bug#70410: Fwd: [PATCH] gotools: Workaround non-reproduceability of automake

[Eric Gallager]

GCC developers have recently found a source of non-determinism in
automake; this is bad for reproducible builds:

---------- Forwarded message ---------
From: Jakub Jelinek <jakub@redhat.com>
Date: Mon, Apr 15, 2024 at 8:43 AM
Subject: [PATCH] gotools: Workaround non-reproduceability of automake
To: Ian Lance Taylor <iant@golang.org>, Mark Wielaard <mjw@redhat.com>
Cc: <gcc-patches@gcc.gnu.org>


Hi!

The regen bot recently flagged a difference in gotools/Makefile.in.
Trying it locally, it seems pretty random
for i in `seq 20`; do
PATH=~/automake-1.15.1/bin:~/autoconf-2.69/bin:$PATH automake; echo -n
`git diff Makefile.in | wc -l`" "; done; echo; for i in `seq 20`; do
PATH=~/automake-1.15.1/bin:~/autoconf-2.69/bin:$PATH setarch x86_64 -R
automake; echo -n `git diff Makefile.in | wc -l`" "; done; echo;
14 14 14 0 0 0 14 0 14 0 14 14 14 14 0 14 14 0 0 0
14 0 14 0 0 14 14 14 0 14 14 0 0 14 14 14 0 0 0 14
The 14 line git diff is
diff --git a/gotools/Makefile.in b/gotools/Makefile.in
index 36c2ec2abd3..f40883c39be 100644
--- a/gotools/Makefile.in
+++ b/gotools/Makefile.in
@@ -704,8 +704,8 @@ distclean-generic:
 maintainer-clean-generic:
        @echo "This command is intended for maintainers to use"
        @echo "it deletes files that may require special tools to rebuild."
-@NATIVE_FALSE@install-exec-local:
 @NATIVE_FALSE@uninstall-local:
+@NATIVE_FALSE@install-exec-local:
 clean: clean-am

 clean-am: clean-binPROGRAMS clean-generic clean-noinstPROGRAMS \
so whether it is
@NATIVE_FALSE@install-exec-local:
@NATIVE_FALSE@uninstall-local:
or
@NATIVE_FALSE@uninstall-local:
@NATIVE_FALSE@install-exec-local:
depends on some hash table traversal or what.

I'm not familiar with automake/m4 enough to debug that, so I'm
instead offering a workaround, with this patch the order is deterministic.

2024-04-15  Jakub Jelinek  <jakub@redhat.com>

        * Makefile.am (install-exec-local, uninstall-local): Add goals
        on the else branch of if NATIVE to ensure reproducibility.
        * Makefile.in: Regenerate.

--- gotools/Makefile.am.jj      2023-11-04 09:02:35.802995614 +0100
+++ gotools/Makefile.am 2024-04-15 14:30:03.647171636 +0200
@@ -366,5 +366,7 @@ else
 # only do this if such a compiler is available.  We also need to get
 # the right values for GOARCH and GOOS in the default build context in
 # the go/build package.  Figure this out later.
+install-exec-local:
+uninstall-local:

 endif
--- gotools/Makefile.in.jj      2023-11-03 17:08:46.000439645 +0100
+++ gotools/Makefile.in 2024-04-15 14:31:32.270040117 +0200
@@ -704,8 +704,6 @@ distclean-generic:
 maintainer-clean-generic:
        @echo "This command is intended for maintainers to use"
        @echo "it deletes files that may require special tools to rebuild."
-@NATIVE_FALSE@install-exec-local:
-@NATIVE_FALSE@uninstall-local:
 clean: clean-am

 clean-am: clean-binPROGRAMS clean-generic clean-noinstPROGRAMS \
@@ -1035,6 +1033,8 @@ mostlyclean-local:
 # only do this if such a compiler is available.  We also need to get
 # the right values for GOARCH and GOOS in the default build context in
 # the go/build package.  Figure this out later.
+@NATIVE_FALSE@install-exec-local:
+@NATIVE_FALSE@uninstall-local:

 # Tell versions [3.59,3.63) of GNU make to not export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.

        Jakub