Re: [PATCH] trace-cmd: Allow building with GNU Make 4.4

[Daniel Wagner <dwagner@suse.de>]

Hi Michal,

On Mon, Dec 26, 2022 at 05:49:51PM +0100, Michal Sojka wrote:
> Make 4.4 introduces several backward incompatibilities and the result
> is that building trace-cmd with it never finishes. It seems that make
> ends up in some kind of infinite recursion. The symptoms are:
> 
>     $ make -d
>     GNU Make 4.4
>     Built for x86_64-pc-linux-gnu
>     Copyright (C) 1988-2022 Free Software Foundation, Inc.
>     License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>
>     This is free software: you are free to change and redistribute it.
>     There is NO WARRANTY, to the extent permitted by law.
>     Reading makefiles...
>     Reading makefile 'Makefile'...
>     Makefile:79: not recursively expanding pkgconfig_dir to export to shell function
>     Makefile:79: not recursively expanding pkgconfig_dir to export to shell function
>     Makefile:224: not recursively expanding LIBTRACECMD_SHARED_VERSION to export to shell function
>     Makefile:79: not recursively expanding pkgconfig_dir to export to shell function
>     Makefile:224: not recursively expanding LIBTRACECMD_SHARED_VERSION to export to shell function
>     Makefile:225: not recursively expanding LIBTRACECMD_SHARED_SO to export to shell function
>     Makefile:79: not recursively expanding pkgconfig_dir to export to shell function
>     Makefile:79: not recursively expanding pkgconfig_dir to export to shell function
> 
> Build succeeds if recursively expanded variables (defined with '='),
> which use $(shell ...) as its value, are replaced with simply expanded
> variables (defined with ':=').
> 
> Signed-off-by: Michal Sojka <michal.sojka@cvut.cz>

This seems to address my make troubles. I am again able to build trace-cmd with make v4.4. Thanks!

Tested-by: Daniel Wagner <dwagner@suse.de>

> ---
>  Makefile | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index bda49dd..d50e625 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -221,8 +221,8 @@ LIBS ?= -ldl
>  LIBTRACECMD_DIR = $(obj)/lib/trace-cmd
>  LIBTRACECMD_STATIC = $(LIBTRACECMD_DIR)/libtracecmd.a
>  LIBTRACECMD_SHARED = $(LIBTRACECMD_DIR)/libtracecmd.so.$(LIBTRACECMD_VERSION)
> -LIBTRACECMD_SHARED_VERSION = $(shell echo $(LIBTRACECMD_SHARED) | sed -e 's/\(\.so\.[0-9]*\).*/\1/')
> -LIBTRACECMD_SHARED_SO = $(shell echo $(LIBTRACECMD_SHARED) | sed -e 's/\(\.so\).*/\1/')
> +LIBTRACECMD_SHARED_VERSION := $(shell echo $(LIBTRACECMD_SHARED) | sed -e 's/\(\.so\.[0-9]*\).*/\1/')
> +LIBTRACECMD_SHARED_SO := $(shell echo $(LIBTRACECMD_SHARED) | sed -e 's/\(\.so\).*/\1/')
>  
>  export LIBTRACECMD_STATIC LIBTRACECMD_SHARED
>  export LIBTRACECMD_SHARED_VERSION LIBTRACECMD_SHARED_SO
> @@ -230,12 +230,12 @@ export LIBTRACECMD_SHARED_VERSION LIBTRACECMD_SHARED_SO
>  LIBTRACEEVENT=libtraceevent
>  LIBTRACEFS=libtracefs
>  
> -TEST_LIBTRACEEVENT = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEEVENT_MIN_VERSION) $(LIBTRACEEVENT) > /dev/null 2>&1 && echo y")
> -TEST_LIBTRACEFS = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEFS_MIN_VERSION) $(LIBTRACEFS) > /dev/null 2>&1 && echo y")
> +TEST_LIBTRACEEVENT := $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEEVENT_MIN_VERSION) $(LIBTRACEEVENT) > /dev/null 2>&1 && echo y")
> +TEST_LIBTRACEFS := $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEFS_MIN_VERSION) $(LIBTRACEFS) > /dev/null 2>&1 && echo y")
>  
>  ifeq ("$(TEST_LIBTRACEEVENT)", "y")
> -LIBTRACEEVENT_CFLAGS = $(shell sh -c "$(PKG_CONFIG) --cflags $(LIBTRACEEVENT)")
> -LIBTRACEEVENT_LDLAGS = $(shell sh -c "$(PKG_CONFIG) --libs $(LIBTRACEEVENT)")
> +LIBTRACEEVENT_CFLAGS := $(shell sh -c "$(PKG_CONFIG) --cflags $(LIBTRACEEVENT)")
> +LIBTRACEEVENT_LDLAGS := $(shell sh -c "$(PKG_CONFIG) --libs $(LIBTRACEEVENT)")
>  else
>  .PHONY: warning
>  warning:
> @@ -253,8 +253,8 @@ endif
>  export LIBTRACEEVENT_CFLAGS LIBTRACEEVENT_LDLAGS
>  
>  ifeq ("$(TEST_LIBTRACEFS)", "y")
> -LIBTRACEFS_CFLAGS = $(shell sh -c "$(PKG_CONFIG) --cflags $(LIBTRACEFS)")
> -LIBTRACEFS_LDLAGS = $(shell sh -c "$(PKG_CONFIG) --libs $(LIBTRACEFS)")
> +LIBTRACEFS_CFLAGS := $(shell sh -c "$(PKG_CONFIG) --cflags $(LIBTRACEFS)")
> +LIBTRACEFS_LDLAGS := $(shell sh -c "$(PKG_CONFIG) --libs $(LIBTRACEFS)")
>  else
>  .PHONY: warning
>  warning:
> @@ -324,11 +324,11 @@ endif
>  export ZLIB_LDLAGS
>  
>  ifndef NO_LIBZSTD
> -TEST_LIBZSTD = $(shell sh -c "$(PKG_CONFIG) --atleast-version 1.4.0 libzstd > /dev/null 2>&1 && echo y")
> +TEST_LIBZSTD := $(shell sh -c "$(PKG_CONFIG) --atleast-version 1.4.0 libzstd > /dev/null 2>&1 && echo y")
>  
>  ifeq ("$(TEST_LIBZSTD)", "y")
> -LIBZSTD_CFLAGS = $(shell sh -c "$(PKG_CONFIG) --cflags libzstd")
> -LIBZSTD_LDLAGS = $(shell sh -c "$(PKG_CONFIG) --libs libzstd")
> +LIBZSTD_CFLAGS := $(shell sh -c "$(PKG_CONFIG) --cflags libzstd")
> +LIBZSTD_LDLAGS := $(shell sh -c "$(PKG_CONFIG) --libs libzstd")
>  CFLAGS += -DHAVE_ZSTD
>  ZSTD_INSTALLED=1
>  $(info    Have ZSTD compression support)
> -- 
> 2.38.1
>