[Libguestfs] [virt-v2v wave 2 PATCH v2 01/16] lib/types: introduce "Standard_VGA" constructor for "guestcaps_video_type"

[Laszlo Ersek]

In order to replace QXL with Standard_VGA in small steps, bisectably,
first just introduce the Standard_VGA constructor.

Extend the string_of_video function at once ("stdvga"). The value returned
by this function is only used for debug logging (indirectly, via the
string_of_guestcaps function).

The virt-v2v build flags turn "non-exhaustive pattern matching" warnings
into errors. Match the new "Standard_VGA" constructor with a constant
false assertion wherever an expression of type "guestcaps_video_type" is
matched, in order to make this patch bisectable. These assertions will be
gradually replaced with actual logic in the rest of this patch set.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1961107
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---

Notes:
    v1:
    
    - drop the "convert/convert_linux.ml" and "convert/windows_virtio.ml"
      hunks, as those files don't match "guestcaps_video_type" expressions
      since commit b28cd1dcfeb4 ("Remove requested_guestcaps / rcaps",
      2021-11-08) [Rich]
    
    - remove the "string_of_requested_guestcaps" reference from the commit
      message, due to the same commit [Rich]
    
    - contextual conflict, due to commit f0afc4395248 ("Remove
      guestcaps_block_type Virtio_SCSI", 2021-11-08), auto-resolved in
      "lib/types.mli" and "lib/types.ml"

 lib/types.mli                        | 2 +-
 lib/types.ml                         | 3 ++-
 output/create_json.ml                | 1 +
 output/create_libvirt_xml.ml         | 1 +
 output/openstack_image_properties.ml | 1 +
 output/output.ml                     | 6 +++++-
 6 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/lib/types.mli b/lib/types.mli
index 3aab1ea7e4f2..3a2ba9fecf9a 100644
--- a/lib/types.mli
+++ b/lib/types.mli
@@ -284,7 +284,7 @@ type guestcaps = {
 
 and guestcaps_block_type = Virtio_blk | IDE
 and guestcaps_net_type = Virtio_net | E1000 | RTL8139
-and guestcaps_video_type = QXL | Cirrus
+and guestcaps_video_type = Standard_VGA | QXL | Cirrus
 and guestcaps_machine = I440FX | Q35 | Virt
 
 val string_of_guestcaps : guestcaps -> string
diff --git a/lib/types.ml b/lib/types.ml
index aeb7d71ae0a3..e7fc8b38787c 100644
--- a/lib/types.ml
+++ b/lib/types.ml
@@ -424,7 +424,7 @@ type guestcaps = {
 }
 and guestcaps_block_type = Virtio_blk | IDE
 and guestcaps_net_type = Virtio_net | E1000 | RTL8139
-and guestcaps_video_type = QXL | Cirrus
+and guestcaps_video_type = Standard_VGA | QXL | Cirrus
 and guestcaps_machine = I440FX | Q35 | Virt
 
 let string_of_block_type = function
@@ -435,6 +435,7 @@ let string_of_net_type = function
   | E1000 -> "e1000"
   | RTL8139 -> "rtl8139"
 let string_of_video = function
+  | Standard_VGA -> "stdvga"
   | QXL -> "qxl"
   | Cirrus -> "cirrus"
 let string_of_machine = function
diff --git a/output/create_json.ml b/output/create_json.ml
index 211cd5d648c0..3cadf6b43378 100644
--- a/output/create_json.ml
+++ b/output/create_json.ml
@@ -203,6 +203,7 @@ let create_json_metadata source inspect
       | RTL8139 -> "rtl8139" in
     let video =
       match guestcaps.gcaps_video with
+      | Standard_VGA -> assert false
       | QXL -> "qxl"
       | Cirrus -> "cirrus" in
     let machine =
diff --git a/output/create_libvirt_xml.ml b/output/create_libvirt_xml.ml
index 64f1b0888cd6..ec1cd455ef13 100644
--- a/output/create_libvirt_xml.ml
+++ b/output/create_libvirt_xml.ml
@@ -421,6 +421,7 @@ let create_libvirt_xml ?pool source inspect
   let video =
     let video_model =
       match guestcaps.gcaps_video with
+      | Standard_VGA -> assert false
       | QXL ->    e "model" [ "type", "qxl"; "ram", "65536" ] []
       | Cirrus -> e "model" [ "type", "cirrus"; "vram", "9216" ] [] in
     append_attr ("heads", "1") video_model;
diff --git a/output/openstack_image_properties.ml b/output/openstack_image_properties.ml
index bca0766e28c1..72f3e9d9261d 100644
--- a/output/openstack_image_properties.ml
+++ b/output/openstack_image_properties.ml
@@ -43,6 +43,7 @@ let create source inspect { target_buses; guestcaps; target_firmware } =
      | RTL8139 -> "rtl8139");
     "hw_video_model",
     (match guestcaps.gcaps_video with
+     | Standard_VGA -> assert false
      | QXL -> "qxl"
      | Cirrus -> "cirrus");
     "hw_machine_type",
diff --git a/output/output.ml b/output/output.ml
index 3b52f54b1cec..1101d2cfc73d 100644
--- a/output/output.ml
+++ b/output/output.ml
@@ -1539,7 +1539,11 @@ and qemu_finalize dir source inspect target_meta
                              "addr=127.0.0.1"]
       );
       arg "-vga"
-        (match guestcaps.gcaps_video with Cirrus -> "cirrus" | QXL -> "qxl")
+        (match guestcaps.gcaps_video with
+         | Standard_VGA -> assert false
+         | Cirrus -> "cirrus"
+         | QXL -> "qxl"
+        )
   );
 
   (* Add a sound card. *)
-- 
2.19.1.3.g30247aa5d201