2021-03-17 17:21:09

by Victor Erminpour

Subject: [PATCH v2] btrfs: Use immediate assignment when referencing cc-option

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 single := assignment for subdir-ccflags-y. The cc-option calls
are done right away and we don't end up with KBUILD_CFLAGS
referencing itself.

Signed-off-by: Victor Erminpour <[email protected]>
---
fs/btrfs/Makefile | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index b634c42115ea..583ca2028e08 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -1,16 +1,16 @@
# SPDX-License-Identifier: GPL-2.0

# Subset of W=1 warnings
+subdir-ccflags-y := $(call cc-option, -Wunused-but-set-variable) \
+ $(call cc-option, -Wunused-const-variable) \
+ $(call cc-option, -Wpacked-not-aligned) \
+ $(call cc-option, -Wstringop-truncation)
subdir-ccflags-y += -Wextra -Wunused -Wno-unused-parameter
subdir-ccflags-y += -Wmissing-declarations
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)
# The following turn off the warnings enabled by -Wextra
subdir-ccflags-y += -Wno-missing-field-initializers
subdir-ccflags-y += -Wno-sign-compare

2021-03-17 17:25:48

by David Sterba

Subject: Re: [PATCH v2] btrfs: Use immediate assignment when referencing cc-option

On Wed, Mar 17, 2021 at 09:08:48AM -0700, Victor Erminpour wrote:
> 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 single := assignment for subdir-ccflags-y. The cc-option calls
> are done right away and we don't end up with KBUILD_CFLAGS
> referencing itself.
>
> Signed-off-by: Victor Erminpour <[email protected]>
> ---
> fs/btrfs/Makefile | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
> index b634c42115ea..583ca2028e08 100644
> --- a/fs/btrfs/Makefile
> +++ b/fs/btrfs/Makefile
> @@ -1,16 +1,16 @@
> # SPDX-License-Identifier: GPL-2.0
>
> # Subset of W=1 warnings
> +subdir-ccflags-y := $(call cc-option, -Wunused-but-set-variable) \
> + $(call cc-option, -Wunused-const-variable) \
> + $(call cc-option, -Wpacked-not-aligned) \
> + $(call cc-option, -Wstringop-truncation)

That's still overwriting the value unconditionally, the idea was a
separate variable

https://lore.kernel.org/linux-btrfs/[email protected]