Re: escape hash mark

[Stefano Lattarini]

On Friday 19 August 2011, Daniel Neuberger wrote:
> Is there any way to reliable escape the hash mark in automake?  It seems 
> that using += causes multiple expansions and breaks it.
> 
> This works:
> 
> SOMEVAR = "\# some comment"
> 
> This doesn't
> 
> SOMEVAR = "\# some comment"
> SOMEVAR += "other stuff"
>
Yes, automake strips what seems like a trailing comment when concatenating
variables, to allow usages like:

  EXTRA_DIST = autogen.sh # Bootstrap the package from git checkout.
  EXTRA_DIST += HACKING   # Coding standards and hints for contributors.

> So my current workaround is:
> 
> HASHMARK = $(shell echo "\#")
> SOMEVAR = "$(HASHMARK)some comment"
> SOMEVAR += "other stuff"
>
Does the following works?

  HASHMARK = \#
  SOMEVAR = "$(HASHMARK)some comment"
  SOMEVAR += "other stuff"

Anyway, consider that there is no portable way to place a literal `#' in
a make variable; for example:

  $ cat > Makefile <<'END'
  foo = \# comment
  all:; @echo '$(foo)'
  END

  $ make # GNU and BSD make implementations work.
  # comment

  $ make # Solaris make does not.
  mksh: Fatal error in reader: Loop detected when expanding macro value `\# 
comment
  all:; @echo '$(foo)''
  Current working directory /tmp

  $ cat > Makefile <<'END' # Try in another way.
  bar = "#" comment
  all:; @echo x'$(bar)'x
  END
  $ make # Solaris make.
  x"x

HTH,
  Stefano