[Bug translation/79618] New: prevent missing space in multiline string literals

["roland.illig at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79618

            Bug ID: 79618
           Summary: prevent missing space in multiline string literals
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: translation
          Assignee: unassigned at gcc dot gnu.org
          Reporter: roland.illig at gmx dot de
  Target Milestone: ---

As demonstrated in #79610, #79612, #79613, #79614, #79615, #79616, #79617,
there are many chances for introducing missing spaces in multiline string
literals, which can even hide test cases, like in commit
138bc75d-0d04-0410-961f-82ee72b054a4.

To prevent this from ever happening again, there should be some automatic check
that detects these wrong string literals.

This test should currently find the word "cannot" in fortran/match.c, which is
split into two lines. No problem here, but it smells like one.

      if (group_name->attr.flavor == FL_NAMELIST
          && group_name->attr.use_assoc
          && !gfc_notify_std (GFC_STD_GNU, "Namelist group name %qs "
                              "at %C already is USE associated and can"
                              "not be respecified.", group_name->name))