From 8130fcae5f65bbc749459a91a3790a2e82e63b7b Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Mon, 10 Aug 2015 22:33:48 -0700
Subject: Diagnose ambiguous floats like (a b).4 and x.y.5

These look like integers involved in qref dot syntax.

* parser.l (DOTFLO): New pattern definition.
(grammar): New rules for detecting cramped floating
literals.
---
 parser.l | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/parser.l b/parser.l
index dc083867..59189385 100644
--- a/parser.l
+++ b/parser.l
@@ -176,6 +176,7 @@ XDIG    [0-9A-Fa-f]
 NUM     {SGN}?{DIG}+
 FLO     {SGN}?({DIG}*[.]{DIG}+{EXP}?|{DIG}+[.]?{EXP})
 FLODOT  {SGN}?{DIG}+[.]
+DOTFLO  [.]{DIG}+
 XNUM    #x{SGN}?{XDIG}+
 ONUM    #o{SGN}?[0-7]+
 BNUM    #b{SGN}?[0-1]+
@@ -355,6 +356,22 @@ UONLY   {U2}{U}|{U3}{U}{U}|{U4}{U}{U}{U}
   return METANUM;
 }
 
+<SPECIAL,QSPECIAL>{TOK}/{DOTFLO} |
+<BRACED>{BTOK}/{DOTFLO} |
+<NESTED>{NTOK}/{DOTFLO} {
+  yyerrorf(yyg, lit("cramped floating-point literal: "
+                    "add 0 or whitespace"), nao);
+
+  if (yy_top_state(yyscanner) == INITIAL
+      || yy_top_state(yyscanner) == QSILIT
+      || yy_top_state(yyscanner) == QWLIT)
+    yy_pop_state(yyscanner);
+
+  yylval->lexeme = utf8_dup_from(yytext);
+  return SYMTOK;
+}
+
+
 <SPECIAL,QSPECIAL>{TOK} |
 <BRACED>{BTOK} |
 <NESTED>{NTOK} {
@@ -584,6 +601,19 @@ UONLY   {U2}{U}|{U3}{U}{U}|{U4}{U}{U}{U}
   return yytext[0];
 }
 
+<SPECIAL,QSPECIAL,NESTED>[)\]]/{DOTFLO} {
+  yyerrorf(yyg, lit("cramped floating-point literal: "
+                    "add 0 or whitespace"), nao);
+
+  yy_pop_state(yyscanner);
+  if (yy_top_state(yyscanner) == INITIAL
+      || yy_top_state(yyscanner) == QSILIT
+      || yy_top_state(yyscanner) == QWLIT)
+    yy_pop_state(yyscanner);
+  return yytext[0];
+}
+
+
 <SPECIAL,QSPECIAL,NESTED>[)\]] {
   yy_pop_state(yyscanner);
   if (yy_top_state(yyscanner) == INITIAL
-- 
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