Add unity block size option.

2 files changed, 13 insertions, 0 deletions

diff --git a/docs/markdown/Builtin-options.md b/docs/markdown/Builtin-options.md
index 9eac371..067966f 100644
--- a/docs/markdown/Builtin-options.md
+++ b/docs/markdown/Builtin-options.md
@@ -82,6 +82,7 @@ Using the option as-is with no prefix affects all machines. For example:
 | stdsplit                             | true          | Split stdout and stderr in test logs                           | no             |
 | strip                                | false         | Strip targets on install                                       | no             |
 | unity {on, off, subprojects}         | off           | Unity build                                                    | no             |
+| unity_size {>=2}                     | 4             | Unity file block size                                          | no             |
 | warning_level {0, 1, 2, 3}           | 1             | Set the warning level. From 0 = none to 3 = highest            | no             |
 | werror                               | false         | Treat warnings as errors                                       | no             |
 | wrap_mode {default, nofallback,<br>nodownload, forcefallback} | default | Wrap mode to use                            | no             |
diff --git a/docs/markdown/snippets/unitysize.md b/docs/markdown/snippets/unitysize.md
new file mode 100644
index 0000000..4919ce0
--- /dev/null
+++ b/docs/markdown/snippets/unitysize.md
@@ -0,0 +1,12 @@
+## Unity file block size is configurable
+
+Traditionally the unity files that Meson autogenerates contain all
+source files that belong to a single target. This is the most
+efficient setting for full builds but makes incremental builds slow.
+This release adds a new option `unity_size` which specifies how many
+source files should be put in each unity file.
+
+The default value for block size is 4. This means that if you have a
+target that has eight source files, Meson will generate two unity
+files each of which includes four source files. The old behaviour can
+be replicated by setting `unity_size` to a large value, such as 10000.