Remove typedef celt from the regex library, along with macro NOCELT.

The regex library used to have a notion of a "collating element" that was
distinct from a "character", but Henry Spencer never actually implemented
his planned support for multi-character collating elements, and the Tcl
crew ripped out most of the stubs for that years ago.  The only thing left
that distinguished the "celt" typedef from the "chr" typedef was that
"celt" was supposed to also be able to hold the not-a-character "NOCELT"
value.  However, NOCELT was not used anywhere after the MCCE stub removal
changes, which means there's no need for celt to be different from chr.
Removing the separate typedef simplifies matters and also removes a trap
for the unwary, in that celt is signed while chr may not be, so comparisons
could mean different things.  There's no bug there today because we
restrict CHR_MAX to be less than INT_MAX, but I think there may have been
such bugs before we did that, and there could be again if anyone ever
decides to fool with the range of chr.

This patch also removes assorted unnecessary casts to "chr" of values
that are already chrs.  Many of these seem to be leftover from days when
the code was compatible with pre-ANSI C.

src/backend/regex/regc_cvec.c

@@ -78,7 +78,7 @@ addchr(struct cvec * cv,		/* character vector */
 	   chr c)					/* character to add */
 {
 	assert(cv->nchrs < cv->chrspace);
-	cv->chrs[cv->nchrs++] = (chr) c;
+	cv->chrs[cv->nchrs++] = c;
 }
 
 /*
@@ -90,8 +90,8 @@ addrange(struct cvec * cv,		/* character vector */
 		 chr to)				/* last character of range */
 {
 	assert(cv->nranges < cv->rangespace);
-	cv->ranges[cv->nranges * 2] = (chr) from;
-	cv->ranges[cv->nranges * 2 + 1] = (chr) to;
+	cv->ranges[cv->nranges * 2] = from;
+	cv->ranges[cv->nranges * 2 + 1] = to;
 	cv->nranges++;
 }
 

src/backend/regex/regc_lex.c

@@ -870,7 +870,7 @@ lexescape(struct vars * v)
 			if (v->now == save || ((int) c > 0 && (int) c <= v->nsubexp))
 			{
 				NOTE(REG_UBACKREF);
-				RETV(BACKREF, (chr) c);
+				RETV(BACKREF, c);
 			}
 			/* oops, doesn't look like it's a backref after all... */
 			v->now = save;
@@ -986,10 +986,8 @@ lexdigits(struct vars * v,
  */
 static int						/* 1 normal, 0 failure */
 brenext(struct vars * v,
-		chr pc)
+		chr c)
 {
-	chr			c = (chr) pc;
-
 	switch (c)
 	{
 		case CHR('*'):
@@ -1153,7 +1151,7 @@ chrnamed(struct vars * v,
 		 const chr *endp,		/* just past end of name */
 		 chr lastresort)		/* what to return if name lookup fails */
 {
-	celt		c;
+	chr			c;
 	int			errsave;
 	int			e;
 	struct cvec *cv;
@@ -1165,10 +1163,10 @@ chrnamed(struct vars * v,
 	v->err = errsave;
 
 	if (e != 0)
-		return (chr) lastresort;
+		return lastresort;
 
 	cv = range(v, c, c, 0);
 	if (cv->nchrs == 0)
-		return (chr) lastresort;
+		return lastresort;
 	return cv->chrs[0];
 }

src/backend/regex/regc_locale.c

@@ -361,9 +361,9 @@ static const struct cname
 
 
 /*
- * element - map collating-element name to celt
+ * element - map collating-element name to chr
  */
-static celt
+static chr
 element(struct vars * v,		/* context */
 		const chr *startp,		/* points to start of name */
 		const chr *endp)		/* points just past end of name */
@@ -401,13 +401,13 @@ element(struct vars * v,		/* context */
  */
 static struct cvec *
 range(struct vars * v,			/* context */
-	  celt a,					/* range start */
-	  celt b,					/* range end, might equal a */
+	  chr a,					/* range start */
+	  chr b,					/* range end, might equal a */
 	  int cases)				/* case-independent? */
 {
 	int			nchrs;
 	struct cvec *cv;
-	celt		c,
+	chr			c,
 				cc;
 
 	if (a != b && !before(a, b))
@@ -444,7 +444,7 @@ range(struct vars * v,			/* context */
 
 	for (c = a; c <= b; c++)
 	{
-		cc = pg_wc_tolower((chr) c);
+		cc = pg_wc_tolower(c);
 		if (cc != c &&
 			(before(cc, a) || before(b, cc)))
 		{
@@ -455,7 +455,7 @@ range(struct vars * v,			/* context */
 			}
 			addchr(cv, cc);
 		}
-		cc = pg_wc_toupper((chr) c);
+		cc = pg_wc_toupper(c);
 		if (cc != c &&
 			(before(cc, a) || before(b, cc)))
 		{
@@ -477,10 +477,10 @@ range(struct vars * v,			/* context */
 }
 
 /*
- * before - is celt x before celt y, for purposes of range legality?
+ * before - is chr x before chr y, for purposes of range legality?
  */
 static int						/* predicate */
-before(celt x, celt y)
+before(chr x, chr y)
 {
 	if (x < y)
 		return 1;
@@ -493,7 +493,7 @@ before(celt x, celt y)
  */
 static struct cvec *
 eclass(struct vars * v,			/* context */
-	   celt c,					/* Collating element representing the
+	   chr c,					/* Collating element representing the
 								 * equivalence class. */
 	   int cases)				/* all cases? */
 {
@@ -503,12 +503,12 @@ eclass(struct vars * v,			/* context */
 	if ((v->cflags & REG_FAKE) && c == 'x')
 	{
 		cv = getcvec(v, 4, 0);
-		addchr(cv, (chr) 'x');
-		addchr(cv, (chr) 'y');
+		addchr(cv, CHR('x'));
+		addchr(cv, CHR('y'));
 		if (cases)
 		{
-			addchr(cv, (chr) 'X');
-			addchr(cv, (chr) 'Y');
+			addchr(cv, CHR('X'));
+			addchr(cv, CHR('Y'));
 		}
 		return cv;
 	}
@@ -518,7 +518,7 @@ eclass(struct vars * v,			/* context */
 		return allcases(v, c);
 	cv = getcvec(v, 1, 0);
 	assert(cv != NULL);
-	addchr(cv, (chr) c);
+	addchr(cv, c);
 	return cv;
 }
 
@@ -673,15 +673,14 @@ cclass(struct vars * v,			/* context */
  */
 static struct cvec *
 allcases(struct vars * v,		/* context */
-		 chr pc)				/* character to get case equivs of */
+		 chr c)					/* character to get case equivs of */
 {
 	struct cvec *cv;
-	chr			c = (chr) pc;
 	chr			lc,
 				uc;
 
-	lc = pg_wc_tolower((chr) c);
-	uc = pg_wc_toupper((chr) c);
+	lc = pg_wc_tolower(c);
+	uc = pg_wc_toupper(c);
 
 	cv = getcvec(v, 2, 0);
 	addchr(cv, lc);

src/backend/regex/regcomp.c

@@ -210,10 +210,10 @@ static pg_wchar pg_wc_toupper(pg_wchar c);
 static pg_wchar pg_wc_tolower(pg_wchar c);
 
 /* === regc_locale.c === */
-static celt element(struct vars *, const chr *, const chr *);
-static struct cvec *range(struct vars *, celt, celt, int);
-static int	before(celt, celt);
-static struct cvec *eclass(struct vars *, celt, int);
+static chr	element(struct vars *, const chr *, const chr *);
+static struct cvec *range(struct vars *, chr, chr, int);
+static int	before(chr, chr);
+static struct cvec *eclass(struct vars *, chr, int);
 static struct cvec *cclass(struct vars *, const chr *, const chr *, int);
 static struct cvec *allcases(struct vars *, chr);
 static int	cmp(const chr *, const chr *, size_t);
@@ -1424,8 +1424,8 @@ brackpart(struct vars * v,
 		  struct state * lp,
 		  struct state * rp)
 {
-	celt		startc;
-	celt		endc;
+	chr			startc;
+	chr			endc;
 	struct cvec *cv;
 	const chr  *startp;
 	const chr  *endp;

src/include/regex/regcustom.h

@@ -58,15 +58,13 @@
 /* internal character type and related */
 typedef pg_wchar chr;			/* the type itself */
 typedef unsigned uchr;			/* unsigned type that will hold a chr */
-typedef int celt;				/* type to hold chr, or NOCELT */
 
-#define NOCELT	(-1)			/* celt value which is not valid chr */
 #define CHR(c)	((unsigned char) (c))	/* turn char literal into chr literal */
 #define DIGITVAL(c) ((c)-'0')	/* turn chr digit into its value */
 #define CHRBITS 32				/* bits in a chr; must not use sizeof */
 #define CHR_MIN 0x00000000		/* smallest and largest chr; the value */
 #define CHR_MAX 0x7ffffffe		/* CHR_MAX-CHR_MIN+1 must fit in an int, and
-								 * CHR_MAX+1 must fit in both chr and celt */
+								 * CHR_MAX+1 must fit in a chr variable */
 
 /*
  * Check if a chr value is in range.  Ideally we'd just write this as