GNUmakefile: mv Makefile GNUmakefile

We require GNU Make.  Let's make it explicit by using the appropriate
GNU Make makefile name.  This will avoid users innocently running other
make(1) implementations and be confused by errors, as happened with Ingo
Schwarze long ago.

Cc: Ingo Schwarze <schwarze@openbsd.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

1 files changed, 235 insertions, 0 deletions

diff --git a/GNUmakefile b/GNUmakefile
new file mode 100644
index 000000000..64a29b2fd
--- /dev/null
+++ b/GNUmakefile
@@ -0,0 +1,235 @@
+########################################################################
+# Copyright 2021-2023, Alejandro Colomar <alx@kernel.org>
+# SPDX-License-Identifier: GPL-3.0-or-later
+########################################################################
+# Conventions:
+#
+# - Follow "Makefile Conventions" from the "GNU Coding Standards" closely.
+#   However, when something could be improved, don't follow those.
+# - Uppercase variables, when referring files, refer to files in this repo.
+# - Lowercase variables, when referring files, refer to system files.
+# - Lowercase variables starting with '_' refer to absolute paths,
+#   including $(DESTDIR).
+# - Uppercase variables starting with '_' refer to temporary files produced
+#   in $builddir.
+# - Variables ending with '_' refer to a subdir of their parent dir, which
+#   is in a variable of the same name but without the '_'.  The subdir is
+#   named after this project: <*/man>.
+# - Variables ending in '_rm' refer to files that can be removed (exist).
+# - Targets of the form '%-rm' remove their corresponding file '%'.
+#
+########################################################################
+
+
+ifndef MAKEFILE_INCLUDED
+MAKEFILE_INCLUDED := 1
+
+
+SHELL := /usr/bin/env bash -Eeuo pipefail
+
+
+MAKEFLAGS += --no-builtin-rules
+MAKEFLAGS += --no-builtin-variables
+MAKEFLAGS += --warn-undefined-variables
+
+
+srcdir      := .
+DATAROOTDIR := $(srcdir)/share
+MAKEFILEDIR := $(DATAROOTDIR)/mk
+
+
+.PHONY: all
+all: build;
+
+.PHONY: help
+help:
+	$(info	all			Alias for "build")
+	$(info	)
+	$(info	clean			Remove $$(builddir))
+	$(info	)
+	$(info	build			Wrapper for build-* targets)
+	$(info	)
+	$(info	build-pre		Preprocess man pages; alias for "build-pre-tbl")
+	$(info	build-pre-preconv	Preprocess man pages with preconv(1))
+	$(info	build-pre-tbl		Preprocess man pages with tbl(1))
+	$(info	)
+	$(info	build-catman		Build cat pages; alias for "build-catman-grotty")
+	$(info	build-catman-eqn	eqn(1) step of "build-catman")
+	$(info	build-catman-troff	Wrapper for build-catman-troff-* targets)
+	$(info	build-catman-troff-man	troff(1) step of "build-catman" for man(7) pages)
+	$(info	build-catman-troff-mdoc	troff(1) step of "build-catman" for mdoc(7) pages)
+	$(info	build-catman-grotty	grotty(1) step of "build-catman")
+	$(info	)
+	$(info	build-html		Build HTML manual pages)
+	$(info	html			Alias for "build-html")
+	$(info	)
+	$(info	build-pdf		Build PDF manual pages; alias for "build-pdf-grops")
+	$(info	build-pdf-eqn		eqn(1) step of "build-pdf")
+	$(info	build-pdf-troff		Wrapper for build-pdf-troff-* targets)
+	$(info	build-pdf-troff-man	troff(1) step of "build-pdf" for man(7) pages)
+	$(info	build-pdf-troff-mdoc	troff(1) step of "build-pdf" for mdoc(7) pages)
+	$(info	build-pdf-gropdf	gropdf(1) step of "build-pdf")
+	$(info	)
+	$(info	build-ps		Build PostScript manual pages; alias for "build-ps-grops")
+	$(info	build-ps-eqn		eqn(1) step of "build-ps")
+	$(info	build-ps-troff		Wrapper for build-ps-troff-* targets)
+	$(info	build-ps-troff-man	troff(1) step of "build-ps" for man(7) pages)
+	$(info	build-ps-troff-mdoc	troff(1) step of "build-ps" for mdoc(7) pages)
+	$(info	build-ps-grops		grops(1) step of "build-ps")
+	$(info	)
+	$(info	build-src		Alias for "build-src-ld")
+	$(info	build-src-c		Extract C programs from EXAMPLES)
+	$(info	build-src-cc		Compile C programs from EXAMPLES)
+	$(info	build-src-ld		Link C programs from EXAMPLES)
+	$(info	)
+	$(info	lint			Wrapper for "lint-c lint-man lint-mdoc")
+	$(info	lint-c			Wrapper for lint-c-* targets)
+	$(info	lint-c-checkpatch	Lint C programs from EXAMPLES with checkpatch(1))
+	$(info	lint-c-clang-tidy	Lint C programs from EXAMPLES with clang-tidy(1))
+	$(info	lint-c-cppcheck		Lint C programs from EXAMPLES with cppcheck(1))
+	$(info	lint-c-cpplint		Lint C programs from EXAMPLES with cpplint(1))
+	$(info	lint-c-iwyu		Lint C programs from EXAMPLES with iwyu(1))
+	$(info	lint-man		Wrapper for lint-man-* targets)
+	$(info	lint-man-mandoc		Lint man(7) pages with mandoc(1))
+	$(info	lint-man-tbl		Lint man(7) pages about '\" t' comment for tbl(1))
+	$(info	lint-mdoc		Wrapper for lint-mdoc-* targets)
+	$(info	lint-mdoc-mandoc	Lint mdoc(7) pages with mandoc(1))
+	$(info	)
+	$(info	check			Alias for "check-catman")
+	$(info	check-catman		Check cat pages; alias for "check-catman-grep")
+	$(info	check-catman-col	Filter cat pages with col(1))
+	$(info	check-catman-grep	Check cat pages with grep(1))
+	$(info	)
+	$(info	[un]install		Alias for "[un]install-man")
+	$(info	[un]install-man		Wrapper for [un]install-man* targets)
+	$(info	[un]install-manintro	[Un]install intro(*) man pages)
+	$(info	[un]install-man1	[Un]install man pages in section 1)
+	$(info	[un]install-man2	[Un]install man pages in section 2)
+	$(info	[un]install-man2type	[Un]install man pages in section 2type)
+	$(info	[un]install-man3	[Un]install man pages in section 3)
+	$(info	[un]install-man3const	[Un]install man pages in section 3const)
+	$(info	[un]install-man3head	[Un]install man pages in section 3head)
+	$(info	[un]install-man3type	[Un]install man pages in section 3type)
+	$(info	[un]install-man4	[Un]install man pages in section 4)
+	$(info	[un]install-man5	[Un]install man pages in section 5)
+	$(info	[un]install-man6	[Un]install man pages in section 6)
+	$(info	[un]install-man7	[Un]install man pages in section 7)
+	$(info	[un]install-man8	[Un]install man pages in section 8)
+	$(info	)
+	$(info	[un]install-html	[Un]install HTML manual pages)
+	$(info	)
+	$(info	dist			Wrapper for dist-* targets)
+	$(info	dist-tar		Create a tarball of the repository)
+	$(info	dist-bz2		Create a compressed tarball (.tar.bz2))
+	$(info	dist-gz			Create a compressed tarball (.tar.gz))
+	$(info	dist-lz			Create a compressed tarball (.tar.lz))
+	$(info	dist-xz			Create a compressed tarball (.tar.xz))
+	$(info	)
+	$(info	help			Print this help)
+	$(info	help-variables		Print all variables available, and their default values)
+	$(info	)
+
+
+.SECONDEXPANSION:
+
+
+MK := \
+	$(srcdir)/Makefile \
+	$(wildcard $(addprefix $(MAKEFILEDIR)/, *.mk */*.mk */*/*.mk))
+include $(MK)
+$(MK):: ;
+
+
+.PHONY: help-variables
+help-variables:
+	$(info	V		Define to non-empty string for verbose output)
+	$(info	)
+	$(info	LINK_PAGES	How to install link pages.  [".so", "symlink"])
+	$(info	Z		Install pages compressed.  ["", ".bz2", ".gz", ".lz", ".xz"])
+	$(info	)
+	$(info	DISTNAME	$$(git describe))
+	$(info	DISTVERSION	/$$DISTNAME/s/man-pages-//)
+	$(info	)
+	$(info	# Directory variables:)
+	$(info	)
+	$(info	builddir	.tmp)
+	$(info	DESTDIR		)
+	$(info	prefix		/usr/local)
+	$(info	mandir		$$(datarootdir)/man)
+	$(info	docdir		$$(datarootdir)/doc)
+	$(info	)
+	$(info	man1dir		$$(mandir)/man1)
+	$(info	man2dir		$$(mandir)/man2)
+	$(info	man2typedir	$$(mandir)/man2type)
+	$(info	man3dir		$$(mandir)/man3)
+	$(info	man3constdir	$$(mandir)/man3const)
+	$(info	man3headdir	$$(mandir)/man3head)
+	$(info	man3typedir	$$(mandir)/man3type)
+	$(info	man4dir		$$(mandir)/man4)
+	$(info	man5dir		$$(mandir)/man5)
+	$(info	man6dir		$$(mandir)/man6)
+	$(info	man7dir		$$(mandir)/man7)
+	$(info	man8dir		$$(mandir)/man8)
+	$(info	)
+	$(info	htmldir		$$(docdir))
+	$(info	htmlext		.html)
+	$(info	)
+	$(info	# Command variables (and flags):)
+	$(info	)
+	$(info	-		MANWIDTH)
+	$(info	-		NROFF_OUT_DEVICE)
+	$(info	PRECONV		{EXTRA_,}PRECONVFLAGS)
+	$(info	TBL)
+	$(info	EQN		{EXTRA_,}EQNFLAGS)
+	$(info	TROFF		{EXTRA_,}TROFFFLAGS{,_MAN,_MDOC}	{EXTRA_,}NROFFFLAGS)
+	$(info	GROPDF		{EXTRA_,}GROPDFFLAGS)
+	$(info	GROPS		{EXTRA_,}GROPSFLAGS)
+	$(info	GROTTY		{EXTRA_,}GROTTYFLAGS)
+	$(info	COL		{EXTRA_,}COLFLAGS)
+	$(info	)
+	$(info	MANDOC		{EXTRA_,}MANDOCFLAGS)
+	$(info	MAN2HTML	{EXTRA_,}MAN2HTMLFLAGS)
+	$(info	)
+	$(info	BZIP2		{EXTRA_,}BZIP2FLAGS)
+	$(info	CP)
+	$(info	ECHO)
+	$(info	EXPR)
+	$(info	FIND)
+	$(info	GIT)
+	$(info	GZIP		{EXTRA_,}GZIPFLAGS)
+	$(info	HEAD)
+	$(info	LN)
+	$(info	LOCALE)
+	$(info	LZIP		{EXTRA_,}LZIPFLAGS)
+	$(info	PKGCONF)
+	$(info	SED)
+	$(info	SORTMAN)
+	$(info	SPONGE)
+	$(info	TAC)
+	$(info	TAIL)
+	$(info	TAR)
+	$(info	TEST)
+	$(info	XARGS)
+	$(info	XZ		{EXTRA_,}XZFLAGS)
+	$(info	)
+	$(info	INSTALL)
+	$(info	INSTALL_DATA)
+	$(info	MKDIR)
+	$(info	RM)
+	$(info	)
+	$(info	-		{EXTRA_,}CPPFLAGS)
+	$(info	CC		{EXTRA_,}CFLAGS)
+	$(info	LD		{EXTRA_,}LDFLAGS	{EXTRA_,}LDLIBS)
+	$(info	)
+	$(info	CHECKPATCH	{EXTRA_,}CHECKPATCHFLAGS)
+	$(info	CLANG-TIDY	{EXTRA_,}CLANG-TIDYFLAGS)
+	$(info	CPPCHECK	{EXTRA_,}CPPCHECKFLAGS)
+	$(info	CPPLINT		{EXTRA_,}CPPLINTFLAGS)
+	$(info	IWYU		{EXTRA_,}IWYUFLAGS)
+	$(info	)
+
+
+.DELETE_ON_ERROR:
+
+
+endif  #include guard