Re: [PATCH] btrfs: Use immediate assignment when referencing cc-option
From: David Sterba <hidden>
Date: 2021-03-17 08:42:10
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lkml
On Tue, Mar 16, 2021 at 03:46:10PM -0700, Victor Erminpour wrote:
quoted hunk ↗ jump to hunk
Calling cc-option will use KBUILD_CFLAGS, which when lazy setting subdir-ccflags-y produces the following build error: scripts/Makefile.lib:10: *** Recursive variable `KBUILD_CFLAGS' \ references itself (eventually). Stop. Use := assignment to subdir-ccflags-y when referencing cc-option. This causes make to also evaluate += immediately, cc-option calls are done right away and we don't end up with KBUILD_CFLAGS referencing itself. Signed-off-by: Victor Erminpour <redacted> --- fs/btrfs/Makefile | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile index b634c42115ea..3dba1336fa95 100644 --- a/fs/btrfs/Makefile +++ b/fs/btrfs/Makefile@@ -7,10 +7,10 @@ subdir-ccflags-y += -Wmissing-format-attribute subdir-ccflags-y += -Wmissing-prototypes subdir-ccflags-y += -Wold-style-definition subdir-ccflags-y += -Wmissing-include-dirs -subdir-ccflags-y += $(call cc-option, -Wunused-but-set-variable) -subdir-ccflags-y += $(call cc-option, -Wunused-const-variable) -subdir-ccflags-y += $(call cc-option, -Wpacked-not-aligned) -subdir-ccflags-y += $(call cc-option, -Wstringop-truncation) +subdir-ccflags-y := $(call cc-option, -Wunused-but-set-variable) +subdir-ccflags-y := $(call cc-option, -Wunused-const-variable) +subdir-ccflags-y := $(call cc-option, -Wpacked-not-aligned) +subdir-ccflags-y := $(call cc-option, -Wstringop-truncation)
But this overwrites all the previously accumulated values from += so effectively there's only the last one, no? That's not what we want.