fix argparse handling of short flag only specs

@faho noticed that option specs which don't have a long flag name are
not handled correctly. This fixes that and adds unit tests.

Fixes #4232

tests/argparse.err

@@ -29,6 +29,8 @@ argparse: Long flag 'short' already defined
 argparse: Implicit int flag '#' already defined
 # Defining an implicit int flag with modifiers
 argparse: Implicit int short flag 'v' does not allow modifiers like '='
+# Implicit int short flag only with custom validation fails
+argparse: Value '499' for flag 'x' less than min allowed of '500'
 # Implicit int flag validation fails
 argparse: Value '765x' for flag 'max' is not an integer
 argparse: Value 'a1' for flag 'm' is not an integer

tests/argparse.in

@@ -86,15 +86,42 @@ set -l
 for v in (set -l -n); set -e $v; end
 argparse 'v/verbose' '#-val' 't/token=' -- -123 a1 --token woohoo --234 -v a2 --verbose
 set -l
+
 echo '# Should be set to 987'
 for v in (set -l -n); set -e $v; end
 argparse 'm#max' -- argle -987 bargle
 set -l
+
 echo '# Should be set to 765'
 for v in (set -l -n); set -e $v; end
 argparse 'm#max' -- argle -987 bargle --max 765
 set -l
 
+echo '# Bool short flag only'
+for v in (set -l -n); set -e $v; end
+argparse 'C' 'v' -- -C -v arg1 -v arg2
+set -l
+
+echo '# Value taking short flag only'
+for v in (set -l -n); set -e $v; end
+argparse 'x=' 'v/verbose' -- --verbose arg1 -v -x arg2
+set -l
+
+echo '# Implicit int short flag only'
+for v in (set -l -n); set -e $v; end
+argparse 'x#' 'v/verbose' -- -v -v argle -v -x 321 bargle
+set -l
+
+echo '# Implicit int short flag only with custom validation passes'
+for v in (set -l -n); set -e $v; end
+argparse 'x#!_validate_int --max 500' 'v/verbose' -- -v -v -x 499 -v
+set -l
+
+echo '# Implicit int short flag only with custom validation fails' >&2
+for v in (set -l -n); set -e $v; end
+argparse 'x#!_validate_int --min 500' 'v/verbose' -- -v -v -x 499 -v
+set -l
+
 ##########
 # Verify that flag value validation works.
 

tests/argparse.out

@@ -38,6 +38,25 @@ argv 'argle'  'bargle'
 _flag_m 765
 _flag_max 765
 argv 'argle'  'bargle'
+# Bool short flag only
+_flag_C -C
+_flag_v '-v'  '-v'
+argv 'arg1'  'arg2'
+# Value taking short flag only
+_flag_v '--verbose'  '-v'
+_flag_verbose '--verbose'  '-v'
+_flag_x arg2
+argv arg1
+# Implicit int short flag only
+_flag_v '-v'  '-v'  '-v'
+_flag_verbose '-v'  '-v'  '-v'
+_flag_x 321
+argv 'argle'  'bargle'
+# Implicit int short flag only with custom validation passes
+_flag_v '-v'  '-v'  '-v'
+_flag_verbose '-v'  '-v'  '-v'
+_flag_x 499
+argv
 # Check the exit status from argparse validation
 _flag_name max
 _flag_value 83