[Buildroot] [PATCHv2] meson: add per package optional compiler/linker flags

[Buildroot] [PATCHv2] meson: add per package optional compiler/linker flags

[Yann E. MORIN]

From: Peter Seiderer <ps.report@gmx.net>

Add LIBFOO_CFLAGS, LIBFOO_LDFLAGS and LIBFOO_CXXFLAGS variables to allow
packages to provide their own flags, possibly overriding the generic
ones entirely, like we allow for other infras.

This means that the meson infra is the first and only infra for which
FOO_CFLAGS, FOO_LDFLAGS, and FOOO_CXXFLAGS are meaningful, while for the
other infras, they are just variable private to the package itself.
Instead of naming those variables after the meson infra (e.g.
LIBFOO_MESON_CFLAGS), we name them with a generic name, as mayb, just
maybe, we could also change the ither infras to also recognise those
variables.

To mimic this feature for packages that are bui9lt from the SDK, we also
install a templatised version of cross-compilation.conf, with three new
placeholders for custom flags. If a user wants to buidl a package that
needs custom flags, they can use that template to generate a per-pacakge
cross-compilation.conf.

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Adam Duskett <aduskett@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

---
Changes v1 -> v2 (adopted by Yann):
  - rename the variables
  - don't add new placeholders in the bundled template; instead, insert
    those placeholders when generating the partially-templatised
    template (irk!).
  - update the doc
---
 docs/manual/adding-packages-meson.txt | 12 ++++++++++++
 package/meson/meson.mk                | 14 ++++++++++----
 package/pkg-meson.mk                  | 14 +++++++++++---
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/docs/manual/adding-packages-meson.txt b/docs/manual/adding-packages-meson.txt
index 30c338f486..c0bfa6a13f 100644
--- a/docs/manual/adding-packages-meson.txt
+++ b/docs/manual/adding-packages-meson.txt
@@ -97,6 +97,18 @@ will therefore only use a few of them.
 * +FOO_CONF_OPTS+, to specify additional options to pass to +meson+ for the
   configuration step. By default, empty.
 
+* +FOO_CFLAGS+, to specify compiler arguments added to the package specific
+  +cross-compile.conf+ file +c_args+ property. By default, empty, so that
+  the global +TARGET_CFLAGS+ are used.
+
+* +FOO_CXXFLAGS+, to specify compiler arguments added to the package specific
+  +cross-compile.conf+ file +cpp_args+ property. By default, empty, so that
+  the global +TARGET_CXXFLAGS+ are used.
+
+* +FOO_LDFLAGS+, to specify compiler arguments added to the package specific
+  +cross-compile.conf+ file +c_link_args+ and +cpp_link_args+ properties. By
+  default, empty, so that the global +TARGET_LDFLAGS+ are used.
+
 * +FOO_NINJA_ENV+, to specify additional environment variables to pass to
   +ninja+, meson companion tool in charge of the build operations. By default,
   empty.
diff --git a/package/meson/meson.mk b/package/meson/meson.mk
index 5b5100cccc..c9269d2a7c 100644
--- a/package/meson/meson.mk
+++ b/package/meson/meson.mk
@@ -50,18 +50,24 @@ HOST_MESON_SED_LDFLAGS = $(if $(TARGET_LDFLAGS),`printf '"%s"$(comma) ' $(TARGET
 HOST_MESON_SED_CXXFLAGS = $(if $(TARGET_CXXFLAGS),`printf '"%s"$(comma) ' $(TARGET_CXXFLAGS)`)
 
 # Generate a Meson cross-compilation.conf suitable for use with the
-# SDK
+# SDK; also install the file as a template for users to add their
+# own flags if they need to.
 define HOST_MESON_INSTALL_CROSS_CONF
 	mkdir -p $(HOST_DIR)/etc/meson
 	sed -e "s%@TARGET_CROSS@%$(TARGET_CROSS)%g" \
 	    -e "s%@TARGET_ARCH@%$(HOST_MESON_TARGET_CPU_FAMILY)%g" \
 	    -e "s%@TARGET_CPU@%$(HOST_MESON_TARGET_CPU)%g" \
 	    -e "s%@TARGET_ENDIAN@%$(HOST_MESON_TARGET_ENDIAN)%g" \
-	    -e "s%@TARGET_CFLAGS@%$(HOST_MESON_SED_CFLAGS)%g" \
-	    -e "s%@TARGET_LDFLAGS@%$(HOST_MESON_SED_LDFLAGS)%g" \
-	    -e "s%@TARGET_CXXFLAGS@%$(HOST_MESON_SED_CXXFLAGS)%g" \
+	    -e "s%@TARGET_CFLAGS@%$(HOST_MESON_SED_CFLAGS)@PKG_TARGET_CFLAGS@%g" \
+	    -e "s%@TARGET_LDFLAGS@%$(HOST_MESON_SED_LDFLAGS)@PKG_TARGET_CFLAGS@%g" \
+	    -e "s%@TARGET_CXXFLAGS@%$(HOST_MESON_SED_CXXFLAGS)@PKG_TARGET_CFLAGS@%g" \
 	    -e "s%@HOST_DIR@%$(HOST_DIR)%g" \
 	    $(HOST_MESON_PKGDIR)/cross-compilation.conf.in \
+	    > $(HOST_DIR)/etc/meson/cross-compilation.conf.in
+	sed -e "s%@PKG_TARGET_CFLAGS@%%g" \
+	    -e "s%@PKG_TARGET_LDFLAGS@%%g" \
+	    -e "s%@PKG_TARGET_CXXFLAGS@%%g" \
+	    $(HOST_DIR)/etc/meson/cross-compilation.conf.in \
 	    > $(HOST_DIR)/etc/meson/cross-compilation.conf
 endef
 
diff --git a/package/pkg-meson.mk b/package/pkg-meson.mk
index 886fcf7205..807b578219 100644
--- a/package/pkg-meson.mk
+++ b/package/pkg-meson.mk
@@ -57,6 +57,14 @@ $(2)_NINJA_ENV		?=
 ifndef $(2)_CONFIGURE_CMDS
 ifeq ($(4),target)
 
+$(2)_CFLAGS ?= $$(TARGET_CFLAGS)
+$(2)_LDFLAGS ?= $$(TARGET_LDFLAGS)
+$(2)_CXXFLAGS ?= $$(TARGET_CXXFLAGS)
+
+$(2)_MESON_SED_CFLAGS = $(if $($(2)_CFLAGS),`printf '"%s"$$(comma) ' $($(2)_CFLAGS)`)
+$(2)_MESON_SED_LDFLAGS = $(if $($(2)_LDFLAGS),`printf '"%s"$$(comma) ' $($(2)_LDFLAGS)`)
+$(2)_MESON_SED_CXXFLAGS = $(if $($(2)_CXXFLAGS),`printf '"%s"$$(comma) ' $$($$(2)_CXXFLAGS)`)
+
 # Configure package for target
 #
 #
@@ -67,9 +75,9 @@ define $(2)_CONFIGURE_CMDS
 	    -e "s%@TARGET_ARCH@%$$(HOST_MESON_TARGET_CPU_FAMILY)%g" \
 	    -e "s%@TARGET_CPU@%$$(GCC_TARGET_CPU)%g" \
 	    -e "s%@TARGET_ENDIAN@%$$(call LOWERCASE,$$(BR2_ENDIAN))%g" \
-	    -e "s%@TARGET_CFLAGS@%$$(HOST_MESON_SED_CFLAGS)%g" \
-	    -e "s%@TARGET_LDFLAGS@%$$(HOST_MESON_SED_LDFLAGS)%g" \
-	    -e "s%@TARGET_CXXFLAGS@%$$(HOST_MESON_SED_CXXFLAGS)%g" \
+	    -e "s%@TARGET_CFLAGS@%$$($(2)_MESON_SED_CFLAGS)%g" \
+	    -e "s%@TARGET_LDFLAGS@%$$($(2)_MESON_SED_LDFLAGS)%g" \
+	    -e "s%@TARGET_CXXFLAGS@%$$($(2)_MESON_SED_CXXFLAGS)%g" \
 	    -e "s%@HOST_DIR@%$$(HOST_DIR)%g" \
 	    package/meson/cross-compilation.conf.in \
 	    > $$($$(PKG)_SRCDIR)/build/cross-compilation.conf
-- 
2.20.1

[Buildroot] [PATCHv2] meson: add per package optional compiler/linker flags

[Thomas Petazzoni]

Hello Yann,

Thanks for respining. One question below.

On Sat, 22 Jun 2019 22:20:46 +0200
"Yann E. MORIN" <yann.morin.1998@free.fr> wrote:

Perhaps the commit should explain that as of today, Meson doesn't allow
to pass cflags/ldflags on the command line when a cross-compilation
file is used.

> Add LIBFOO_CFLAGS, LIBFOO_LDFLAGS and LIBFOO_CXXFLAGS variables to allow
> packages to provide their own flags, possibly overriding the generic
> ones entirely, like we allow for other infras.
> 
> This means that the meson infra is the first and only infra for which
> FOO_CFLAGS, FOO_LDFLAGS, and FOOO_CXXFLAGS are meaningful, while for the
> other infras, they are just variable private to the package itself.
> Instead of naming those variables after the meson infra (e.g.
> LIBFOO_MESON_CFLAGS), we name them with a generic name, as mayb, just

mayb -> maybe

> maybe, we could also change the ither infras to also recognise those

ither -> other

> variables.
> 
> To mimic this feature for packages that are bui9lt from the SDK, we also

built

> install a templatised version of cross-compilation.conf, with three new
> placeholders for custom flags. If a user wants to buidl a package that

build

> needs custom flags, they can use that template to generate a per-pacakge

package

> +* +FOO_CFLAGS+, to specify compiler arguments added to the package specific
> +  +cross-compile.conf+ file +c_args+ property. By default, empty, so that
> +  the global +TARGET_CFLAGS+ are used.

I find the wording "By default, empty, so that the global
+TARGET_CFLAGS+ are used" very confusing. Indeed, by default, those
variables are not empty, they are precisely defined to TARGET_CFLAGS.

For example, in the autotools infra documentation, we say:

* +LIBFOO_AUTORECONF+, tells whether the package should
  be autoreconfigured or not (i.e. if the configure script and
  Makefile.in files should be re-generated by re-running autoconf,
  automake, libtool, etc.). Valid values are +YES+ and
  +NO+. By default, the value is +NO+

So we just say that the default value is NO, not that it is empty and
that NO is used :)

For extra clarity, it could be rephrased like this:

	When no value is specified by the package for this variable,
	the value of +TARGET_CFLAGS+ will be used by the
	+meson-package+ infrastructure.

If you agree with this change, I can fix that up when applying.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[Buildroot] [PATCHv2] meson: add per package optional compiler/linker flags

[Yann E. MORIN]

Thomas, All,

On 2019-06-23 12:36 +0200, Thomas Petazzoni spake thusly:
> On Sat, 22 Jun 2019 22:20:46 +0200
> "Yann E. MORIN" <yann.morin.1998@free.fr> wrote:
> 
> Perhaps the commit should explain that as of today, Meson doesn't allow
> to pass cflags/ldflags on the command line when a cross-compilation
> file is used.

Indeed.

[--SNIP--]
> > +* +FOO_CFLAGS+, to specify compiler arguments added to the package specific
> > +  +cross-compile.conf+ file +c_args+ property. By default, empty, so that
> > +  the global +TARGET_CFLAGS+ are used.
> 
> I find the wording "By default, empty, so that the global
> +TARGET_CFLAGS+ are used" very confusing. Indeed, by default, those
> variables are not empty, they are precisely defined to TARGET_CFLAGS.
> 
> For example, in the autotools infra documentation, we say:
> 
> * +LIBFOO_AUTORECONF+, tells whether the package should
>   be autoreconfigured or not (i.e. if the configure script and
>   Makefile.in files should be re-generated by re-running autoconf,
>   automake, libtool, etc.). Valid values are +YES+ and
>   +NO+. By default, the value is +NO+
> 
> So we just say that the default value is NO, not that it is empty and
> that NO is used :)
> 
> For extra clarity, it could be rephrased like this:
> 
> 	When no value is specified by the package for this variable,
> 	the value of +TARGET_CFLAGS+ will be used by the
> 	+meson-package+ infrastructure.

Yes, that makes sense.

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCHv2] meson: add per package optional compiler/linker flags

[Yann E. MORIN]

All,

On 2019-06-22 22:20 +0200, Yann E. MORIN spake thusly:
> From: Peter Seiderer <ps.report@gmx.net>
> Add LIBFOO_CFLAGS, LIBFOO_LDFLAGS and LIBFOO_CXXFLAGS variables to allow
> packages to provide their own flags, possibly overriding the generic
> ones entirely, like we allow for other infras.
[--SNIP--]
> diff --git a/package/pkg-meson.mk b/package/pkg-meson.mk
> index 886fcf7205..807b578219 100644
> --- a/package/pkg-meson.mk
> +++ b/package/pkg-meson.mk
> @@ -57,6 +57,14 @@ $(2)_NINJA_ENV		?=
>  ifndef $(2)_CONFIGURE_CMDS
>  ifeq ($(4),target)
>  
> +$(2)_CFLAGS ?= $$(TARGET_CFLAGS)
> +$(2)_LDFLAGS ?= $$(TARGET_LDFLAGS)
> +$(2)_CXXFLAGS ?= $$(TARGET_CXXFLAGS)
> +
> +$(2)_MESON_SED_CFLAGS = $(if $($(2)_CFLAGS),`printf '"%s"$$(comma) ' $($(2)_CFLAGS)`)
> +$(2)_MESON_SED_LDFLAGS = $(if $($(2)_LDFLAGS),`printf '"%s"$$(comma) ' $($(2)_LDFLAGS)`)
> +$(2)_MESON_SED_CXXFLAGS = $(if $($(2)_CXXFLAGS),`printf '"%s"$$(comma) ' $$($$(2)_CXXFLAGS)`)

Gah... During my experimenting, I dropped the double-dollar in some
places, above. Damn...

I'll son respin, taking Thomas' comments into account.

Sorry for the noise...


Regards,
Yann E. MORIN.

> +
>  # Configure package for target
>  #
>  #
> @@ -67,9 +75,9 @@ define $(2)_CONFIGURE_CMDS
>  	    -e "s%@TARGET_ARCH@%$$(HOST_MESON_TARGET_CPU_FAMILY)%g" \
>  	    -e "s%@TARGET_CPU@%$$(GCC_TARGET_CPU)%g" \
>  	    -e "s%@TARGET_ENDIAN@%$$(call LOWERCASE,$$(BR2_ENDIAN))%g" \
> -	    -e "s%@TARGET_CFLAGS@%$$(HOST_MESON_SED_CFLAGS)%g" \
> -	    -e "s%@TARGET_LDFLAGS@%$$(HOST_MESON_SED_LDFLAGS)%g" \
> -	    -e "s%@TARGET_CXXFLAGS@%$$(HOST_MESON_SED_CXXFLAGS)%g" \
> +	    -e "s%@TARGET_CFLAGS@%$$($(2)_MESON_SED_CFLAGS)%g" \
> +	    -e "s%@TARGET_LDFLAGS@%$$($(2)_MESON_SED_LDFLAGS)%g" \
> +	    -e "s%@TARGET_CXXFLAGS@%$$($(2)_MESON_SED_CXXFLAGS)%g" \
>  	    -e "s%@HOST_DIR@%$$(HOST_DIR)%g" \
>  	    package/meson/cross-compilation.conf.in \
>  	    > $$($$(PKG)_SRCDIR)/build/cross-compilation.conf
> -- 
> 2.20.1
> 

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'