package/gcc/9.3.0: fix host-gcc-final when ccache is used

As reported by several Buildroot users [1][2][3], the gcc build
may fail while running selftests makefile target.

The problem only occurs when ccache is used with gcc 9 and 10,
probably due to a race condition.

While debuging with "make -p" we can notice that s-selftest-c target
contain only "cc1" as dependency instead of cc1 and SELFTEST_DEPS [4].

  s-selftest-c: cc1

While the build is failing, the s-selftest-c dependencies recipe is
still running and reported as a bug by make.

  "Dependencies recipe running (THIS IS A BUG)."

A change [5] in gcc 9 seems to introduce the problem since we can't
reproduce this problem with gcc 8.

As suggested by Yann E. MORIN [6], move SELFTEST_DEPS before
including language makefile fragments.

With the fix applied, the s-seltest-c dependency contains
SELFTEST_DEPS value.

  s-selftest-c: cc1 xgcc specs stmp-int-hdrs ../../gcc/testsuite/selftests

[1] http://lists.busybox.net/pipermail/buildroot/2020-May/282171.html
[2] http://lists.busybox.net/pipermail/buildroot/2020-May/282766.html
[3] cirosantilli/linux-kernel-module-cheat#108
[4] https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/c/Make-lang.in;h=bfae6fd2549c4f728816cd355fa9739dcc08fcde;hb=033eb5671769a4c681a44aad08a454e667e08502#l120
[5] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=033eb5671769a4c681a44aad08a454e667e08502
[6] http://lists.busybox.net/pipermail/buildroot/2020-May/283213.html

Signed-off-by: Romain Naour <[email protected]>
Cc: Ben Dakin-Norris <[email protected]>
Cc: Maxim Kochetkov <[email protected]>
Cc: Thomas Petazzoni <[email protected]>
Cc: Yann E. MORIN <[email protected]>
Signed-off-by: Yann E. MORIN <[email protected]>
(cherry picked from commit 58ecbbc)
Signed-off-by: Peter Korsgaard <[email protected]>

Author: RomainNaour

package/gcc/9.2.0/0004-gcc-Makefile.in-move-SELFTEST_DEPS-before-including-.patch

@@ -0,0 +1,81 @@
+From 811c8d628045c3d248144fc560a4bf80209ca16e Mon Sep 17 00:00:00 2001
+From: Romain Naour <[email protected]>
+Date: Thu, 21 May 2020 15:58:02 +0200
+Subject: [PATCH] gcc/Makefile.in: move SELFTEST_DEPS before including language
+ makefile fragments
+
+As reported by several Buildroot users [1][2][3], the gcc build
+may fail while running selftests makefile target.
+
+The problem only occurs when ccache is used with gcc 9 and 10,
+probably due to a race condition.
+
+While debuging with "make -p" we can notice that s-selftest-c target
+contain only "cc1" as dependency instead of cc1 and SELFTEST_DEPS [4].
+
+  s-selftest-c: cc1
+
+While the build is failing, the s-selftest-c dependencies recipe is
+still running and reported as a bug by make.
+
+  "Dependencies recipe running (THIS IS A BUG)."
+
+A change [5] in gcc 9 seems to introduce the problem since we can't
+reproduce this problem with gcc 8.
+
+As suggested by Yann E. MORIN [6], move SELFTEST_DEPS before
+including language makefile fragments.
+
+With the fix applied, the s-seltest-c dependency contains
+SELFTEST_DEPS value.
+
+  s-selftest-c: cc1 xgcc specs stmp-int-hdrs ../../gcc/testsuite/selftests
+
+[1] http://lists.busybox.net/pipermail/buildroot/2020-May/282171.html
+[2] http://lists.busybox.net/pipermail/buildroot/2020-May/282766.html
+[3] https://github.com/cirosantilli/linux-kernel-module-cheat/issues/108
+[4] https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/c/Make-lang.in;h=bfae6fd2549c4f728816cd355fa9739dcc08fcde;hb=033eb5671769a4c681a44aad08a454e667e08502#l120
+[5] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=033eb5671769a4c681a44aad08a454e667e08502
+[6] http://lists.busybox.net/pipermail/buildroot/2020-May/283213.html
+
+Upstream status: https://gcc.gnu.org/pipermail/gcc-patches/2020-May/546248.html
+
+Signed-off-by: Romain Naour <[email protected]>
+Cc: Ben Dakin-Norris <[email protected]>
+Cc: Maxim Kochetkov <[email protected]>
+Cc: Thomas Petazzoni <[email protected]>
+Cc: Yann E. MORIN <[email protected]>
+Cc: Cc: David Malcolm <[email protected]>
+---
+This patch should be backported to gcc 10 and gcc 9.
+---
+ gcc/Makefile.in | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/gcc/Makefile.in b/gcc/Makefile.in
+index abae872cd63..e2ef3c46afc 100644
+--- a/gcc/Makefile.in
++++ b/gcc/Makefile.in
+@@ -1686,6 +1686,10 @@ $(FULL_DRIVER_NAME): ./xgcc
+ 	rm -f $@
+ 	$(LN_S) $< $@
+ 
++# SELFTEST_DEPS need to be set before including language makefile fragments.
++# Otherwise $(SELFTEST_DEPS) is empty when used from various <LANG>/Make-lang.in.
++SELFTEST_DEPS = $(GCC_PASSES) stmp-int-hdrs $(srcdir)/testsuite/selftests
++
+ #
+ # Language makefile fragments.
+ 
+@@ -1950,8 +1954,6 @@ DEVNULL=$(if $(findstring mingw,$(build)),nul,/dev/null)
+ SELFTEST_FLAGS = -nostdinc $(DEVNULL) -S -o $(DEVNULL) \
+ 	-fself-test=$(srcdir)/testsuite/selftests
+ 
+-SELFTEST_DEPS = $(GCC_PASSES) stmp-int-hdrs $(srcdir)/testsuite/selftests
+-
+ # Run the selftests during the build once we have a driver and the frontend,
+ # so that self-test failures are caught as early as possible.
+ # Use "s-selftest-FE" to ensure that we only run the selftests if the
+-- 
+2.25.4
+