bug#28241: man page in r-minimal contains timestamp

[Ricardo Wurmus <rekado@elephly.net>]

Ricardo Wurmus <rekado@elephly.net> writes:

> The man page is created with a rule in “doc/Makefile.in”:
>
>      @$(HELP2MAN) --include=$(srcdir)/R.aux --no-info --output=R.1 \
>        --name="a language for data analysis and graphics" \
>        $(top_builddir)/bin/R
>
> “doc/R.aux” does not contain a timestamp, nor does the help output of R
> itself.  Is help2man to blame here?

help2man supports SOURCE_DATE_EPOCH and it does the right thing when it
is set.

--8<---------------cut here---------------start------------->8---
$ guix environment --ad-hoc r-minimal help2man
$ help2man --include=R-3.4.0/doc/R.aux --no-info --output foo.1 R
$ grep August foo.1
.TH R "1" "August 2017" "R version 3.4.0 (2017-04-21) -- "You Stupid Darkness"" "User Commands"

$ SOURCE_DATE_EPOCH=0 help2man --include=R-3.4.0/doc/R.aux --no-info --output foo.1 R
$ grep August foo.1
$ grep January foo.1
.TH R "1" "January 1970" "R version 3.4.0 (2017-04-21) -- "You Stupid Darkness"" "User Commands"
--8<---------------cut here---------------end--------------->8---

Is SOURCE_DATE_EPOCH not set at the time help2man runs?  “r-minimal”
uses the gnu-build-system, which has a build phase set-SOURCE-DATE-EPOCH
that sets SOURCE_DATE_EPOCH to 1.

Where is this lost?

-- 
Ricardo

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