Options: treat array option -Dopt= and -Dopt=[] as equivalent

Currently the former will be parsed as [''], while the latter is parsed
as [] in python. This makes for some obnoxious special handling
depending on what the user passes. This is even more obnoxious since for
string type arguments this doesn't require special handling.

2 files changed, 8 insertions, 0 deletions

diff --git a/docs/markdown/Build-options.md b/docs/markdown/Build-options.md
index 0093a1b..66c9cb5 100644
--- a/docs/markdown/Build-options.md
+++ b/docs/markdown/Build-options.md
@@ -61,6 +61,9 @@ empty. The `value` parameter specifies the default value of the option
 and if it is unset then the values of `choices` will be used as the
 default.
 
+As of 0.47.0 -Dopt= and -Dopt=[] both pass an empty list, before this -Dopt=
+would pass a list with an empty string.
+
 This type is available since version 0.44.0
 
 ### Features
diff --git a/docs/markdown/snippets/empty-array-opts.md b/docs/markdown/snippets/empty-array-opts.md
new file mode 100644
index 0000000..6d3b05d
--- /dev/null
+++ b/docs/markdown/snippets/empty-array-opts.md
@@ -0,0 +1,5 @@
+## Array options treat -Dopt= and -Dopt=[] as equivalent
+
+Prior to this change passing -Dopt= to an array opt would be interpreted as
+[''] (an array with an empty string), now -Dopt= is the same as -Dopt=[], an
+empty list.