refactor(build): Adapt custom macro for upstreaming to autoconf-archive

Since I seem to use this on every project I touch now, I went ahead and
spruced it up in a way that should make it acceptable as a contribution
to autoconf-archive. As of tihs writing it has been PR'ed but not
morged, so consider the exact script with this serial still fungable.

autoconf-archive/autoconf-archive#324

build-aux/ax_require_prog.m4

@@ -0,0 +1,49 @@
+# ===========================================================================
+#     https://www.gnu.org/software/autoconf-archive/ax_require_prog.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_REQUIRE_PROG([EXECUTABLE], [VARIABLE])
+#
+# DESCRIPTION
+#
+#   Locates an installed binary program that is a prerequisite to continue.
+#   Uses AX_WITH_PROG under the hood, but follows up the check with an error
+#   if no executable could be located.
+#
+#   Example usage:
+#
+#     AX_REQUIRE_PROG(git-warp-time)
+#
+#   Note: If the second argument is not provided, a default value of
+#   VARIABLE is automatically derived from the executable name by upper
+#   casing it and substituting any dashes or periods with underscores. In
+#   the example above the resulting precious variable would be
+#   GIT_WARP_TIME.
+#
+# LICENSE
+#
+#   Copyright (c) 2021 Caleb Maclennan <[email protected]>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 1
+
+AC_DEFUN([AX_REQUIRE_PROG], [
+    AC_PREREQ([2.61])
+
+    pushdef([EXECUTABLE],$1)
+    pushdef([VARIABLE],m4_default($2,m4_toupper(m4_translit($1,-.,__))))
+
+    AX_WITH_PROG(VARIABLE,EXECUTABLE)
+    AS_IF([test "x$with_$1" != xno && test -z "$VARIABLE"], [
+        AC_MSG_ERROR([EXECUTABLE is required])
+    ])
+
+    popdef([VARIABLE])
+    popdef([EXECUTABLE])
+])

build-aux/que_dist_checksums.m4

@@ -9,8 +9,8 @@ EXTRA_DIST += build-aux/que_dist_checksums.am
 
         AM_COND_IF([DEVELOPER_MODE], [
 
-                QUE_PROGVAR([sha256sum])
-                QUE_PROGVAR([tee])
+                AX_REQUIRE_PROG([sha256sum])
+                AX_REQUIRE_PROG([tee])
 
                 AX_ADD_AM_MACRO([dnl
 $(cat build-aux/que_dist_checksums.am)

build-aux/que_docker_boilerplate.m4

@@ -5,7 +5,7 @@ AC_DEFUN_ONCE([QUE_DOCKER_BOILERPLATE], [
         AC_MSG_NOTICE([checking for tools used by automake to build Docker projects])
         AC_REQUIRE([AC_PROG_INSTALL])
         AM_COND_IF([DEVELOPER_MODE], [
-                QUE_PROGVAR([docker])
+                AX_REQUIRE_PROG([docker])
         ])
 
         AC_REQUIRE([AX_AM_MACROS])

build-aux/que_git_version.m4

@@ -14,7 +14,7 @@ AC_DEFUN_ONCE([QUE_GIT_VERSION], [
 
         QUE_TRANSFORM_PACKAGE_NAME
 
-        AM_COND_IF([SOURCE_IS_DIST], [], [QUE_PROGVAR([cmp])])
+        AM_COND_IF([SOURCE_IS_DIST], [], [AX_REQUIRE_PROG([cmp])])
 
         AC_REQUIRE([AX_AM_MACROS])
         AX_ADD_AM_MACRO([dnl

build-aux/que_rust_boilerplate.m4

@@ -12,14 +12,14 @@ AC_DEFUN_ONCE([QUE_RUST_BOILERPLATE], [
         AC_MSG_NOTICE([checking for tools used by automake to build Rust projects])
         AC_REQUIRE([AC_PROG_INSTALL])
         AC_REQUIRE([AC_PROG_SED])
-        QUE_PROGVAR([cargo])
-        QUE_PROGVAR([jq])
-        QUE_PROGVAR([rustc])
-        QUE_PROGVAR([cmp])
-        QUE_PROGVAR([xargs])
+        AX_REQUIRE_PROG([cargo])
+        AX_REQUIRE_PROG([jq])
+        AX_REQUIRE_PROG([rustc])
+        AX_REQUIRE_PROG([cmp])
+        AX_REQUIRE_PROG([xargs])
         AM_COND_IF([DEVELOPER_MODE], [
-                QUE_PROGVAR([git])
-                QUE_PROGVAR([rustfmt])
+                AX_REQUIRE_PROG([git])
+                AX_REQUIRE_PROG([rustfmt])
         ])
 
         AC_ARG_VAR(CARGO_TARGET_TRIPLE, "Target triple for Rust compilations")

build-aux/que_subst_man_date.m4

@@ -3,10 +3,10 @@ AC_DEFUN([QUE_SUBST_MAN_DATE], [
         ax_src_file="m4_default($2,*.1.in)"
         AS_IF([test ! -e .gitignore],
                 [
-                        QUE_PROGVAR([date])
+                        AX_REQUIRE_PROG([date])
                         AX_BUILD_DATE_EPOCH(MAN_DATE, "$ax_date_fmt")
                 ], [
-                        QUE_PROGVAR([git])
+                        AX_REQUIRE_PROG([git])
                         MAN_DATE=$($GIT log -1 --format="%cd" --date=format:"$ax_date_fmt" -- $ax_src_file)
                 ])
         AC_SUBST([MAN_DATE])

configure.ac

@@ -21,15 +21,15 @@ AC_PROG_CC
 AC_PROG_GREP
 AC_PROG_OBJC
 AC_PROG_SED
-QUE_PROGVAR([cmp])
-QUE_PROGVAR([diff])
-QUE_PROGVAR([find])
-QUE_PROGVAR([head])
-QUE_PROGVAR([jq])
-QUE_PROGVAR([luarocks])
-QUE_PROGVAR([pdfinfo])
-QUE_PROGVAR([sort])
-QUE_PROGVAR([xargs])
+AX_REQUIRE_PROG([cmp])
+AX_REQUIRE_PROG([diff])
+AX_REQUIRE_PROG([find])
+AX_REQUIRE_PROG([head])
+AX_REQUIRE_PROG([jq])
+AX_REQUIRE_PROG([luarocks])
+AX_REQUIRE_PROG([pdfinfo])
+AX_REQUIRE_PROG([sort])
+AX_REQUIRE_PROG([xargs])
 
 # Disable ranlib to avoid it being run on our rusile.so module, already LTO
 # optimized but libtool wants to relink it...
@@ -119,8 +119,8 @@ AM_CONDITIONAL([FONT_DOWNLOAD_TOOLS], [test -z ${DEVELOPER_MODE_TRUE} || (test -
 AC_SUBST([FONT_DOWNLOAD_TOOLS])
 
 AM_COND_IF([MANUAL], [
-            QUE_PROGVAR([dot])
-            QUE_PROGVAR([gs])
+            AX_REQUIRE_PROG([dot])
+            AX_REQUIRE_PROG([gs])
             ])
 
 AC_MSG_CHECKING([for OS X])
@@ -189,8 +189,8 @@ AM_CONDITIONAL([ICU], [test "x$with_icu" = "xyes"])
 # Required for downloading fonts for the manual and for tests
 # Since the source tarball includes a prebuilt manual we only need this for Git source builds
 AM_COND_IF([FONT_DOWNLOAD_TOOLS], [
-    QUE_PROGVAR([bsdtar])
-    QUE_PROGVAR([curl])
+    AX_REQUIRE_PROG([bsdtar])
+    AX_REQUIRE_PROG([curl])
 ])
 
 AM_COND_IF([DEVELOPER_MODE], [
@@ -199,19 +199,19 @@ AM_COND_IF([DEVELOPER_MODE], [
 ])
 
 AM_COND_IF([DEVELOPER_TOOLS], [
-    QUE_PROGVAR([busted])
-    QUE_PROGVAR([cargosetversion], [cargo-set-version])
-    QUE_PROGVAR([curl])
-    QUE_PROGVAR([ldoc])
-    QUE_PROGVAR([luacheck])
-    QUE_PROGVAR([nix])
-    QUE_PROGVAR([npm])
-    QUE_PROGVAR([perl])
-    QUE_PROGVAR([stylua])
-    QUE_PROGVAR([taplo])
-    QUE_PROGVAR([tr])
-    QUE_PROGVAR([typos])
-    QUE_PROGVAR([xsltproc])
+    AX_REQUIRE_PROG([busted])
+    AX_REQUIRE_PROG([cargo-set-version])
+    AX_REQUIRE_PROG([curl])
+    AX_REQUIRE_PROG([ldoc])
+    AX_REQUIRE_PROG([luacheck])
+    AX_REQUIRE_PROG([nix])
+    AX_REQUIRE_PROG([npm])
+    AX_REQUIRE_PROG([perl])
+    AX_REQUIRE_PROG([stylua])
+    AX_REQUIRE_PROG([taplo])
+    AX_REQUIRE_PROG([tr])
+    AX_REQUIRE_PROG([typos])
+    AX_REQUIRE_PROG([xsltproc])
 ])
 
 AX_PROG_LUA([5.1], [], [], [], [prefer])
@@ -242,7 +242,7 @@ AM_COND_IF([SYSTEM_LUAROCKS], [
     AX_LUA_MODULE(penlight, pl)
     AX_LUA_MODULE(vstruct)
 ], [
-    QUE_PROGVAR([git]) # required for luarocks to install zlib rock
+    AX_REQUIRE_PROG([git]) # required for luarocks to install zlib rock
 ])
 
 QUE_FONT(Gentium Plus)