Add two small tooldir prefix patches to aid cross-compiling

14.2.0/gentoo/12_all_tooldir_prefix_lib.patch

@@ -0,0 +1,44 @@
+From 018edcc1c4649cccc86d9cb248efbc5ec9357293 Mon Sep 17 00:00:00 2001
+From: James Le Cuirot <[email protected]>
+Date: Thu, 2 Jan 2025 12:54:41 +0000
+Subject: [PATCH 1/3] Do not search for libs relative to the driver when
+ sysroot is changed
+
+When specifying a sysroot, the intention is to link against libraries in
+that sysroot rather than the toolchain's default sysroot. Having the
+toolchain default take priority is problematic, as libraries there may
+not be ABI compatible or may even have different sonames altogether.
+The desired sysroot is also not applied to ld scripts.
+
+Gentoo previously got away with this because only the toolchain's /lib
+was searched rather than /usr/lib, and the former did not contain many
+*.so files. Now that Gentoo is migrating cross environments to a
+merged-usr layout, these directories are the same, triggering the above
+issues much more frequently.
+
+In particular, the toolchain's /usr/lib/libc.so ld script is found
+before the sysroot's. This includes a reference to /lib/libc.so.6. The
+sysroot is only applied to this when the ld script itself is within that
+sysroot, so /lib/libc.so.6 is taken literally, causing the build
+machine's libc to be used instead, which immediately breaks any linking.
+
+Signed-off-by: James Le Cuirot <[email protected]>
+---
+ gcc/gcc.cc | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/gcc/gcc.cc b/gcc/gcc.cc
+index 728332b81..bef473939 100644
+--- a/gcc/gcc.cc
++++ b/gcc/gcc.cc
+@@ -5496,6 +5496,7 @@ process_command (unsigned int decoded_options_count,
+   add_prefix (&exec_prefixes,
+ 	      concat (tooldir_prefix, "bin", dir_separator_str, NULL),
+ 	      "BINUTILS", PREFIX_PRIORITY_LAST, 0, 0);
++  if (!target_system_root_changed)
+   add_prefix (&startfile_prefixes,
+ 	      concat (tooldir_prefix, "lib", dir_separator_str, NULL),
+ 	      "BINUTILS", PREFIX_PRIORITY_LAST, 0, 1);
+-- 
+2.47.1
+

14.2.0/gentoo/13_all_tooldir_prefix_bin.patch

@@ -0,0 +1,35 @@
+From 886520dcf2a59105cc78573f4c5a5cb34ad05579 Mon Sep 17 00:00:00 2001
+From: James Le Cuirot <[email protected]>
+Date: Thu, 2 Jan 2025 12:46:55 +0000
+Subject: [PATCH 2/3] Do not search for tools relative to the driver when
+ cross-compiling
+
+On Gentoo, this location is /usr/${CHOST}/bin. Native toolchains put
+symlinks to the binutils tools here. Cross toolchains only put
+non-native binaries here. The binutils symlinks live under
+/usr/libexec/gcc/${CHOST} instead, and that location is already
+searched.
+
+It would be better to fail to find a given tool than inadvertently try
+to execute a non-native build of it via QEMU.
+
+Signed-off-by: James Le Cuirot <[email protected]>
+---
+ gcc/gcc.cc | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/gcc/gcc.cc b/gcc/gcc.cc
+index bef473939..20044bc3a 100644
+--- a/gcc/gcc.cc
++++ b/gcc/gcc.cc
+@@ -5493,6 +5493,7 @@ process_command (unsigned int decoded_options_count,
+ 	      accel_dir_suffix, dir_separator_str, tooldir_prefix2, NULL);
+   free (tooldir_prefix2);
+
++  if (*cross_compile == '0')
+   add_prefix (&exec_prefixes,
+ 	      concat (tooldir_prefix, "bin", dir_separator_str, NULL),
+ 	      "BINUTILS", PREFIX_PRIORITY_LAST, 0, 0);
+-- 
+2.47.1
+

14.2.0/gentoo/README.history

@@ -1,3 +1,8 @@
+8	????
+
+	+ 12_all_tooldir_prefix_lib.patch
+	+ 13_all_tooldir_prefix_bin.patch
+
 7	24 Dec 2024
 
 	U 70_all_PR117854-config-nvptx-fix-bashisms-with-gen-copyright.sh-use.patch

15.0.0/gentoo/12_all_tooldir_prefix_lib.patch

@@ -0,0 +1,44 @@
+From dc817f621aa5a99ce05d9336aa8ef57835fc009b Mon Sep 17 00:00:00 2001
+From: James Le Cuirot <[email protected]>
+Date: Thu, 2 Jan 2025 12:54:41 +0000
+Subject: [PATCH 1/3] Do not search for libs relative to the driver when
+ sysroot is changed
+
+When specifying a sysroot, the intention is to link against libraries in
+that sysroot rather than the toolchain's default sysroot. Having the
+toolchain default take priority is problematic, as libraries there may
+not be ABI compatible or may even have different sonames altogether.
+The desired sysroot is also not applied to ld scripts.
+
+Gentoo previously got away with this because only the toolchain's /lib
+was searched rather than /usr/lib, and the former did not contain many
+*.so files. Now that Gentoo is migrating cross environments to a
+merged-usr layout, these directories are the same, triggering the above
+issues much more frequently.
+
+In particular, the toolchain's /usr/lib/libc.so ld script is found
+before the sysroot's. This includes a reference to /lib/libc.so.6. The
+sysroot is only applied to this when the ld script itself is within that
+sysroot, so /lib/libc.so.6 is taken literally, causing the build
+machine's libc to be used instead, which immediately breaks any linking.
+
+Signed-off-by: James Le Cuirot <[email protected]>
+---
+ gcc/gcc.cc | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/gcc/gcc.cc b/gcc/gcc.cc
+index 95b98eaa8..210991153 100644
+--- a/gcc/gcc.cc
++++ b/gcc/gcc.cc
+@@ -5522,6 +5522,7 @@ process_command (unsigned int decoded_options_count,
+   add_prefix (&exec_prefixes,
+ 	      concat (tooldir_prefix, "bin", dir_separator_str, NULL),
+ 	      "BINUTILS", PREFIX_PRIORITY_LAST, 0, 0);
++  if (!target_system_root_changed)
+   add_prefix (&startfile_prefixes,
+ 	      concat (tooldir_prefix, "lib", dir_separator_str, NULL),
+ 	      "BINUTILS", PREFIX_PRIORITY_LAST, 0, 1);
+-- 
+2.47.1
+

15.0.0/gentoo/13_all_tooldir_prefix_bin.patch

@@ -0,0 +1,35 @@
+From cef4c8559cf0a3523d5ff0ae91e56ea6652456c7 Mon Sep 17 00:00:00 2001
+From: James Le Cuirot <[email protected]>
+Date: Thu, 2 Jan 2025 12:46:55 +0000
+Subject: [PATCH 2/3] Do not search for tools relative to the driver when
+ cross-compiling
+
+On Gentoo, this location is /usr/${CHOST}/bin. Native toolchains put
+symlinks to the binutils tools here. Cross toolchains only put
+non-native binaries here. The binutils symlinks live under
+/usr/libexec/gcc/${CHOST} instead, and that location is already
+searched.
+
+It would be better to fail to find a given tool than inadvertently try
+to execute a non-native build of it via QEMU.
+
+Signed-off-by: James Le Cuirot <[email protected]>
+---
+ gcc/gcc.cc | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/gcc/gcc.cc b/gcc/gcc.cc
+index 210991153..4188f0049 100644
+--- a/gcc/gcc.cc
++++ b/gcc/gcc.cc
+@@ -5519,6 +5519,7 @@ process_command (unsigned int decoded_options_count,
+ 	      accel_dir_suffix, dir_separator_str, tooldir_prefix2, NULL);
+   free (tooldir_prefix2);
+
++  if (*cross_compile == '0')
+   add_prefix (&exec_prefixes,
+ 	      concat (tooldir_prefix, "bin", dir_separator_str, NULL),
+ 	      "BINUTILS", PREFIX_PRIORITY_LAST, 0, 0);
+-- 
+2.47.1
+

15.0.0/gentoo/README.history

@@ -1,6 +1,8 @@
 36	????
 
 	- 73_all_PR117629-c-special-case-some-bool-errors-with-C23.patch
+	+ 12_all_tooldir_prefix_lib.patch
+	+ 13_all_tooldir_prefix_bin.patch
 
 35	30 December 2024