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Re: %nterm directive incorrectly accepts character literals and quoted s

From: Akim Demaille
Subject: Re: %nterm directive incorrectly accepts character literals and quoted strings
Date: Mon, 15 Oct 2018 20:26:35 +0200

Hi Rici!

> Le 15 oct. 2018 à 18:02, Rici Lake <address@hidden> a écrit :
> I only just noticed that %nterm is a bison directive, although I still
> don't fully understand the motivation. I can't find any reference in the
> manual, except for its unexplained use in one example. But Akim assures me
> that it has been accepted for quite some time, at least since 1993.
> […]

Thanks for the full analysis!

My personal opinion is that, yes, it seems nice, but it was not
exposed.  Well, this is not entirely true: I recently had it leak
in the documentation.  I did not do it intentionally, it just escaped.
It turns out that I do like its symmetry with %token (you didn’t
report that they have the same length, which I concede is really a
minor point, but I liked that things stay aligned :).

The first thing is to stop promoting it.  This patch does it:

commit c69944ff8b31c61dd4cfced84ebc95670cc4f31c
Author: Akim Demaille <address@hidden>
Date:   Mon Oct 15 19:22:40 2018 +0200

    doc: do not advertise %nterm
    Reported by Rici Lake.
    * NEWS, doc/bison.texi: here.

diff --git a/NEWS b/NEWS
index 7a039021..d8a21e53 100644
--- a/NEWS
+++ b/NEWS
@@ -26,8 +26,8 @@ GNU Bison NEWS
     %token <int> INT "int";
-    %nterm <std::unique_ptr<int>> int;
-    %nterm <std::vector<std::unique_ptr<int>>> list;
+    %type <std::unique_ptr<int>> int;
+    %type <std::vector<std::unique_ptr<int>>> list;
       %empty    {}
diff --git a/doc/bison.texi b/doc/bison.texi
index f633f1c9..3fddfe50 100644
--- a/doc/bison.texi
+++ b/doc/bison.texi
@@ -9198,11 +9198,11 @@ The following grammar file, @file{calc.y}, will be used 
in the sequel:
 @end group
 %token <ival> NUM
-%nterm <ival> exp
+%type  <ival> exp
 @end group
 %token <sval> STR
-%nterm <sval> useless
+%type  <sval> useless
 @end group
 %left '+' '-'

Then we should think what we want to do.  I like the way you
change the grammar to make it more consistent.

FWIW, I want to get 3.2 published asap, so I don’t plan to start
the changes in master right now.  That will be fine in 3.3.

AFAICT, 3.2 will be finished when I’m done with deprecated
files (https://lists.gnu.org/archive/html/bison-patches/2018-10/msg00065.html)
and with the default action made explicit

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