bug#46055: [PATCH] Add rust lang to etags

[Stefan Kangas <stefan@marxist.se>]

Your patch looks good to me, but I didn't test it.

I have one question, though.  In "test/manual/etags", we have manual
tests for etags including source code examples and which tags they
should generate.  Should we add a manual test also for Rust?

Pierre-Antoine Rouby <contact@parouby.fr> writes:

> * lib-src/etags.c (Rust_functions): New function to make tags for rust
> files.
>   (Rust_help, Rust_suffixes): New constant.
> * doc/emacs/maintaining.texi (Tag Syntax): Add Rust item.
> * doc/man/etags.1: Add Rust.
> ---
>  doc/emacs/maintaining.texi |  4 +++
>  doc/man/etags.1            |  2 +-
>  lib-src/etags.c            | 51 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 56 insertions(+), 1 deletion(-)
>
> diff --git a/doc/emacs/maintaining.texi b/doc/emacs/maintaining.texi
> index 415815473e..0f96dc65d1 100644
> --- a/doc/emacs/maintaining.texi
> +++ b/doc/emacs/maintaining.texi
> @@ -2639,6 +2639,10 @@ Tag Syntax
>  @item
>  In Ruby code, @code{def} or @code{class} or @code{module} at the
>  beginning of a line generate a tag.  Constants also generate tags.
> +
> +@item
> +In Rust code, tags anything defined with @code{fn}, @code{enum},
> +@code{struct} or @code{macro_rules!}.
>  @end itemize
>
>    You can also generate tags based on regexp matching (@pxref{Etags
> diff --git a/doc/man/etags.1 b/doc/man/etags.1
> index c5c15fb182..354f6ca88b 100644
> --- a/doc/man/etags.1
> +++ b/doc/man/etags.1
> @@ -51,7 +51,7 @@ format understood by
>  \&.  Both forms of the program understand
>  the syntax of C, Objective C, C++, Java, Fortran, Ada, Cobol, Erlang,
>  Forth, Go, HTML, LaTeX, Emacs Lisp/Common Lisp, Lua, Makefile, Pascal, Perl,
> -Ruby, PHP, PostScript, Python, Prolog, Scheme and
> +Ruby, Rust, PHP, PostScript, Python, Prolog, Scheme and
>  most assembler\-like syntaxes.
>  Both forms read the files specified on the command line, and write a tag
>  table (defaults: \fBTAGS\fP for \fBetags\fP, \fBtags\fP for
> diff --git a/lib-src/etags.c b/lib-src/etags.c
> index b5c18e0e01..d703183cef 100644
> --- a/lib-src/etags.c
> +++ b/lib-src/etags.c
> @@ -366,6 +366,7 @@ #define xrnew(op, n, m) ((op) = xnrealloc (op, n, (m) * sizeof *(op)))
>  static void Prolog_functions (FILE *);
>  static void Python_functions (FILE *);
>  static void Ruby_functions (FILE *);
> +static void Rust_entries (FILE *);
>  static void Scheme_functions (FILE *);
>  static void TeX_commands (FILE *);
>  static void Texinfo_nodes (FILE *);
> @@ -752,6 +753,12 @@ #define STDIN 0x1001		/* returned by getopt_long on --parse-stdin */
>  static const char *Ruby_interpreters [] =
>    { "ruby", NULL };
>
> +static const char *Rust_suffixes [] =
> +  { "rs", NULL };
> +static const char Rust_help [] =
> +  "In Rust code, tags anything defined with 'fn', 'enum', \n\
> +'struct' or 'macro_rules!'.";
> +
>  /* Can't do the `SCM' or `scm' prefix with a version number. */
>  static const char *Scheme_suffixes [] =
>    { "oak", "sch", "scheme", "SCM", "scm", "SM", "sm", "ss", "t", NULL };
> @@ -836,6 +843,7 @@ #define STDIN 0x1001		/* returned by getopt_long on --parse-stdin */
>                   NULL,           Python_interpreters },
>    { "ruby",      Ruby_help,      Ruby_functions,    Ruby_suffixes,
>                   Ruby_filenames, Ruby_interpreters },
> +  { "rust",      Rust_help,      Rust_entries,      Rust_suffixes      },
>    { "scheme",    Scheme_help,    Scheme_functions,  Scheme_suffixes    },
>    { "tex",       TeX_help,       TeX_commands,      TeX_suffixes       },
>    { "texinfo",   Texinfo_help,   Texinfo_nodes,     Texinfo_suffixes   },
> @@ -5019,6 +5027,49 @@ Ruby_functions (FILE *inf)
>      }
>  }
>
> +\f
> +/*
> + * Rust support
> + * Look for:
> + *  - fn: Function
> + *  - struct: Structure
> + *  - enum: Enumeration
> + *  - macro_rules!: Macro
> + */
> +static void
> +Rust_entries (FILE *inf)
> +{
> +  char *cp, *name;
> +  bool is_func = false;
> +
> +  LOOP_ON_INPUT_LINES(inf, lb, cp)
> +    {
> +      cp = skip_spaces(cp);
> +      name = cp;
> +
> +      // Skip 'pub' keyworld
> +      (void)LOOKING_AT (cp, "pub");
> +
> +      // Look for define
> +      if ((is_func = LOOKING_AT (cp, "fn"))
> +	  || LOOKING_AT (cp, "enum")
> +	  || LOOKING_AT (cp, "struct")
> +	  || (is_func = LOOKING_AT (cp, "macro_rules!")))
> +	{
> +	  cp = skip_spaces (cp);
> +	  name = cp;
> +
> +	  while (!notinname (*cp))
> +	    cp++;
> +
> +	  make_tag (name, cp - name, is_func,
> +		    lb.buffer, cp - lb.buffer + 1,
> +		    lineno, linecharno);
> +	  is_func = false;
> +	}
> +    }
> +}
> +
>  \f
>  /*
>   * PHP support