accfbf9f9cf342abaac2b62 Mon Sep 17 00:00:00 2001
From: sternenseemann <0rpkxez4ksa01gb3typccl0i@systemli.org>
Date: Thu, 22 Jul 2021 18:57:58 +0200
Subject: [PATCH] gnat*: bootstrap cross with native compiler of the same
 version

https://gcc.gnu.org/install/prerequisites.html#GNAT-prerequisite
---
 pkgs/top-level/all-packages.nix | 37 +++++++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 7dc2993f453d..c5a3949c805a 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -11212,7 +11212,15 @@ in
     langCC = false;
     langAda = true;
     profiledCompiler = false;
-    inherit (buildPackages) gnatboot;
+    # As per upstream instructions building a cross compiler
+    # should be done with a (native) compiler of the same version.
+    # If we are cross-compiling GNAT, we may as well go the same
+    # route (especially as gnatboot can't cross-compile).
+    gnatboot =
+      if stdenv.hostPlatform == stdenv.targetPlatform
+         && stdenv.buildPlatform == stdenv.hostPlatform
+      then buildPackages.gnatboot
+      else buildPackages.gnat6;
   });
 
   gnat9 = wrapCC (gcc9.cc.override {
@@ -11221,7 +11229,14 @@ in
     langCC = false;
     langAda = true;
     profiledCompiler = false;
-    gnatboot = buildPackages.gnat6;
+    # As per upstream instructions building a cross compiler
+    # should be done with a (native) compiler of the same version.
+    # If we are cross-compiling GNAT, we may as well do the same.
+    gnatboot =
+      if stdenv.hostPlatform == stdenv.targetPlatform
+         && stdenv.buildPlatform == stdenv.hostPlatform
+      then buildPackages.gnat6
+      else buildPackages.gnat9;
   });
 
   gnat10 = wrapCC (gcc10.cc.override {
@@ -11230,7 +11245,14 @@ in
     langCC = false;
     langAda = true;
     profiledCompiler = false;
-    gnatboot = buildPackages.gnat6;
+    # As per upstream instructions building a cross compiler
+    # should be done with a (native) compiler of the same version.
+    # If we are cross-compiling GNAT, we may as well do the same.
+    gnatboot =
+      if stdenv.hostPlatform == stdenv.targetPlatform
+         && stdenv.buildPlatform == stdenv.hostPlatform
+      then buildPackages.gnat6
+      else buildPackages.gnat10;
   });
 
   gnat11 = wrapCC (gcc11.cc.override {
@@ -11239,7 +11261,14 @@ in
     langCC = false;
     langAda = true;
     profiledCompiler = false;
-    gnatboot = buildPackages.gnat6;
+    # As per upstream instructions building a cross compiler
+    # should be done with a (native) compiler of the same version.
+    # If we are cross-compiling GNAT, we may as well do the same.
+    gnatboot =
+      if stdenv.hostPlatform == stdenv.targetPlatform
+         && stdenv.buildPlatform == stdenv.hostPlatform
+      then buildPackages.gnat6
+      else buildPackages.gnat11;
   });
 
   gnatboot = wrapCC (callPackage ../development/compilers/gnatboot { });