From 02c72645fc9cb7436913351a509513f8e2d95c38 Mon Sep 17 00:00:00 2001
From: Kevin Stravers <kevin@stravers.net>
Date: Thu, 14 Mar 2024 13:47:25 -0400
Subject: [PATCH] Allow checking whether optionals provided explicitly

Since boolean optionals default to "off" we have no way to
check if a boolean optional was actually specified on the command line.

The ability to check if a boolean optional has been given is useful in
cases where we source values from a configuration file where we want any
explicitly given arguments to override the configuration.

An example that mostly works is (for plain optionals with an empty default):

        test -f ~/.standard-values-for-this-script && source "$_"
        MYOPT="${MYOPT:-$_arg_myopt}"
        ... # Code using MYOPT

This works since optionals can default to an empty string. We still are
not entirely sure if the optional was actually passed here, but it tends
to be "good enough" in most cases.

In the case where `myopt` is boolean, the above case would always use
"off" if the argument was not specified, thus overriding the sourced
configuration file.

This patch introduces `_optionals`, an array where each
optional inserts itself if they were actually given.

This allows us to do the following:

        test -f ~/.standard-values-for-this-script && source "$_"
        if [[ ${_optionals[@]} =~ _arg_myopt ]]; then
                MYOPT="$_arg_myopt" # We override
        fi
        ... # Code using MYOPT
---
 src/stuff.m4 | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/stuff.m4 b/src/stuff.m4
index 2a074b2..0c07dd8 100644
--- a/src/stuff.m4
+++ b/src/stuff.m4
@@ -444,6 +444,7 @@ dnl $5: Where to get the last value (optional)
 m4_define([_VAL_OPT_ADD_SPACE_WITHOUT_GETOPT_OR_SHORT_OPT], [_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 	[test $[]# -lt 2 && die "Missing value for the optional argument '$_key'." 1],
 	[$3([$1], ["@S|@2"], [$4])],
+	[_optionals+=($4)]
 	[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$4], [m4_default_quoted([$5], [@S|@2])])],
 	[shift],
 )])
@@ -458,6 +459,7 @@ dnl $5: Where to get the last value (optional)
 m4_define([_VAL_OPT_ADD_GETOPTS], [_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 	[test "$OPTARG" = "" && die "Missing value for the optional argument '-$_key'." 1],
 	[$3([$1], ["$OPTARG"], [$4])],
+	[_optionals+=($3)dnl]
 	[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$4], [m4_default_quoted([$5], [$OPTARG])])],
 )])
 
@@ -470,6 +472,7 @@ dnl $4: The name of the argument-holding variable
 dnl $5: Where to get the last value (optional)
 m4_define([_VAL_OPT_ADD_EQUALS_WITH_LONG_OPT], [_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 	[$3([$1], ["${_key##--$1=}"], [$4])],
+	[_optionals+=($4)dnl]
 	[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_EQUALS([$4])],
 )])
 
@@ -482,6 +485,7 @@ dnl $4: The name of the argument-holding variable
 dnl $5: Where to get the last value (optional)
 m4_define([_VAL_OPT_ADD_ONLY_WITH_SHORT_OPT_GETOPT], [_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 	[$3([$1], ["${_key##-$2}"], [$4])],
+	[_optionals+=($4)dnl]
 	[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_GETOPT([$4])],
 )])
 
@@ -731,12 +735,14 @@ m4_define([_MAKE_OPTARG_SIMPLE_CASE_SECTION], [m4_do(
 		[bool],
 		[_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 			[[$5="on"]],
+			[[_optionals+=($5)]],
 			[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$5])],
 			[[test "${1:0:5}" = "--no-" && $5="off"]],
 		)],
 		[incr],
 		[_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 			[[$5=$(($5 + 1))]],
+			[[_optionals+=($5)]],
 			[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$5])],
 		)],
 		[action],
@@ -763,11 +769,13 @@ m4_define([_MAKE_OPTARG_GETOPTS_CASE_SECTION], [m4_do(
 		[bool],
 		[_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 			[[$5="on"]],
+			[[_optionals+=($5)]],
 			[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$5])],
 		)],
 		[incr],
 		[_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 			[[$5=$(($5 + 1))]],
+			[[_optionals+=($5)]],
 			[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$5])],
 		)],
 		[action],
@@ -823,12 +831,14 @@ m4_define([_MAKE_OPTARG_GETOPT_CASE_SECTION], [m4_do(
 		[bool],
 		[_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 			[[$5="on"]],
+			[[_optionals+=($5)]],
 			_PASS_WHEN_GETOPT([$2]),
 			[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$5])],
 		)],
 		[incr],
 		[_JOIN_INDENTED(_INDENT_LEVEL_IN_ARGV_CASE_BODY,
 			[[$5=$(($5 + 1))]],
+			[[_optionals+=($5)]],
 			_PASS_WHEN_GETOPT([$2]),
 			[_APPEND_WRAPPED_ARGUMENT_TO_ARRAY_SPACE([$5])],
 		)],
@@ -1226,6 +1236,7 @@ m4_define([_MAKE_DEFAULTS_POSITIONAL_POSIX], [m4_do(
 
 m4_define([_MAKE_DEFAULTS_OPTIONAL], [m4_do(
 	[[# THE DEFAULTS INITIALIZATION - OPTIONALS]_ENDL_],
+	[[_optionals=()]_ENDL_],
 	[m4_lists_foreach_optional([_ARGS_LONG,_ARGS_CATH,_ARGS_DEFAULT,_ARGS_VARNAME], [_argname,_arg_type,_default,_arg_varname], [m4_do(
 		[dnl We have to handle 'incr' as a special case, there is a m4_default(..., 0)
 ],