Mesa (master): meson: remove "empty array"/"array of an empty string" confusion

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Module: Mesa
Branch: master
Commit: d32144602c1dfd507f07774ce906dc25d2697da0
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d32144602c1dfd507f07774ce906dc25d2697da0

Author: Eric Engestrom <eric at engestrom.ch>
Date:   Mon May 14 16:40:47 2018 +0100

meson: remove "empty array"/"array of an empty string" confusion

Until Meson 0.47, setting `-D arrayoption=` was not the same as setting
`-D arrayoption=[]`; the latter cleared the array, while the former
filled it with an empty string option.

Since Meson 0.47 [1], the former maps to the latter, so empty items can
only be set by explicitly giving an array containing an empty string,
ie. `-D arrayoption="['']"`; however note that this is *not* what we
want in any of the current Mesa code anyway.

This makes the code handling array options a bit more complicated, and
a lot more error-prone, so let's get rid of the confusion by removing
the empty-string option.

[1] https://github.com/mesonbuild/meson/commit/f3a8f9c34d95d862fb4d12869a7b31cea592561f

Signed-off-by: Eric Engestrom <eric at engestrom.ch>
Reviewed-by: Dylan Baker <dylan at pnwbakers.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/386>

---

 meson.build       | 20 +++++++-------------
 meson_options.txt |  8 ++++----
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/meson.build b/meson.build
index 8d89bf9781e..1932410fcf7 100644
--- a/meson.build
+++ b/meson.build
@@ -181,7 +181,7 @@ with_dri_r200 = dri_drivers.contains('r200')
 with_dri_nouveau = dri_drivers.contains('nouveau')
 with_dri_swrast = dri_drivers.contains('swrast')
 
-with_dri = dri_drivers.length() != 0 and dri_drivers != ['']
+with_dri = dri_drivers.length() != 0
 
 gallium_drivers = get_option('gallium-drivers')
 if gallium_drivers.contains('auto')
@@ -228,7 +228,7 @@ with_gallium_swr = gallium_drivers.contains('swr')
 with_gallium_lima = gallium_drivers.contains('lima')
 with_gallium_zink = gallium_drivers.contains('zink')
 
-with_gallium = gallium_drivers.length() != 0 and gallium_drivers != ['']
+with_gallium = gallium_drivers.length() != 0
 
 if with_gallium and system_has_kms_drm
   _glx = get_option('glx')
@@ -261,7 +261,7 @@ endif
 with_intel_vk = _vulkan_drivers.contains('intel')
 with_amd_vk = _vulkan_drivers.contains('amd')
 with_freedreno_vk = _vulkan_drivers.contains('freedreno')
-with_any_vk = _vulkan_drivers.length() != 0 and _vulkan_drivers != ['']
+with_any_vk = _vulkan_drivers.length() != 0
 
 if with_dri_swrast and (with_gallium_softpipe or with_gallium_swr)
   error('Only one swrast provider can be built')
@@ -314,13 +314,7 @@ with_platform_haiku = _platforms.contains('haiku')
 with_platform_surfaceless = _platforms.contains('surfaceless')
 with_platform_windows = _platforms.contains('windows')
 
-with_platforms = false
-if _platforms.length() != 0 and _platforms != ['']
-  # sanity check that list contains no empty strings
-  if _platforms.contains('')
-    error('Invalid argument list given to -Dplatforms, please fix.')
-  endif
-  with_platforms = true
+if _platforms.length() != 0
   egl_native_platform = _platforms[0]
 endif
 
@@ -399,14 +393,14 @@ endif
 if _egl == 'auto'
   with_egl = (
     not ['darwin', 'windows'].contains(host_machine.system()) and
-    with_dri and with_shared_glapi and with_platforms
+    with_dri and with_shared_glapi and _platforms.length() != 0
   )
 elif _egl == 'enabled'
   if not with_dri
     error('EGL requires dri')
   elif not with_shared_glapi
     error('EGL requires shared-glapi')
-  elif not with_platforms
+  elif _platforms.length() == 0
     error('No platforms specified, consider -Dplatforms=drm,x11,surfaceless at least')
   elif not ['disabled', 'dri'].contains(with_glx)
     error('EGL requires dri, but a GLX is being built without dri')
@@ -1898,7 +1892,7 @@ if with_egl
   lines += 'EGL drivers:     ' + ' '.join(egl_drivers)
 endif
 lines += 'GBM:             ' + (with_gbm ? 'yes' : 'no')
-if with_platforms
+if _platforms.length() != 0
   lines += 'EGL/Vulkan/VL platforms:   ' + ' '.join(_platforms)
 endif
 
diff --git a/meson_options.txt b/meson_options.txt
index 464b99286ee..913dd497449 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -23,7 +23,7 @@ option(
   type : 'array',
   value : ['auto'],
   choices : [
-    '', 'auto', 'x11', 'wayland', 'drm', 'surfaceless', 'haiku', 'android',
+    'auto', 'x11', 'wayland', 'drm', 'surfaceless', 'haiku', 'android',
     'windows',
   ],
   description : 'window systems to support. If this is set to `auto`, all platforms applicable will be enabled.'
@@ -39,7 +39,7 @@ option(
   'dri-drivers',
   type : 'array',
   value : ['auto'],
-  choices : ['', 'auto', 'i915', 'i965', 'r100', 'r200', 'nouveau', 'swrast'],
+  choices : ['auto', 'i915', 'i965', 'r100', 'r200', 'nouveau', 'swrast'],
   description : 'List of dri drivers to build. If this is set to auto all drivers applicable to the target OS/architecture will be built'
 )
 option(
@@ -59,7 +59,7 @@ option(
   type : 'array',
   value : ['auto'],
   choices : [
-    '', 'auto', 'kmsro', 'radeonsi', 'r300', 'r600', 'nouveau', 'freedreno',
+    'auto', 'kmsro', 'radeonsi', 'r300', 'r600', 'nouveau', 'freedreno',
     'swrast', 'v3d', 'vc4', 'etnaviv', 'tegra', 'i915', 'svga', 'virgl',
     'swr', 'panfrost', 'iris', 'lima', 'zink'
   ],
@@ -159,7 +159,7 @@ option(
   'vulkan-drivers',
   type : 'array',
   value : ['auto'],
-  choices : ['', 'auto', 'amd', 'freedreno', 'intel'],
+  choices : ['auto', 'amd', 'freedreno', 'intel'],
   description : 'List of vulkan drivers to build. If this is set to auto all drivers applicable to the target OS/architecture will be built'
 )
 option(