Implement Union in terms of Variant

ip11 · Feb 11, 2021 · b07d794 · b07d794
1 parent 1e48303
commit b07d794
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diff --git a/phases/ephemeral/docs.md b/phases/ephemeral/docs.md
@@ -859,20 +859,18 @@ The state of the file descriptor.
 
 Offset: 8
 
-## <a href="#event_u" name="event_u"></a> `event_u`: Union
+## <a href="#event_u" name="event_u"></a> `event_u`: Variant
 The contents of an [`event`](#event).
 
 Size: 24
 
 Alignment: 8
 
-### Union Layout
+### Variant Layout
+- size: 24
+- align: 8
 - tag_size: 1
-- tag_align: 1
-- contents_offset: 8
-- contents_size: 16
-- contents_align: 8
-### Union variants
+### Variant cases
 - <a href="#event_u.fd_read" name="event_u.fd_read"></a> `fd_read`: [`event_fd_readwrite`](#event_fd_readwrite)
 
 - <a href="#event_u.fd_write" name="event_u.fd_write"></a> `fd_write`: [`event_fd_readwrite`](#event_fd_readwrite)
@@ -961,20 +959,18 @@ The file descriptor on which to wait for it to become ready for reading or writi
 
 Offset: 0
 
-## <a href="#subscription_u" name="subscription_u"></a> `subscription_u`: Union
+## <a href="#subscription_u" name="subscription_u"></a> `subscription_u`: Variant
 The contents of a [`subscription`](#subscription).
 
 Size: 40
 
 Alignment: 8
 
-### Union Layout
+### Variant Layout
+- size: 40
+- align: 8
 - tag_size: 1
-- tag_align: 1
-- contents_offset: 8
-- contents_size: 32
-- contents_align: 8
-### Union variants
+### Variant cases
 - <a href="#subscription_u.clock" name="subscription_u.clock"></a> `clock`: [`subscription_clock`](#subscription_clock)
 
 - <a href="#subscription_u.fd_read" name="subscription_u.fd_read"></a> `fd_read`: [`subscription_fd_readwrite`](#subscription_fd_readwrite)
@@ -1078,20 +1074,18 @@ The length of the directory name for use with `fd_prestat_dir_name`.
 
 Offset: 0
 
-## <a href="#prestat" name="prestat"></a> `prestat`: Union
+## <a href="#prestat" name="prestat"></a> `prestat`: Variant
 Information about a pre-opened capability.
 
 Size: 8
 
 Alignment: 4
 
-### Union Layout
+### Variant Layout
+- size: 8
+- align: 4
 - tag_size: 1
-- tag_align: 1
-- contents_offset: 4
-- contents_size: 4
-- contents_align: 4
-### Union variants
+### Variant cases
 - <a href="#prestat.dir" name="prestat.dir"></a> `dir`: [`prestat_dir`](#prestat_dir)
 When type is [`preopentype::dir`](#preopentype.dir):
 

diff --git a/phases/ephemeral/witx/typenames.witx b/phases/ephemeral/witx/typenames.witx
@@ -562,10 +562,10 @@
 
 ;;; The contents of an `event`.
 (typename $event_u
-  (union $eventtype
-    (field $fd_read $event_fd_readwrite)
-    (field $fd_write $event_fd_readwrite)
-    (empty $clock)
+  (variant (@witx tag $eventtype)
+    (case $fd_read $event_fd_readwrite)
+    (case $fd_write $event_fd_readwrite)
+    (case $clock)
   )
 )
 
@@ -620,10 +620,10 @@
 
 ;;; The contents of a `subscription`.
 (typename $subscription_u
-  (union $eventtype
-    (field $clock $subscription_clock)
-    (field $fd_read $subscription_fd_readwrite)
-    (field $fd_write $subscription_fd_readwrite)
+  (union (@witx tag $eventtype)
+    $subscription_clock
+    $subscription_fd_readwrite
+    $subscription_fd_readwrite
   )
 )
 
@@ -691,8 +691,8 @@
 
 ;;; Information about a pre-opened capability.
 (typename $prestat
-  (union $preopentype
+  (union (@witx tag $preopentype)
     ;;; When type is `preopentype::dir`:
-    (field $dir $prestat_dir)
+    $prestat_dir
   )
 )
diff --git a/phases/old/snapshot_0/docs.md b/phases/old/snapshot_0/docs.md
@@ -899,20 +899,18 @@ The file descriptor on which to wait for it to become ready for reading or writi
 
 Offset: 0
 
-## <a href="#subscription_u" name="subscription_u"></a> `subscription_u`: Union
+## <a href="#subscription_u" name="subscription_u"></a> `subscription_u`: Variant
 The contents of a [`subscription`](#subscription).
 
 Size: 48
 
 Alignment: 8
 
-### Union Layout
+### Variant Layout
+- size: 48
+- align: 8
 - tag_size: 1
-- tag_align: 1
-- contents_offset: 8
-- contents_size: 40
-- contents_align: 8
-### Union variants
+### Variant cases
 - <a href="#subscription_u.clock" name="subscription_u.clock"></a> `clock`: [`subscription_clock`](#subscription_clock)
 
 - <a href="#subscription_u.fd_read" name="subscription_u.fd_read"></a> `fd_read`: [`subscription_fd_readwrite`](#subscription_fd_readwrite)
@@ -1148,20 +1146,18 @@ The length of the directory name for use with [`fd_prestat_dir_name`](#fd_presta
 
 Offset: 0
 
-## <a href="#prestat" name="prestat"></a> `prestat`: Union
+## <a href="#prestat" name="prestat"></a> `prestat`: Variant
 Information about a pre-opened capability.
 
 Size: 8
 
 Alignment: 4
 
-### Union Layout
+### Variant Layout
+- size: 8
+- align: 4
 - tag_size: 1
-- tag_align: 1
-- contents_offset: 4
-- contents_size: 4
-- contents_align: 4
-### Union variants
+### Variant cases
 - <a href="#prestat.dir" name="prestat.dir"></a> `dir`: [`prestat_dir`](#prestat_dir)
 
 # Modules

diff --git a/phases/old/snapshot_0/witx/typenames.witx b/phases/old/snapshot_0/witx/typenames.witx
@@ -570,10 +570,10 @@
 
 ;;; The contents of a `subscription`.
 (typename $subscription_u
-  (union $eventtype
-    (field $clock $subscription_clock)
-    (field $fd_read $subscription_fd_readwrite)
-    (field $fd_write $subscription_fd_readwrite)
+  (union (@witx tag $eventtype)
+    $subscription_clock
+    $subscription_fd_readwrite
+    $subscription_fd_readwrite
   )
 )
 
@@ -740,7 +740,7 @@
 
 ;;; Information about a pre-opened capability.
 (typename $prestat
-  (union $preopentype
-    (field $dir $prestat_dir)
+  (union (@witx tag $preopentype)
+    $prestat_dir
   )
 )
diff --git a/phases/snapshot/docs.md b/phases/snapshot/docs.md
@@ -896,20 +896,18 @@ The file descriptor on which to wait for it to become ready for reading or writi
 
 Offset: 0
 
-## <a href="#subscription_u" name="subscription_u"></a> `subscription_u`: Union
+## <a href="#subscription_u" name="subscription_u"></a> `subscription_u`: Variant
 The contents of a [`subscription`](#subscription).
 
 Size: 40
 
 Alignment: 8
 
-### Union Layout
+### Variant Layout
+- size: 40
+- align: 8
 - tag_size: 1
-- tag_align: 1
-- contents_offset: 8
-- contents_size: 32
-- contents_align: 8
-### Union variants
+### Variant cases
 - <a href="#subscription_u.clock" name="subscription_u.clock"></a> `clock`: [`subscription_clock`](#subscription_clock)
 
 - <a href="#subscription_u.fd_read" name="subscription_u.fd_read"></a> `fd_read`: [`subscription_fd_readwrite`](#subscription_fd_readwrite)
@@ -1145,20 +1143,18 @@ The length of the directory name for use with [`fd_prestat_dir_name`](#fd_presta
 
 Offset: 0
 
-## <a href="#prestat" name="prestat"></a> `prestat`: Union
+## <a href="#prestat" name="prestat"></a> `prestat`: Variant
 Information about a pre-opened capability.
 
 Size: 8
 
 Alignment: 4
 
-### Union Layout
+### Variant Layout
+- size: 8
+- align: 4
 - tag_size: 1
-- tag_align: 1
-- contents_offset: 4
-- contents_size: 4
-- contents_align: 4
-### Union variants
+### Variant cases
 - <a href="#prestat.dir" name="prestat.dir"></a> `dir`: [`prestat_dir`](#prestat_dir)
 
 # Modules

diff --git a/phases/snapshot/witx/typenames.witx b/phases/snapshot/witx/typenames.witx
@@ -570,10 +570,11 @@
 
 ;;; The contents of a `subscription`.
 (typename $subscription_u
-  (union $eventtype
-    (field $clock $subscription_clock)
-    (field $fd_read  $subscription_fd_readwrite)
-    (field $fd_write $subscription_fd_readwrite)
+  (union
+    (@witx tag $eventtype)
+    $subscription_clock
+    $subscription_fd_readwrite
+    $subscription_fd_readwrite
   )
 )
 
@@ -740,8 +741,8 @@
 
 ;;; Information about a pre-opened capability.
 (typename $prestat
-  (union $preopentype
-    (field $dir $prestat_dir)
+  (union (@witx tag $preopentype)
+    $prestat_dir
   )
 )
 
diff --git a/tools/witx/src/ast.rs b/tools/witx/src/ast.rs
@@ -187,7 +187,6 @@ impl NamedType {
 pub enum Type {
     Record(RecordDatatype),
     Variant(Variant),
-    Union(UnionDatatype),
     Handle(HandleDatatype),
     List(TypeRef),
     Pointer(TypeRef),
@@ -201,7 +200,6 @@ impl Type {
         match self {
             Record(_) => "record",
             Variant(_) => "variant",
-            Union(_) => "union",
             Handle(_) => "handle",
             List(_) => "list",
             Pointer(_) => "pointer",
@@ -272,19 +270,6 @@ pub struct Case {
     pub docs: String,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct UnionDatatype {
-    pub tag: Rc<NamedType>,
-    pub variants: Vec<UnionVariant>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct UnionVariant {
-    pub name: Id,
-    pub tref: Option<TypeRef>,
-    pub docs: String,
-}
-
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct HandleDatatype {}
 

diff --git a/tools/witx/src/coretypes.rs b/tools/witx/src/coretypes.rs
@@ -50,7 +50,7 @@ impl Type {
             },
             Type::List { .. } => TypePassedBy::PointerLengthPair,
             Type::Pointer { .. } | Type::ConstPointer { .. } => TypePassedBy::Value(AtomType::I32),
-            Type::Record { .. } | Type::Union { .. } => TypePassedBy::Pointer,
+            Type::Record { .. } => TypePassedBy::Pointer,
             Type::Variant(v) => {
                 if v.cases.iter().all(|c| c.tref.is_none()) {
                     TypePassedBy::Value(v.tag_repr.into())