bug#46052: Colons fooling GNUmakefile mode

[Kévin Le Gouguec]

Eli Zaretskii <eliz@gnu.org> writes:

> I'm not sure a target line cannot possibly start with a TAB.

I'll admit to not being an expert in makefile syntax; I do find this
entry in (info "(make) Error Messages") encouraging though:

> 'recipe commences before first target. Stop.'
> 'missing rule before recipe. Stop.'
>      This means the first thing in the makefile seems to be part of a
>      recipe: it begins with a recipe prefix character and doesn't appear
>      to be a legal 'make' directive (such as a variable assignment).
>      Recipes must always be associated with a target.

While that phrasing doesn't rule out subsequent targets from starting
with a TAB, empirically that seems to be the case:

#+begin_src makefile
foo:
        echo foo

        bar:
        echo bar
#+end_src

$ make
echo foo
foo
bar:
make: bar:: No such file or directory
make: *** [makefile:3: foo] Error 127

#+begin_src makefile
foo:
        echo foo

QUUX = CORGE

        bar:
        echo bar
#+end_src

$ make
makefile:6: *** recipe commences before first target.  Stop.