[Buildroot] [PATCH 2/2] linux: fix build with host-gcc 10+

["Yann E. MORIN" <yann.morin.1998@free.fr>]

Some older versions of linux, or custom versions (like forks for some
boards), fail to build with host-gcc 10+, because of redefined symbols:

      HOSTLD  scripts/dtc/dtc
    /usr/bin/ld: scripts/dtc/dtc-parser.tab.o:(.bss+0x10): multiple definition
    of `yylloc'; scripts/dtc/dtc-lexer.lex.o:(.bss+0x0): first defined here
    collect2: error: ld returned 1 exit status

Since this has been fixed in recent-ish versions, we can't use an
unconditionaly patch, so we must have a conditional patch. However, a
patch may not always apply to arbitrary U-Boot versions or forks.

Upstream just dropped that line altogether:
    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e33a814e772cdc36436c8c188d8c42d019fda639

So, we use a little sed-grep combo to do the exact same change.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
---
 linux/linux.mk | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/linux/linux.mk b/linux/linux.mk
index dd2eebd446..2a841ca3e6 100644
--- a/linux/linux.mk
+++ b/linux/linux.mk
@@ -268,6 +268,12 @@ endef
 
 LINUX_POST_PATCH_HOOKS += LINUX_APPLY_LOCAL_PATCHES
 
+# Older versions break on gcc 10+ because of redefined symbols
+define LINUX_DROP_YYLLOC
+	$(SED) '/^YYLTYPE yylloc;$$/d' `grep -l -r -E '^YYLTYPE yylloc;$$' $(@D)`
+endef
+LINUX_POST_PATCH_HOOKS += LINUX_DROP_YYLLOC
+
 # Older linux kernels use deprecated perl constructs in timeconst.pl
 # that were removed for perl 5.22+ so it breaks on newer distributions
 # Try a dry-run patch to see if this applies, if it does go ahead
-- 
2.25.1

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