sort: --debug: add warnings about sign, radix, and grouping chars

New warnings are added related to the handling
of thousands grouping characters, decimal points, and sign characters.
Examples now diagnosed are:

$ printf '0,9\n1,a\n' | sort -nk1 --debug -t, -s
sort: key 1 is numeric and spans multiple fields
sort: field separator ‘,’ is treated as a group separator in numbers
1,a
_
0,9
___

$ printf '1,a\n0,9\n' | LC_ALL=fr_FR.utf8 sort -gk1 --debug -t, -s
sort: key 1 is numeric and spans multiple fields
sort: field separator ‘,’ is treated as a decimal point in numbers
0,9
___
1,a
__

$ printf '1.0\n0.9\n' | LC_ALL=fr_FR.utf8 sort -s -k1,1g --debug
sort: note numbers use ‘,’ as a decimal point in this locale
0.9
_
1.0
_

$ LC_ALL=fr_FR.utf8 sort -n --debug /dev/null
sort: text ordering performed using ‘fr_FR.utf8’ sorting rules
sort: note numbers use ‘,’ as a decimal point in this locale
sort: the multi-byte number group separator in this locale \
      is not supported

$ sort --debug -t- -k1n /dev/null
sort: key 1 is numeric and spans multiple fields
sort: field separator ‘-’ is treated as a minus sign in numbers
sort: note numbers use ‘.’ as a decimal point in this locale

$ sort --debug -t+ -k1g /dev/null
sort: key 1 is numeric and spans multiple fields
sort: field separator ‘+’ is treated as a plus sign in numbers
sort: note numbers use ‘.’ as a decimal point in this locale

* src/sort.c (key_warnings): Add the warnings above.
* tests/misc/sort-debug-warn.sh: Add test cases.
Also check that all sort invocations succeed.
* NEWS: Mention the improvement.
Addresses https://bugs.gnu.org/51011

tests/misc/sort-debug-warn.sh

@@ -26,30 +26,39 @@ sort: key 1 has zero width and will be ignored
 2
 sort: text ordering performed using simple byte comparison
 sort: key 1 has zero width and will be ignored
+sort: note numbers use '.' as a decimal point in this locale
 3
 sort: text ordering performed using simple byte comparison
 sort: key 1 is numeric and spans multiple fields
+sort: note numbers use '.' as a decimal point in this locale
 4
 sort: text ordering performed using simple byte comparison
+sort: note numbers use '.' as a decimal point in this locale
 sort: options '-bghMRrV' are ignored
 5
 sort: text ordering performed using simple byte comparison
+sort: note numbers use '.' as a decimal point in this locale
 sort: options '-bghMRV' are ignored
 sort: option '-r' only applies to last-resort comparison
 6
 sort: text ordering performed using simple byte comparison
+sort: note numbers use '.' as a decimal point in this locale
 sort: option '-r' only applies to last-resort comparison
 7
 sort: text ordering performed using simple byte comparison
 sort: leading blanks are significant in key 2; consider also specifying 'b'
+sort: note numbers use '.' as a decimal point in this locale
 sort: options '-bg' are ignored
 8
 sort: text ordering performed using simple byte comparison
+sort: note numbers use '.' as a decimal point in this locale
 9
 sort: text ordering performed using simple byte comparison
+sort: note numbers use '.' as a decimal point in this locale
 sort: option '-b' is ignored
 10
 sort: text ordering performed using simple byte comparison
+sort: note numbers use '.' as a decimal point in this locale
 11
 sort: text ordering performed using simple byte comparison
 sort: leading blanks are significant in key 1; consider also specifying 'b'
@@ -73,40 +82,39 @@ sort: text ordering performed using simple byte comparison
 EOF
 
 echo 1 >> out
-sort -s -k2,1 --debug /dev/null 2>>out
+sort -s -k2,1 --debug /dev/null 2>>out || fail=1
 echo 2 >> out
-sort -s -k2,1n --debug /dev/null 2>>out
+sort -s -k2,1n --debug /dev/null 2>>out || fail=1
 echo 3 >> out
-sort -s -k1,2n --debug /dev/null 2>>out
+sort -s -k1,2n --debug /dev/null 2>>out || fail=1
 echo 4 >> out
-sort -s -rRVMhgb -k1,1n --debug /dev/null 2>>out
+sort -s -rRVMhgb -k1,1n --debug /dev/null 2>>out || fail=1
 echo 5 >> out
-sort -rRVMhgb -k1,1n --debug /dev/null 2>>out
+sort -rRVMhgb -k1,1n --debug /dev/null 2>>out || fail=1
 echo 6 >> out
-sort -r -k1,1n --debug /dev/null 2>>out
+sort -r -k1,1n --debug /dev/null 2>>out || fail=1
 echo 7 >> out
-sort -gbr -k1,1n -k1,1r --debug /dev/null 2>>out
+sort -gbr -k1,1n -k1,1r --debug /dev/null 2>>out || fail=1
 echo 8 >> out
-sort -b -k1b,1bn --debug /dev/null 2>>out # no warning
+sort -b -k1b,1bn --debug /dev/null 2>>out || fail=1 # no warning
 echo 9 >> out
-sort -b -k1,1bn --debug /dev/null 2>>out
+sort -b -k1,1bn --debug /dev/null 2>>out || fail=1
 echo 10 >> out
-sort -b -k1,1bn -k2b,2 --debug /dev/null 2>>out # no warning
+sort -b -k1,1bn -k2b,2 --debug /dev/null 2>>out || fail=1 # no warning
 echo 11 >> out
-sort -r -k1,1r --debug /dev/null 2>>out # no warning for redundant options
+sort -r -k1,1r --debug /dev/null 2>>out || fail=1 # no warning for redundant opt
 echo 12 >> out
-sort -i -k1,1i --debug /dev/null 2>>out # no warning
+sort -i -k1,1i --debug /dev/null 2>>out || fail=1 # no warning
 echo 13 >> out
-sort -d -k1,1b --debug /dev/null 2>>out
+sort -d -k1,1b --debug /dev/null 2>>out || fail=1
 echo 14 >> out
-sort -i -k1,1d --debug /dev/null 2>>out
+sort -i -k1,1d --debug /dev/null 2>>out || fail=1
 echo 15 >> out
-sort -r --debug /dev/null 2>>out #no warning
+sort -r --debug /dev/null 2>>out || fail=1 #no warning
 echo 16 >> out
-sort -rM --debug /dev/null 2>>out #no warning
+sort -rM --debug /dev/null 2>>out || fail=1 #no warning
 echo 17 >> out
-sort -rM -k1,1 --debug /dev/null 2>>out #no warning
-
+sort -rM -k1,1 --debug /dev/null 2>>out || fail=1 #no warning
 compare exp out || fail=1
 
 
@@ -114,9 +122,7 @@ cat <<\EOF > exp
 sort: failed to set locale
 sort: text ordering performed using simple byte comparison
 EOF
-
-LC_ALL=missing sort --debug /dev/null 2>out
-
+LC_ALL=missing sort --debug /dev/null 2>out || fail=1
 # musl libc maps unknown locales to the default utf8 locale
 # with no way to determine failures.  This is discussed at:
 # http://www.openwall.com/lists/musl/2016/04/02/1
@@ -130,12 +136,50 @@ sort: text ordering performed using simple byte comparison
 sort: key 1 is numeric and spans multiple fields
 sort: obsolescent key '+2 -1' used; consider '-k 3,1' instead
 sort: key 2 has zero width and will be ignored
+sort: note numbers use '.' as a decimal point in this locale
 sort: option '-b' is ignored
 sort: option '-r' only applies to last-resort comparison
 EOF
+sort --debug -rb -k2n +2.2 -1b /dev/null 2>out || fail=1
+compare exp out || fail=1
 
-sort --debug -rb -k2n +2.2 -1b /dev/null 2>out
 
+# check sign, decimal point, and grouping character warnings
+cat <<\EOF > exp
+sort: text ordering performed using simple byte comparison
+sort: key 1 is numeric and spans multiple fields
+sort: field separator ',' is treated as a group separator in numbers
+EOF
+if test $(printf '0,9\n0,8\n' | sort -ns | tail -n1) = '0,9'; then
+  # thousands_sep == ,
+  sort -nk1 -t, --debug /dev/null 2>out || fail=1
+  compare exp out || fail=1
+fi
+
+cat <<\EOF > exp
+sort: text ordering performed using simple byte comparison
+sort: key 1 is numeric and spans multiple fields
+sort: field separator '.' is treated as a decimal point in numbers
+EOF
+sort -nk1 -t. --debug /dev/null 2>out || fail=1
+compare exp out || fail=1
+
+cat <<\EOF > exp
+sort: text ordering performed using simple byte comparison
+sort: key 1 is numeric and spans multiple fields
+sort: field separator '-' is treated as a minus sign in numbers
+sort: note numbers use '.' as a decimal point in this locale
+EOF
+sort -nk1 -t- --debug /dev/null 2>out || fail=1
+compare exp out || fail=1
+
+cat <<\EOF > exp
+sort: text ordering performed using simple byte comparison
+sort: key 1 is numeric and spans multiple fields
+sort: field separator '+' is treated as a plus sign in numbers
+sort: note numbers use '.' as a decimal point in this locale
+EOF
+sort -gk1 -t+ --debug /dev/null 2>out || fail=1
 compare exp out || fail=1
 
 Exit $fail