Re: [Qemu-devel] [PATCH v2] Makefile: Do not generate files if "configure" has not been run yet

[Eric Blake <eblake@redhat.com>]

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On 06/08/2017 02:40 AM, Thomas Huth wrote:
> When doing a "make -j10" in the vanilla QEMU source tree (without
> running "configure first), the Makefile currently generates two
> files already, qemu-version.h and qemu-options.def. This should not
> happen, so let's make these targets depend on config-host.mak.
> Also the targets that use python  can not be executed without the
> $(PYTHON) from config-host.mak, so these should depend on the config-
> host.mak file, too (these targets generate some ugly error messages
> otherwise during "make -j10").
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  v2:
>  - Add the dependency to the targets that use $(PYTHON) instead of
>    adding it to $(qapi-py)
> 
> @@ -312,6 +312,7 @@ qemu-version.h: FORCE
>  
>  config-host.h: config-host.h-timestamp
>  config-host.h-timestamp: config-host.mak
> +qemu-options.def: config-host.mak
>  qemu-options.def: $(SRC_PATH)/qemu-options.hx $(SRC_PATH)/scripts/hxtool
>  	$(call quiet-command,sh $(SRC_PATH)/scripts/hxtool -h < $< > $@,"GEN","$@")

This works (namely, splitting the dependencies between a no-op rule and
the real rule:

a:b
a:c
	recipe

), but looks unusual compared to having a single rule with all the
dependencies:

a: b c
	recipe

> @@ -394,17 +395,17 @@ gen-out-type = $(subst .,-,$(suffix $@))
>  qapi-py = $(SRC_PATH)/scripts/qapi.py $(SRC_PATH)/scripts/ordereddict.py
>  
>  qga/qapi-generated/qga-qapi-types.c qga/qapi-generated/qga-qapi-types.h :\
> -$(SRC_PATH)/qga/qapi-schema.json $(SRC_PATH)/scripts/qapi-types.py $(qapi-py)
> +$(SRC_PATH)/qga/qapi-schema.json $(SRC_PATH)/scripts/qapi-types.py $(qapi-py) config-host.mak
>  	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-types.py \

Long line. Let's use \ line-splitting to keep things under 80 columns
(if Fam's suggestion of adding the dependency just once doesn't pan out).

>  		$(gen-out-type) -o qga/qapi-generated -p "qga-" $<, \
>  		"GEN","$@")
>  qga/qapi-generated/qga-qapi-visit.c qga/qapi-generated/qga-qapi-visit.h :\
> -$(SRC_PATH)/qga/qapi-schema.json $(SRC_PATH)/scripts/qapi-visit.py $(qapi-py)
> +$(SRC_PATH)/qga/qapi-schema.json $(SRC_PATH)/scripts/qapi-visit.py $(qapi-py) config-host.mak

More long lines ahead.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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