Make regular-expression error messages a tad less obscure,

per gripe from Josh Berkus.

src/backend/regex/regerror.c

@@ -59,10 +59,11 @@ static struct rerr
 
 {
 	{
-		REG_NOMATCH, "REG_NOMATCH", "regexec() failed to match"
+		/* NOMATCH is not really an error condition, it just says no match */
+		REG_NOMATCH, "REG_NOMATCH", "no pattern match found"
 	},
 	{
-		REG_BADPAT, "REG_BADPAT", "invalid regular expression"
+		REG_BADPAT, "REG_BADPAT", "invalid regex struct"
 	},
 	{
 		REG_ECOLLATE, "REG_ECOLLATE", "invalid collating element"
@@ -77,28 +78,28 @@ static struct rerr
 		REG_ESUBREG, "REG_ESUBREG", "invalid backreference number"
 	},
 	{
-		REG_EBRACK, "REG_EBRACK", "brackets ([ ]) not balanced"
+		REG_EBRACK, "REG_EBRACK", "brackets [ ] not balanced"
 	},
 	{
-		REG_EPAREN, "REG_EPAREN", "parentheses not balanced"
+		REG_EPAREN, "REG_EPAREN", "parentheses ( ) not balanced"
 	},
 	{
-		REG_EBRACE, "REG_EBRACE", "braces not balanced"
+		REG_EBRACE, "REG_EBRACE", "braces { } not balanced"
 	},
 	{
-		REG_BADBR, "REG_BADBR", "invalid repetition count(s)"
+		REG_BADBR, "REG_BADBR", "invalid repetition count(s) in { }"
 	},
 	{
-		REG_ERANGE, "REG_ERANGE", "invalid character range"
+		REG_ERANGE, "REG_ERANGE", "invalid character range in [ ]"
 	},
 	{
-		REG_ESPACE, "REG_ESPACE", "out of memory"
+		REG_ESPACE, "REG_ESPACE", "ran out of memory"
 	},
 	{
-		REG_BADRPT, "REG_BADRPT", "repetition-operator operand invalid"
+		REG_BADRPT, "REG_BADRPT", "?, *, or + operand invalid"
 	},
 	{
-		REG_EMPTY, "REG_EMPTY", "empty (sub)expression"
+		REG_EMPTY, "REG_EMPTY", "empty expression or subexpression"
 	},
 	{
 		REG_ASSERT, "REG_ASSERT", "\"can't happen\" -- you found a bug"

src/backend/regex/regex.3

@@ -464,11 +464,11 @@ include the following:
 .PP
 .nf
 .ta \w'REG_ECOLLATE'u+3n
-REG_NOMATCH	regexec() failed to match
-REG_BADPAT	invalid regular expression
+REG_NOMATCH	no pattern match found
+REG_BADPAT	invalid regex struct
 REG_ECOLLATE	invalid collating element
 REG_ECTYPE	invalid character class
-REG_EESCAPE	\e applied to unescapable character
+REG_EESCAPE	trailing backslash (\e)
 REG_ESUBREG	invalid backreference number
 REG_EBRACK	brackets [ ] not balanced
 REG_EPAREN	parentheses ( ) not balanced
@@ -477,7 +477,7 @@ REG_BADBR	invalid repetition count(s) in { }
 REG_ERANGE	invalid character range in [ ]
 REG_ESPACE	ran out of memory
 REG_BADRPT	?, *, or + operand invalid
-REG_EMPTY	empty (sub)expression
+REG_EMPTY	empty expression or subexpression
 REG_ASSERT	``can't happen''\(emyou found a bug
 REG_INVARG	invalid argument, e.g. negative-length string
 .fi

src/backend/utils/adt/regexp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.34 2001/01/24 19:43:14 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.35 2001/03/19 22:27:46 tgl Exp $
  *
  *		Alistair Crooks added the code for the regex caching
  *		agc - cached the regular expressions used - there's a good chance
@@ -140,7 +140,7 @@ RE_compile_and_execute(text *text_re, char *text, int cflags)
 		/* re didn't compile */
 		pg95_regerror(regcomp_result, &rev[oldest].cre_re, errMsg,
 					  sizeof(errMsg));
-		elog(ERROR, "regcomp failed with error %s", errMsg);
+		elog(ERROR, "Invalid regular expression: %s", errMsg);
 	}
 
 	/* not reached */