Merge branch 'develop' of git://github.com/sagemath/sage into public/…

…build/inplace_ext

.github/workflows/ci-cygwin-minimal.yml

@@ -84,7 +84,7 @@ jobs:
   cygwin-stage-i-b:
     env:
       STAGE: i-b
-      TARGETS: cython setuptools_scm kiwisolver dateutil cycler pyparsing nose certifi pkgconfig pplpy
+      TARGETS: cython setuptools_scm kiwisolver dateutil cycler pyparsing certifi pkgconfig pplpy
       LOCAL_ARTIFACT_NAME: sage-local-commit-${{ github.sha }}-cygwin-${{ matrix.pkgs }}
       LOGS_ARTIFACT_NAME: logs-commit-${{ github.sha }}-cygwin-${{ matrix.pkgs }}
 

.github/workflows/ci-cygwin-standard.yml

@@ -84,7 +84,7 @@ jobs:
   cygwin-stage-i-b:
     env:
       STAGE: i-b
-      TARGETS: cython setuptools_scm kiwisolver dateutil cycler pyparsing nose certifi pkgconfig pplpy
+      TARGETS: cython setuptools_scm kiwisolver dateutil cycler pyparsing certifi pkgconfig pplpy
       LOCAL_ARTIFACT_NAME: sage-local-commit-${{ github.sha }}-cygwin-${{ matrix.pkgs }}
       LOGS_ARTIFACT_NAME: logs-commit-${{ github.sha }}-cygwin-${{ matrix.pkgs }}
 

.github/workflows/tox-experimental.yml

@@ -48,7 +48,9 @@ jobs:
       TOX_ENV: docker-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
       LOGS_ARTIFACT_NAME: logs-commit-${{ github.sha }}-tox-docker-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
       DOCKER_TARGETS: configured with-targets with-targets-optional
-      TARGETS_OPTIONAL: "$( echo $(PATH=build/bin:$PATH build/bin/sage-package list :experimental: | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep '^[${{ matrix.targets_pattern }}]' ) )"
+      # Test all non-dummy experimental packages, but do not test huge packages
+      # and do not test packages that require external software
+      TARGETS_OPTIONAL: "$( echo $(export PATH=build/bin:$PATH && sage-package list :experimental: --has-file spkg-install.in && sage-package list :experimental: --has-file spkg-install && sage-package list :experimental: --has-file requirements.txt | grep -v ^_ | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep -v cplex | grep -v gurobi | grep '^[${{ matrix.targets_pattern }}]' ) )"
     steps:
       - uses: actions/checkout@v2
         with:
@@ -147,7 +149,9 @@ jobs:
     env:
       TOX_ENV: local-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
       LOGS_ARTIFACT_NAME: logs-commit-${{ github.sha }}-tox-local-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}-${{ matrix.os }}-xcode_${{ matrix.xcode_version_factor }}
-      TARGETS_OPTIONAL: "$( echo $(PATH=build/bin:$PATH build/bin/sage-package list :experimental: | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep '^[${{ matrix.targets_pattern }}]' ) )"
+      # Test all non-dummy experimental packages, but do not test huge packages
+      # and do not test packages that require external software
+      TARGETS_OPTIONAL: "$( echo $(export PATH=build/bin:$PATH && sage-package list :experimental: --has-file spkg-install.in && sage-package list :experimental: --has-file spkg-install && sage-package list :experimental: --has-file requirements.txt | grep -v ^_ | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep -v cplex | grep -v gurobi | grep '^[${{ matrix.targets_pattern }}]' ) )"
     steps:
       - uses: actions/checkout@v2
       - name: Select Xcode version

.github/workflows/tox-optional.yml

@@ -48,9 +48,9 @@ jobs:
       TOX_ENV: docker-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
       LOGS_ARTIFACT_NAME: logs-commit-${{ github.sha }}-tox-docker-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
       DOCKER_TARGETS: configured with-targets with-targets-optional
-      # Test all optional packages, but do not test huge packages,
+      # Test all non-dummy optional packages, but do not test huge packages
       # and do not test packages that require external software
-      TARGETS_OPTIONAL: "$( echo $(PATH=build/bin:$PATH build/bin/sage-package list :optional: | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep -v cplex | grep -v gurobi | grep '^[${{ matrix.targets_pattern }}]' ) )"
+      TARGETS_OPTIONAL: "$( echo $(export PATH=build/bin:$PATH && (sage-package list :optional: --has-file spkg-install.in && sage-package list :optional: --has-file spkg-install && sage-package list :optional: --has-file requirements.txt) | grep -v ^_ | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep -v cplex | grep -v gurobi | grep '^[${{ matrix.targets_pattern }}]' ) )"
     steps:
       - uses: actions/checkout@v2
         with:
@@ -149,9 +149,9 @@ jobs:
     env:
       TOX_ENV: local-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
       LOGS_ARTIFACT_NAME: logs-commit-${{ github.sha }}-tox-local-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}-${{ matrix.os }}-xcode_${{ matrix.xcode_version_factor }}
-      # Test all optional packages, but do not test huge packages
+      # Test all non-dummy optional packages, but do not test huge packages
       # and do not test packages that require external software
-      TARGETS_OPTIONAL: "$( echo $(PATH=build/bin:$PATH build/bin/sage-package list :optional: | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep -v cplex | grep -v gurobi | grep '^[${{ matrix.targets_pattern }}]' ) )"
+      TARGETS_OPTIONAL: "$( echo $(export PATH=build/bin:$PATH && (sage-package list :optional: --has-file spkg-install.in && sage-package list :optional: --has-file spkg-install && sage-package list :optional: --has-file requirements.txt) | grep -v ^_ | grep -v  database_stein_watkins\\$ | grep -v polytopes_db_4d | grep -v cplex | grep -v gurobi | grep '^[${{ matrix.targets_pattern }}]' ) )"
     steps:
       - uses: actions/checkout@v2
       - name: Select Xcode version

.gitignore

@@ -182,6 +182,7 @@ src/*.egg-info/
 /src/bin/sage-src-env-config
 
 # Virtual environments
+/venv
 src/.env
 src/.venv
 src/env/

.zenodo.json

@@ -1,10 +1,10 @@
 {
     "description": "Mirror of the Sage https://sagemath.org/ source tree", 
     "license": "other-open", 
-    "title": "sagemath/sage: 9.5.beta3", 
-    "version": "9.5.beta3", 
+    "title": "sagemath/sage: 9.5.beta4", 
+    "version": "9.5.beta4", 
     "upload_type": "software", 
-    "publication_date": "2021-10-11", 
+    "publication_date": "2021-10-19", 
     "creators": [
         {
             "affiliation": "SageMath.org", 
@@ -15,7 +15,7 @@
     "related_identifiers": [
         {
             "scheme": "url", 
-            "identifier": "https://github.com/sagemath/sage/tree/9.5.beta3", 
+            "identifier": "https://github.com/sagemath/sage/tree/9.5.beta4", 
             "relation": "isSupplementTo"
         }, 
         {

COPYING.txt

@@ -85,7 +85,6 @@ mistune                     Modified BSD
 mpc                         LGPLv3+
 mpfi                        COPYING is GPLv2, source files state LGPLv2.1+
 mpfr                        LGPLv3+
-mpir                        LGPLv3+
 mpmath                      Modified BSD
 networkx                    Modified BSD
 ntl                         GPLv2+

Makefile

@@ -109,6 +109,7 @@ distclean: build-clean
 	@echo "Deleting all remaining output from build system ..."
 	rm -rf local
 	rm -f src/bin/sage-env-config
+	rm -f prefix venv
 
 # Delete all auto-generated files which are distributed as part of the
 # source tarball

VERSION.txt

@@ -1 +1 @@
-SageMath version 9.5.beta3, Release Date: 2021-10-11
+SageMath version 9.5.beta4, Release Date: 2021-10-19

bootstrap

@@ -97,8 +97,13 @@ AS_VAR_SET_IF([SAGE_ENABLE_$pkgname], [], [AS_VAR_SET([SAGE_ENABLE_$pkgname], [y
                     case "$pkgname" in
                         _*) ;;
                         *)  spkg_configures="$spkg_configures
-AC_SUBST(SAGE_ENABLE_$pkgname, [if_installed])
-SAGE_SPKG_ENABLE([$pkgname], [$pkgtype], [$(head -n1 build/pkgs/$pkgname/SPKG.rst 2>/dev/null || echo $pkgname)])" ;;
+AC_SUBST(SAGE_ENABLE_$pkgname, [if_installed])"
+                            if [ -f build/pkgs/$pkgname/spkg-install -o -f build/pkgs/$pkgname/spkg-install.in ]; then
+                                # Trac #31163: Not just an optional dummy package
+                                spkg_configures="$spkg_configures
+SAGE_SPKG_ENABLE([$pkgname], [$pkgtype], [$(head -n1 build/pkgs/$pkgname/SPKG.rst 2>/dev/null || echo $pkgname)])"
+                            fi
+                            ;;
                     esac
                 fi
     done

build/bin/sage-print-system-package-command

@@ -149,6 +149,9 @@ case $system:$command in
     pip:install)
         [ -n "$system_packages" ] && print_shell_command "sage -pip install $system_packages"
         ;;
+    cpan:install)
+        [ -n "$system_packages" ] && print_shell_command "cpan -i $system_packages"
+        ;;
     repology:install)
         if [ -n "$system_packages" ]; then
             links=""

build/bin/sage-spkg-info

@@ -57,6 +57,7 @@ if [ $have_repology = yes ]; then
     systems="$systems repology"
 fi
 for system in $systems; do
+        system_package_file="$PKG_DISTROS"/$system.txt
         system_packages="$(echo $(sed 's/#.*//;' $system_package_file))"
         case $system in
             debian)

build/bin/write-dockerfile.sh

@@ -219,7 +219,7 @@ ARG NUMPROC=8
 ENV MAKE="make -j\${NUMPROC}"
 ARG USE_MAKEFLAGS="-k V=0"
 ENV SAGE_CHECK=warn
-ENV SAGE_CHECK_PACKAGES="!cython,!r,!python3,!python2,!nose,!pathpy,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!networkx,!rpy2,!symengine_py,!sage_sws2rst"
+ENV SAGE_CHECK_PACKAGES="!cython,!r,!python3,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!rpy2,!sage_sws2rst"
 #:toolchain:
 $RUN make \${USE_MAKEFLAGS} base-toolchain $ENDRUN
 
@@ -228,7 +228,7 @@ ARG NUMPROC=8
 ENV MAKE="make -j\${NUMPROC}"
 ARG USE_MAKEFLAGS="-k V=0"
 ENV SAGE_CHECK=warn
-ENV SAGE_CHECK_PACKAGES="!gfan,!cython,!r,!python3,!python2,!nose,!pathpy,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!networkx,!rpy2,!symengine_py,!sage_sws2rst"
+ENV SAGE_CHECK_PACKAGES="!gfan,!cython,!r,!python3,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!rpy2,!sage_sws2rst"
 #:make:
 ARG TARGETS_PRE="all-sage-local"
 $RUN make SAGE_SPKG="sage-spkg -y -o" \${USE_MAKEFLAGS} \${TARGETS_PRE} $ENDRUN
@@ -238,7 +238,7 @@ ARG NUMPROC=8
 ENV MAKE="make -j\${NUMPROC}"
 ARG USE_MAKEFLAGS="-k V=0"
 ENV SAGE_CHECK=warn
-ENV SAGE_CHECK_PACKAGES="!gfan,!cython,!r,!python3,!python2,!nose,!pathpy,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!networkx,!rpy2,!symengine_py,!sage_sws2rst"
+ENV SAGE_CHECK_PACKAGES="!gfan,!cython,!r,!python3,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!rpy2,!sage_sws2rst"
 ADD src src
 ARG TARGETS="build"
 $RUN make SAGE_SPKG="sage-spkg -y -o" \${USE_MAKEFLAGS} \${TARGETS} $ENDRUN
@@ -248,7 +248,7 @@ ARG NUMPROC=8
 ENV MAKE="make -j\${NUMPROC}"
 ARG USE_MAKEFLAGS="-k V=0"
 ENV SAGE_CHECK=warn
-ENV SAGE_CHECK_PACKAGES="!gfan,!cython,!r,!python3,!python2,!nose,!pathpy,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!networkx,!rpy2,!symengine_py,!sage_sws2rst"
+ENV SAGE_CHECK_PACKAGES="!gfan,!cython,!r,!python3,!gap,!cysignals,!linbox,!git,!ppl,!cmake,!rpy2,!sage_sws2rst"
 ARG TARGETS_OPTIONAL="ptest"
 $RUN make SAGE_SPKG="sage-spkg -y -o" \${USE_MAKEFLAGS} \${TARGETS_OPTIONAL} || echo "(error ignored)" $ENDRUN
 

build/make/Makefile.in

@@ -32,7 +32,7 @@ SPKG_INST_RELDIR = var/lib/sage/installed
 # Aliases for mutually exclusive standard packages selected at configure time
 TOOLCHAIN = @SAGE_TOOLCHAIN@
 PYTHON = python3
-MP_LIBRARY = @SAGE_MP_LIBRARY@
+MP_LIBRARY = gmp
 BLAS = openblas
 
 # pkgconfig files generated/installed at build time
@@ -535,8 +535,10 @@ $(1)-$(4)-no-deps:
 $(1)-no-deps: $(1)-$(4)-no-deps
 
 $(1)-$(4)-clean:
-	sage-spkg-uninstall $(if $(filter $(1),$(TOOLCHAIN_DEPS)),--keep-files) \
-		$(1) '$$($(4))'
+	if [ -d '$$($(4))' ]; then \
+	    sage-spkg-uninstall $(if $(filter $(1),$(TOOLCHAIN_DEPS)),--keep-files) \
+		$(1) '$$($(4))'; \
+	fi
 
 $(1)-clean: $(1)-$(4)-clean
 
@@ -630,16 +632,29 @@ $$($(4))/$(SPKG_INST_RELDIR)/$(1)-$(2): $(3)
 $(1): $$($(4))/$(SPKG_INST_RELDIR)/$(1)-$(2)
 
 $(1)-$(4)-no-deps:
-	$(AM_V_at)cd '$$(SAGE_ROOT)/build/pkgs/$(1)' && \
+	@if [ -x '$$(SAGE_ROOT)/build/pkgs/$(1)/spkg-install' ]; then \
+	    $(AM_V_at)cd '$$(SAGE_ROOT)/build/pkgs/$(1)' && \
 		. '$$(SAGE_ROOT)/src/bin/sage-src-env-config' && \
 		. '$$(SAGE_ROOT)/src/bin/sage-env-config' && \
 		. '$$(SAGE_ROOT)/src/bin/sage-env' && \
 		. '$$(SAGE_ROOT)/build/bin/sage-build-env-config' && \
 		. '$$(SAGE_ROOT)/build/bin/sage-build-env' && \
 		SAGE_SPKG_WHEELS=$$($(4))/var/lib/sage/wheels \
 		SAGE_INST_LOCAL=$$($(4)) \
-		sage-logger -p '$$(SAGE_ROOT)/build/pkgs/$(1)/spkg-install' '$$(SAGE_LOGS)/$(1)-$(2).log'
-	touch "$$($(4))/$(SPKG_INST_RELDIR)/$(1)-$(2)"
+		sage-logger -p '$$(SAGE_ROOT)/build/pkgs/$(1)/spkg-install' '$$(SAGE_LOGS)/$(1)-$(2).log' && \
+	    touch "$$($(4))/$(SPKG_INST_RELDIR)/$(1)-$(2)"; \
+	else \
+	    echo; \
+	    echo "Error: $(1) is a dummy script package that the Sage distribution uses"; \
+	    echo "to provide information about equivalent system packages."; \
+	    echo "It cannot be installed using the Sage distribution."; \
+	    echo "Please install it manually, for example using the system packages"; \
+	    echo "recommended at the end of a run of './configure'"; \
+	    echo "See below for package-specific information."; \
+	    echo; \
+	    $$(SAGE_ROOT)/build/bin/sage-spkg-info $(1); \
+	    exit 1; \
+	fi
 
 $(1)-no-deps: $(1)-$(4)-no-deps
 

build/pkgs/arb/SPKG.rst

@@ -25,14 +25,3 @@ Upstream Contact
  - https://arblib.org/
 
  - http://github.com/fredrik-johansson/arb/
-
-Dependencies
-------------
-
--  FLINT
--  MPIR or GMP
--  MPFR
-
-
-Special Update/Build Instructions
----------------------------------

build/pkgs/backcall/dependencies

@@ -1,4 +1,4 @@
-$(PYTHON) | $(PYTHON_TOOLCHAIN) flit_core toml
+$(PYTHON) | $(PYTHON_TOOLCHAIN) flit_core tomli
 
 ----------
 All lines of this file are ignored except the first.

build/pkgs/cddlib/SPKG.rst

@@ -31,8 +31,3 @@ Upstream Contact
 ----------------
 
 https://github.com/cddlib/cddlib
-
-Dependencies
-------------
-
--  gmp (or its fork mpir)

build/pkgs/cddlib/spkg-configure.m4

@@ -1,5 +1,5 @@
 SAGE_SPKG_CONFIGURE([cddlib], [
-  SAGE_SPKG_DEPCHECK([gmp mpir], [
+  SAGE_SPKG_DEPCHECK([gmp], [
     dnl The sage library uses BOTH cddexec and cddexec_gmp.
     dnl These two executables were introduced in cddlib-094j.
     AC_CHECK_PROGS([CDDEXEC], [cddexec])

build/pkgs/cocoalib/SPKG.rst

@@ -19,14 +19,3 @@ Upstream Contact
 -  Email: cocoa@dima.unige.it
 -  Website: http://cocoa.dima.unige.it/
 -  Releases: http://cocoa.dima.unige.it/cocoalib/
-
-Dependencies
-------------
-
--  GMP/MPIR
-
-
-Special Update/Build Instructions
----------------------------------
-
-None.

build/pkgs/configure/checksums.ini

@@ -1,4 +1,4 @@
 tarball=configure-VERSION.tar.gz
-sha1=9c45053634b6912dd4e4e68a483b5dbd483fc47d
-md5=11496f4636f7c19bb4cfbaf6e57af698
-cksum=2205302326
+sha1=1df4c487d374a7ea9eeda3a9234cc6eed81c1443
+md5=83d4327261e545f26d4ad318030823e8
+cksum=2968565921

build/pkgs/configure/package-version.txt

@@ -1 +1 @@
-32c0d4075fb515a073925ad1feefcc4fc349b47d
+e8ab458165ec5e5832adf702099f47f4cff94596

build/pkgs/cvxopt/dependencies

@@ -1,4 +1,4 @@
-$(PYTHON) numpy $(BLAS) gsl glpk suitesparse | $(PYTHON_TOOLCHAIN) pkgconfig nose matplotlib
+$(PYTHON) numpy $(BLAS) gsl glpk suitesparse | $(PYTHON_TOOLCHAIN) pkgconfig matplotlib $(and $(filter-out no,$(SAGE_CHECK_cvxopt)), pytest)
 
 matplotlib is needed to test cvxopt (i.e., if SAGE_CHECK=yes). See #12742.
 

build/pkgs/cvxopt/spkg-check.in

@@ -1,8 +1,3 @@
 cd src
 
-if ! command -v nosetests ; then 
-    echo >&2 'Testing cvxopt requires the package nose to be installed'
-    exit 1
-fi
-
-nosetests
+pytest

build/pkgs/e_antic/SPKG.rst

@@ -19,10 +19,3 @@ Upstream Contact
 ----------------
 
 -  https://github.com/videlec/e-antic
-
-Dependencies
-------------
-
--  GMP/MPIR
--  FLINT
--  ARB

build/pkgs/ecl/spkg-configure.m4

@@ -3,7 +3,7 @@ SAGE_SPKG_CONFIGURE([ecl], [
   # Default to installing the SPKG
   sage_spkg_install_ecl=yes
 
-  SAGE_SPKG_DEPCHECK([gcc gc gmp mpir], [
+  SAGE_SPKG_DEPCHECK([gcc gc gmp], [
     AC_PATH_PROG([ECL_CONFIG], [ecl-config])
     AS_IF([test x$ECL_CONFIG != x], [
       # "CPPFLAGS" is not a typo, the --cflags output from

build/pkgs/ecm/SPKG.rst

@@ -19,13 +19,6 @@ Upstream Contact
 
 -  ecm-discuss@lists.gforge.inria.fr (requires subscription)
 
-Dependencies
-------------
-
--  GMP/MPIR (Note: Python is \*not\* required for ordinary builds.)
--  GNU patch
-
-
 Special Update/Build Instructions
 ---------------------------------
 
@@ -47,11 +40,10 @@ Special Update/Build Instructions
    Note that this doesn't affect the packages' selection of processor-
    specific optimized [assembly] code.
    'spkg-install' already reads the settings from Sage's and also a
-   system-wide GMP / MPIR now, but doesn't (yet) use all of them.
+   system-wide GMP now, but doesn't (yet) use all of them.
    If SAGE_FAT_BINARY="yes", we should avoid too specific settings of
    "-mcpu=...", and perhaps pass a more generic "--host=..." to
-   'configure'. (MPIR honors '--enable-fat' to some extent, but this
-   option isn't used on anything other than x86 / x86_64.)
+   'configure'.
 
 -  We currently work around a linker bug on MacOS X 10.5 PPC (with
    GCC 4.2.1) which breaks 'configure' if debug symbols are enabled.

build/pkgs/ecm/spkg-configure.m4

@@ -1,12 +1,6 @@
 SAGE_SPKG_CONFIGURE([ecm], [
     m4_pushdef([SAGE_ECM_MINVER],[7.0.4])
-    AC_REQUIRE([SAGE_SPKG_CONFIGURE_GMP])
-    AC_MSG_CHECKING([installing gmp/mpir? ])
-    if test x$sage_spkg_install_mpir = xyes -o x$sage_spkg_install_gmp = xyes; then
-        AC_MSG_RESULT([yes; install ecm as well])
-        sage_spkg_install_ecm=yes
-    else
-        AC_MSG_RESULT([no. ])
+    SAGE_SPKG_DEPCHECK([gmp], [
         AC_CHECK_HEADER(ecm.h, [
             AX_ABSOLUTE_HEADER([ecm.h])
             if test x$gl_cv_absolute_ecm_h = x; then
@@ -38,6 +32,6 @@ SAGE_SPKG_CONFIGURE([ecm], [
             AS_IF([test -z "$ac_cv_ECM"], [sage_spkg_install_ecm=yes])
             AS_IF([test -z "$ac_cv_ECMBIN"], [sage_spkg_install_ecm=yes])
         ], [sage_spkg_install_ecm=yes])
-    fi
+    ])
     m4_popdef([SAGE_ECM_MINVER])
 ])

build/pkgs/fflas_ffpack/spkg-configure.m4

@@ -1,7 +1,5 @@
 SAGE_SPKG_CONFIGURE([fflas_ffpack], [
-  # fflas-lapack uses whatever multi-precision library givaro uses,
-  # either gmp or mpir.
-  SAGE_SPKG_DEPCHECK([givaro gmp mpir openblas], [
+  SAGE_SPKG_DEPCHECK([givaro gmp openblas], [
     # If our dependencies come from the system, then we can use
     # the system fflas-ffpack, too. Use pkg-config to find a
     # recentish version, if there is one.