On Fri, Jun 16, 2023 at 11:57:50PM +0900, Masahiro Yamada wrote:
> With commit 9da0763bdd82 ("kbuild: Use relative path when building in
> a subdir of the source tree"), compiler messages in out-of-tree builds
> include relative paths, which are relative to the build directory, not
> the directory where make was started.
>
> To help IDEs/editors find the source files, Kbuild lets GNU Make print
> "Entering directory ..." when it changes the working directory. It has
> been working fine for a long time, but David reported it is broken with
> the latest GNU Make.
>
> The behavior was changed by GNU Make commit 8f9e7722ff0f ("[SV 63537]
> Fix setting -w in makefiles"). Previously, setting --no-print-directory
> to MAKEFLAGS only affected child makes, but it is now interpreted in
> the current make as soon as it is set.
>
> [test code]
>
> $ cat /tmp/Makefile
> ifneq ($(SUBMAKE),1)
> MAKEFLAGS += --no-print-directory
> all: ; $(MAKE) SUBMAKE=1
> else
> all: ; :
> endif
>
> [before 8f9e7722ff0f]
>
> $ make -C /tmp
> make: Entering directory '/tmp'
> make SUBMAKE=1
> :
> make: Leaving directory '/tmp'
>
> [after 8f9e7722ff0f]
>
> $ make -C /tmp
> make SUBMAKE=1
> :
>
> Previously, the effect of --no-print-directory was delayed until Kbuild
> started the directory descending, but it is no longer true with GNU Make
> 4.4.1.
>
> This commit adds one more recursion to cater to GNU Make >= 4.4.1.
>
> When Kbuild needs to change the working directory, __submake will be
> executed twice.
>
> __submake without --no-print-directory --> show "Entering directory ..."
> __submake with --no-print-directory --> parse the rest of Makefile
>
> We end up with one more recursion than needed for GNU Make < 4.4.1, but
> I do not want to complicate the version check.
>
> Reported-by: David Howells <dhowells@xxxxxxxxxx>
> Closes: https://lore.kernel.org/all/2427604.1686237298@xxxxxxxxxxxxxxxxxxxxxx/
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> ---
>
> Changes in v2:
> - Fix the code. V1 did not work.
> - Remove the version check to simplify the code
Tested-by: Nicolas Schier <n.schier@xxxxxx>
>
> Makefile | 36 ++++++++++++++++++++----------------
> 1 file changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index cc3fe09c4dec..916c1a7984b0 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -189,13 +189,6 @@ else
> abs_objtree := $(CURDIR)
> endif # ifneq ($(KBUILD_OUTPUT),)
>
> -ifeq ($(abs_objtree),$(CURDIR))
> -# Suppress "Entering directory ..." unless we are changing the work directory.
> -MAKEFLAGS += --no-print-directory
> -else
> -need-sub-make := 1
> -endif
> -
> this-makefile := $(lastword $(MAKEFILE_LIST))
> abs_srctree := $(realpath $(dir $(this-makefile)))
>
> @@ -214,6 +207,23 @@ endif
> export abs_srctree abs_objtree
> export sub_make_done := 1
>
> +endif # sub_make_done
> +
> +ifeq ($(abs_objtree),$(CURDIR))
> +# Suppress "Entering directory ..." if we are at the final work directory.
> +no-print-directory := --no-print-directory
> +else
> +# Recursion to show "Entering directory ..."
> +need-sub-make := 1
> +endif
> +
> +ifeq ($(filter --no-print-directory, $(MAKEFLAGS)),)
> +# If --no-print-directory is unset, recurse once again to set it.
> +# You may end up with recursing into __sub-make twice. This is due to the
> +# behavior change for GNU Make 4.4.1.
> +need-sub-make := 1
> +endif
> +
> ifeq ($(need-sub-make),1)
>
> PHONY += $(MAKECMDGOALS) __sub-make
> @@ -223,18 +233,12 @@ $(filter-out $(this-makefile), $(MAKECMDGOALS)) __all: __sub-make
>
> # Invoke a second make in the output directory, passing relevant variables
> __sub-make:
> - $(Q)$(MAKE) -C $(abs_objtree) -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
> + $(Q)$(MAKE) $(no-print-directory) -C $(abs_objtree) \
> + -f $(abs_srctree)/Makefile $(MAKECMDGOALS)
>
> -endif # need-sub-make
> -endif # sub_make_done
> +else # need-sub-make
>
> # We process the rest of the Makefile if this is the final invocation of make
> -ifeq ($(need-sub-make),)
> -
> -# Do not print "Entering directory ...",
> -# but we want to display it when entering to the output directory
> -# so that IDEs/editors are able to understand relative filenames.
> -MAKEFLAGS += --no-print-directory
>
> ifeq ($(abs_srctree),$(abs_objtree))
> # building in the source tree
> --
> 2.39.2
>
