Fix bootstrap parser so that its keywords are unreserved words.

Mark Dilger pointed out that the bootstrap parser does not allow
any of its keywords to appear as column values unless they're quoted,
and proposed dealing with that by quoting such values in genbki.pl.
Looking closer, though, we also have that problem with respect to table,
column, and type names appearing in the .bki file: the parser would fail
if any of those matched any of its keywords.  While so far there have
been no conflicts (that I've heard of), this seems like a booby trap
waiting to catch somebody.  Rather than clutter genbki.pl with enough
quoting logic to handle all that, let's make the bootstrap parser grow
up a little bit and treat its keywords as unreserved.

Experimentation shows that it's fairly easy to do so with the exception
of _null_, which I don't have a big problem with keeping as a reserved
word.  The only change needed is that we can't have the "close" command
take an optional table name: it has to either require or forbid the
table name to avoid shift/reduce conflicts.  genbki.pl has historically
always included the table name, so I took that option.

The implementation has bootscanner.l passing forward the string value
of each keyword, in case bootparse.y needs that.  This avoids needing to
know the precise spelling of each keyword in bootparse.y, which is good
because that's not always obvious from the token name.

Discussion: https://postgr.es/m/3024FC91-DB6D-4732-B31C-DF772DF039A0@gmail.com

1 files changed, 7 insertions, 5 deletions

diff --git a/doc/src/sgml/bki.sgml b/doc/src/sgml/bki.sgml
index 5b557ffb7bf..e3ba73a9a8d 100644
--- a/doc/src/sgml/bki.sgml
+++ b/doc/src/sgml/bki.sgml
@@ -248,6 +248,8 @@
     <listitem>
      <para>
       Null values are represented by <literal>_null_</literal>.
+      (Note that there is no way to create a value that is just that
+      string.)
      </para>
     </listitem>
 
@@ -752,13 +754,13 @@ $ perl  rewrite_dat_with_prokind.pl  pg_proc.dat
 
    <varlistentry>
     <term>
-     <literal>close</literal> <optional><replaceable class="parameter">tablename</replaceable></optional>
+     <literal>close</literal> <replaceable class="parameter">tablename</replaceable>
     </term>
 
     <listitem>
      <para>
-      Close the open table.  The name of the table can be given as a
-      cross-check, but this is not required.
+      Close the open table.  The name of the table must be given as a
+      cross-check.
      </para>
     </listitem>
    </varlistentry>
@@ -782,8 +784,8 @@ $ perl  rewrite_dat_with_prokind.pl  pg_proc.dat
 
      <para>
       NULL values can be specified using the special key word
-      <literal>_null_</literal>.  Values containing spaces must be
-      double quoted.
+      <literal>_null_</literal>.  Values that do not look like
+      identifiers or digit strings must be double quoted.
      </para>
     </listitem>
    </varlistentry>