Disallow empty types in the component model

crates/wasmparser/src/validator/component.rs

@@ -2482,6 +2482,10 @@ impl ComponentState {
         let mut type_size = 1;
         let mut field_map = IndexMap::with_capacity(fields.len());
 
+        if fields.is_empty() {
+            bail!(offset, "record type must have at least one field");
+        }
+
         for (name, ty) in fields {
             let name = to_kebab_str(name, "record field", offset)?;
             let ty = self.create_component_val_type(*ty, types, offset)?;
@@ -2515,10 +2519,7 @@ impl ComponentState {
         let mut case_map: IndexMap<KebabString, VariantCase> = IndexMap::with_capacity(cases.len());
 
         if cases.is_empty() {
-            return Err(BinaryReaderError::new(
-                "variant type must have at least one case",
-                offset,
-            ));
+            bail!(offset, "variant type must have at least one case");
         }
 
         if cases.len() > u32::MAX as usize {
@@ -2584,6 +2585,9 @@ impl ComponentState {
         offset: usize,
     ) -> Result<ComponentDefinedType> {
         let mut type_size = 1;
+        if tys.is_empty() {
+            bail!(offset, "tuple type must have at least one type");
+        }
         let types = tys
             .iter()
             .map(|ty| {
@@ -2599,6 +2603,10 @@ impl ComponentState {
     fn create_flags_type(&self, names: &[&str], offset: usize) -> Result<ComponentDefinedType> {
         let mut names_set = IndexSet::with_capacity(names.len());
 
+        if names.is_empty() {
+            bail!(offset, "flags must have at least one entry");
+        }
+
         for name in names {
             let name = to_kebab_str(name, "flag", offset)?;
             if !names_set.insert(name.to_owned()) {
@@ -2621,6 +2629,10 @@ impl ComponentState {
             ));
         }
 
+        if cases.is_empty() {
+            bail!(offset, "enum type must have at least one variant");
+        }
+
         let mut tags = IndexSet::with_capacity(cases.len());
 
         for tag in cases {
@@ -2644,6 +2656,9 @@ impl ComponentState {
         offset: usize,
     ) -> Result<ComponentDefinedType> {
         let mut type_size = 1;
+        if tys.is_empty() {
+            bail!(offset, "union type must have at least one case");
+        }
         let types = tys
             .iter()
             .map(|ty| {

crates/wit-component/tests/components/export-interface-using-import/component.wat

@@ -1,7 +1,7 @@
 (component
   (type (;0;)
     (instance
-      (type (;0;) (record))
+      (type (;0;) (record (field "f" u32)))
       (export (;1;) "f" (type (eq 0)))
       (type (;2;) (record (field "f" 1)))
       (export (;3;) "r" (type (eq 2)))
@@ -18,7 +18,7 @@
   (alias export 0 "f" (type (;1;)))
   (alias export 0 "r" (type (;2;)))
   (component (;0;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u32)))
     (import "import-type-f" (type (;1;) (eq 0)))
     (type (;2;) (record (field "f" 1)))
     (import "import-type-r" (type (;3;) (eq 2)))

crates/wit-component/tests/components/export-interface-using-import/module.wit

@@ -1,7 +1,9 @@
 package foo:foo
 
 interface foo {
-  record f {}
+  record f {
+    f: u32,
+  }
 
   record r {
     f: f,

crates/wit-component/tests/components/export-name-shuffling/component.wat

@@ -1,7 +1,7 @@
 (component
   (core module (;0;)
-    (type (;0;) (func))
-    (func (;0;) (type 0))
+    (type (;0;) (func (param i32)))
+    (func (;0;) (type 0) (param i32))
     (export "name#a" (func 0))
     (@producers
       (processed-by "wit-component" "$CARGO_PKG_VERSION")
@@ -10,7 +10,7 @@
   )
   (core instance (;0;) (instantiate 0))
   (component (;0;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u32)))
     (export (;1;) "foo" (type 0))
   )
   (instance (;0;) (instantiate 0))
@@ -20,7 +20,7 @@
   (alias core export 0 "name#a" (core func (;0;)))
   (func (;0;) (type 1) (canon lift (core func 0)))
   (component (;1;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u32)))
     (import "import-type-foo" (type (;1;) (eq 0)))
     (import "import-type-foo0" (type (;2;) (eq 1)))
     (type (;3;) (func (param "f" 2)))

crates/wit-component/tests/components/export-name-shuffling/module.wat

@@ -1,3 +1,3 @@
 (module
-  (func (export "name#a"))
+  (func (export "name#a") (param i32))
 )

crates/wit-component/tests/components/export-name-shuffling/module.wit

@@ -1,7 +1,9 @@
 package foo:foo
 
 interface name {
-  record foo {}
+  record foo {
+    f: u32,
+  }
 }
 
 world module {

crates/wit-component/tests/components/export-type-name-conflict/component.wat

@@ -1,14 +1,16 @@
 (component
   (type (;0;)
     (instance
-      (type (;0;) (record))
+      (type (;0;) (record (field "f" u8)))
       (export (;1;) "foo" (type (eq 0)))
     )
   )
   (import (interface "foo:foo/foo") (instance (;0;) (type 0)))
   (core module (;0;)
-    (type (;0;) (func))
-    (func (;0;) (type 0))
+    (type (;0;) (func (result i32)))
+    (func (;0;) (type 0) (result i32)
+      unreachable
+    )
     (export "bar#foo" (func 0))
     (@producers
       (processed-by "wit-component" "$CARGO_PKG_VERSION")
@@ -22,7 +24,7 @@
   (func (;0;) (type 2) (canon lift (core func 0)))
   (alias export 0 "foo" (type (;3;)))
   (component (;0;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u8)))
     (import "import-type-foo" (type (;1;) (eq 0)))
     (import "import-type-bar" (type (;2;) (eq 1)))
     (type (;3;) (func (result 2)))

crates/wit-component/tests/components/export-type-name-conflict/module.wat

@@ -1,3 +1,5 @@
 (module
-  (func (export "bar#foo"))
+  (func (export "bar#foo") (result i32)
+    unreachable
+  )
 )

crates/wit-component/tests/components/export-type-name-conflict/module.wit

@@ -1,7 +1,9 @@
 package foo:foo
 
 interface foo {
-  record foo {}
+  record foo {
+    f: u8,
+  }
 }
 
 world module {

crates/wit-component/tests/components/imports/module.wit

@@ -26,6 +26,8 @@ world module {
 
     // doesn't show up in the wit output despite being exported here since it's
     // not actually used by anything
-    record unused-record {}
+    record unused-record {
+      f: u8,
+    }
   }
 }

crates/wit-component/tests/components/many-same-names/component.wat

@@ -1,7 +1,7 @@
 (component
   (type (;0;)
     (instance
-      (type (;0;) (record))
+      (type (;0;) (record (field "f" u8)))
       (export (;1;) "r1" (type (eq 0)))
       (type (;2;) (record (field "x" 1)))
       (export (;3;) "r2" (type (eq 2)))
@@ -19,7 +19,7 @@
   )
   (core instance (;0;) (instantiate 0))
   (component (;0;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u8)))
     (export (;1;) "r1" (type 0))
     (type (;2;) (record (field "x" 1)))
     (export (;3;) "r2" (type 2))
@@ -32,7 +32,7 @@
   (alias export 2 "r1" (type (;2;)))
   (alias export 2 "r2" (type (;3;)))
   (component (;1;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u8)))
     (import "import-type-r1" (type (;1;) (eq 0)))
     (type (;2;) (record (field "x" 1)))
     (import "import-type-r2" (type (;3;) (eq 2)))

crates/wit-component/tests/components/many-same-names/module.wit

@@ -1,7 +1,9 @@
 package foo:foo
 
 interface name {
-  record r1 {}
+  record r1 {
+    f: u8,
+  }
 
   record r2 {
     x: r1

crates/wit-component/tests/components/rename-interface/component.wat

@@ -1,7 +1,7 @@
 (component
   (type (;0;)
     (instance
-      (type (;0;) (record))
+      (type (;0;) (record (field "f" u8)))
       (export (;1;) "bar" (type (eq 0)))
     )
   )
@@ -17,7 +17,7 @@
   )
   (import "other-name" (instance (;1;) (type 2)))
   (core module (;0;)
-    (type (;0;) (func))
+    (type (;0;) (func (result i32)))
     (import "other-name" "a" (func (;0;) (type 0)))
     (@producers
       (processed-by "wit-component" "$CARGO_PKG_VERSION")

crates/wit-component/tests/components/rename-interface/module.wat

@@ -1,3 +1,3 @@
 (module
-  (import "other-name" "a" (func))
+  (import "other-name" "a" (func (result i32)))
 )

crates/wit-component/tests/components/rename-interface/module.wit

@@ -1,7 +1,9 @@
 package foo:foo
 
 interface foo {
-  record bar {}
+  record bar {
+    f: u8,
+  }
 
   a: func() -> bar
 }

crates/wit-component/tests/components/tricky-order/component.wat

@@ -1,7 +1,7 @@
 (component
   (type (;0;)
     (instance
-      (type (;0;) (record))
+      (type (;0;) (record (field "f" u8)))
       (export (;1;) "name" (type (eq 0)))
     )
   )
@@ -24,7 +24,7 @@
   (alias export 0 "name" (type (;3;)))
   (alias export 1 "name" (type (;4;)))
   (component (;0;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u8)))
     (import "import-type-name" (type (;1;) (eq 0)))
     (import "import-type-name0" (type (;2;) (eq 1)))
     (export (;3;) "name" (type 1))

crates/wit-component/tests/components/tricky-order/module.wit

@@ -1,7 +1,9 @@
 package foo:foo
 
 interface name1 {
-  record name {}
+  record name {
+    f: u8,
+  }
 }
 
 interface name2 {

crates/wit-component/tests/components/worlds-with-type-renamings/component.wat

@@ -1,7 +1,7 @@
 (component
   (type (;0;)
     (instance
-      (type (;0;) (record))
+      (type (;0;) (record (field "f" u8)))
       (export (;1;) "some-type" (type (eq 0)))
       (type (;2;) (func (result 1)))
       (export (;0;) "the-func" (func (type 2)))
@@ -13,9 +13,9 @@
   (core module (;0;)
     (type (;0;) (func (param i32 i64 i32)))
     (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
-    (type (;2;) (func))
+    (type (;2;) (func (result i32)))
     (import "foo:foo/i" "the-func" (func (;0;) (type 2)))
-    (func (;1;) (type 2)
+    (func (;1;) (type 2) (result i32)
       unreachable
     )
     (func (;2;) (type 1) (param i32 i32 i32 i32) (result i32)
@@ -41,16 +41,16 @@
   )
   (alias core export 1 "memory" (core memory (;0;)))
   (alias core export 1 "cabi_realloc" (core func (;1;)))
-  (type (;3;) (record))
+  (type (;3;) (record (field "f" u8)))
   (type (;4;) (func (result 3)))
   (alias core export 1 "foo:foo/i#the-func" (core func (;2;)))
   (func (;1;) (type 4) (canon lift (core func 2)))
   (component (;0;)
-    (type (;0;) (record))
+    (type (;0;) (record (field "f" u8)))
     (import "import-type-some-type" (type (;1;) (eq 0)))
     (type (;2;) (func (result 1)))
     (import "import-func-the-func" (func (;0;) (type 2)))
-    (type (;3;) (record))
+    (type (;3;) (record (field "f" u8)))
     (export (;4;) "some-type" (type 3))
     (type (;5;) (func (result 4)))
     (export (;1;) "the-func" (func 0) (func (type 5)))

crates/wit-component/tests/components/worlds-with-type-renamings/module.wat

@@ -1,8 +1,8 @@
 (module
   (type (;0;) (func (param i32 i64 i32)))
   (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
-  (import "foo:foo/i" "the-func" (func (;0;)))
-  (func (export "foo:foo/i#the-func")
+  (import "foo:foo/i" "the-func" (func (result i32)))
+  (func (export "foo:foo/i#the-func") (result i32)
     unreachable
   )
   (func (;2;) (export "cabi_realloc") (param i32 i32 i32 i32) (result i32)

crates/wit-component/tests/components/worlds-with-type-renamings/module.wit

@@ -2,6 +2,7 @@ package foo:foo
 
 interface i {
   record some-type {
+    f: u8,
   }
 
   the-func: func() -> some-type

crates/wit-component/tests/interfaces/multi-doc.wat

@@ -3,7 +3,7 @@
     (component
       (type (;0;)
         (instance
-          (type (;0;) (record))
+          (type (;0;) (record (field "f" u8)))
           (export (;1;) "the-type" (type (eq 0)))
         )
       )

crates/wit-component/tests/interfaces/multi-doc/b.wit

@@ -3,5 +3,7 @@ interface a2 {
 }
 
 interface b {
-  record the-type {}
+  record the-type {
+    f: u8,
+  }
 }

crates/wit-component/tests/interfaces/multi-doc/foo.wit.print

@@ -2,6 +2,7 @@ package foo:foo
 
 interface b {
   record the-type {
+    f: u8,
   }
 }
 

crates/wit-component/tests/interfaces/pkg-use-chain2.wat

@@ -3,7 +3,7 @@
     (component
       (type (;0;)
         (instance
-          (type (;0;) (record))
+          (type (;0;) (record (field "f" u8)))
           (export (;1;) "name" (type (eq 0)))
         )
       )

crates/wit-component/tests/interfaces/pkg-use-chain2/bar.wit

@@ -7,5 +7,7 @@ interface bar {
 }
 
 interface other {
-  record name {}
+  record name {
+    f: u8,
+  }
 }