From 9281217ffad338c3469a38feced75c407e34137d Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Tue, 4 Apr 2017 19:56:00 -0700
Subject: parser: bugfix: don't scan @NUM in QSPECIAL state.

The problem is syntax like `@@12a` being scanned
as if it were `@{@12}a` rather than @{@12a}`.

When the scanner is in the middle of a quasiliteral, in the
QSILIT state and sees a @, it transitions to the QSPECIAL
state.

In the QSPECIAL state, the METANUM token syntax is recognized
consisting of @ followed by a decimal, octal or hex number.

In the same QSPECIAL state, however, a meta-variable like @abc
is not recognized as a unit; rather, a @ is recognized by
itself, and abc by itself.  Thus when @12a is seen in the
QSPECIAL state, the @12 is the longest match.

The fix is to treat METANUM tokens the same way in the
QSPECIAL state: just recognize a number without the @
prefix, and report as a METANUM.

* parser.l (grammar): Split the pattern in all four
METANUM rules so that in the NESTED, BRACED,
QSLIT and QWLIT states, the number is recognized
together with the @ prefix. But in the QSPECIAL
state, indicating that one or more @ characters have
been seen, just recognize a number without the prefix
as a METANUM.
---
 parser.l | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/parser.l b/parser.l
index 2d2c11ea..cf6de7f0 100644
--- a/parser.l
+++ b/parser.l
@@ -336,7 +336,8 @@ UONLY   {U2}{U}|{U3}{U}{U}|{U4}{U}{U}{U}
   return NUMBER;
 }
 
-<NESTED,BRACED,QSILIT,QWLIT,QSPECIAL>@{NUM} {
+<NESTED,BRACED,QSILIT,QWLIT>@{NUM} |
+<QSPECIAL>{NUM} {
   val str = string_own(utf8_dup_from(yytext + 1));
 
   if (yy_top_state(yyscanner) == INITIAL
@@ -347,7 +348,8 @@ UONLY   {U2}{U}|{U3}{U}{U}|{U4}{U}{U}{U}
   return METANUM;
 }
 
-<NESTED,QSILIT,QWLIT,QSPECIAL>@{XNUM} {
+<NESTED,QSILIT,QWLIT>@{XNUM} |
+<QSPECIAL>{XNUM} {
   val str = string_own(utf8_dup_from(yytext + 3));
 
   if (yy_top_state(yyscanner) == INITIAL
@@ -358,7 +360,8 @@ UONLY   {U2}{U}|{U3}{U}{U}|{U4}{U}{U}{U}
   return METANUM;
 }
 
-<NESTED,QSILIT,QWLIT,QSPECIAL>@{ONUM} {
+<NESTED,QSILIT,QWLIT>@{ONUM} |
+<QSPECIAL>{ONUM} {
   val str = string_own(utf8_dup_from(yytext + 3));
 
   if (yy_top_state(yyscanner) == INITIAL
-- 
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