config: make numeric parsing errors more clear

If we try to parse an integer config argument and get a
number outside of the representable range, we die with the
cryptic message: "bad config value for '%s'".

We can improve two things:

  1. Show the value that produced the error (e.g., bad
     config value '3g' for 'foo.bar').

  2. Mention the reason the value was rejected (e.g.,
     "invalid unit" versus "out of range").

A few tests need to be updated with the new output, but that
should not be representative of real-world breakage, as
scripts should not be depending on the exact text of our
stderr output, which is subject to i18n anyway.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -543,18 +543,25 @@ int git_parse_ulong(const char *value, unsigned long *ret)
 	return 1;
 }
 
-static void die_bad_config(const char *name)
+static void die_bad_number(const char *name, const char *value)
 {
+	const char *reason = errno == ERANGE ?
+			     "out of range" :
+			     "invalid unit";
+	if (!value)
+		value = "";
+
 	if (cf && cf->name)
-		die("bad config value for '%s' in %s", name, cf->name);
-	die("bad config value for '%s'", name);
+		die("bad numeric config value '%s' for '%s' in %s: %s",
+		    value, name, cf->name, reason);
+	die("bad numeric config value '%s' for '%s': %s", value, name, reason);
 }
 
 int git_config_int(const char *name, const char *value)
 {
 	int ret;
 	if (!git_parse_int(value, &ret))
-		die_bad_config(name);
+		die_bad_number(name, value);
 	return ret;
 }
 
@@ -562,7 +569,7 @@ unsigned long git_config_ulong(const char *name, const char *value)
 {
 	unsigned long ret;
 	if (!git_parse_ulong(value, &ret))
-		die_bad_config(name);
+		die_bad_number(name, value);
 	return ret;
 }
 

t/t1300-repo-config.sh

@@ -657,11 +657,11 @@ test_expect_success 'invalid unit' '
 	echo 1auto >expect &&
 	git config aninvalid.unit >actual &&
 	test_cmp expect actual &&
-	cat > expect <<-\EOF
-	fatal: bad config value for '\''aninvalid.unit'\'' in .git/config
+	cat >expect <<-\EOF
+	fatal: bad numeric config value '\''1auto'\'' for '\''aninvalid.unit'\'' in .git/config: invalid unit
 	EOF
 	test_must_fail git config --int --get aninvalid.unit 2>actual &&
-	test_cmp actual expect
+	test_i18ncmp expect actual
 '
 
 cat > expect << EOF

t/t4055-diff-context.sh

@@ -73,7 +73,7 @@ test_expect_success 'plumbing not affected' '
 test_expect_success 'non-integer config parsing' '
 	git config diff.context no &&
 	test_must_fail git diff 2>output &&
-	test_i18ngrep "bad config value" output
+	test_i18ngrep "bad numeric config value" output
 '
 
 test_expect_success 'negative integer config parsing' '