Loosen kebab-case rules to allow non-first fragments to start with numbers

design/mvp/Explainer.md

@@ -2515,12 +2515,13 @@ plainname         ::= <label>
                     | '[constructor]' <label>
                     | '[method]' <label> '.' <label>
                     | '[static]' <label> '.' <label>
-label             ::= <fragment>
-                    | <label> '-' <fragment>
+label             ::= <first-fragment> ( '-' <fragment> )*
+first-fragment    ::= [a-z] <word>
+                    | [A-Z] <acronym>
 fragment          ::= <word>
                     | <acronym>
-word              ::= [a-z] [0-9a-z]*
-acronym           ::= [A-Z] [0-9A-Z]*
+word              ::= [0-9a-z]*
+acronym           ::= [0-9A-Z]*
 interfacename     ::= <namespace> <label> <projection> <interfaceversion>?
                     | <namespace>+ <label> <projection>+ <interfaceversion>? 🪺
 namespace         ::= <words> ':'
@@ -2675,6 +2676,16 @@ mapped to `isXML`, `IsXml`, `is_XML` or `is_xml`, depending on the target
 language/convention. The highly-restricted character set ensures that
 capitalization is trivial and does not require consulting Unicode tables.
 
+Based on the lexical definition of `label` above, the following are all valid
+labels:
+* `a`, `a-b-c`, `a1-2-3`, `A`, `A-B-C` and `A1-2-3` (but not `1-2-3`, since the
+  first fragment must start with a letter)
+* `a11-w0rds`, `A11-4CR0NYMS` and `m1x3d-4CR0NYMS`
+
+Technically, based on the definitions given, the `fragment` `2` (and `3`) in
+`a1-2-3` is ambiguously either a `word` or an `acronym`, but the distinction
+only relates to casing and numbers aren't cased.
+
 Components provide two options for naming exports, symmetric to the first two
 options for naming imports:
 * a **plain name** that leaves it up to the developer to "read the docs"

test/names/kebab.wast

@@ -0,0 +1,19 @@
+(component (component
+  (import "a" (func))
+  (import "a1" (func))
+  (import "a-1" (func))
+  (import "a-1-b-2-c-3" (func))
+  (import "B" (func))
+  (import "B1" (func))
+  (import "B-1" (func))
+  (import "B-1-C-2-D-3" (func))
+  (import "a11-B11-123-ABC-abc" (func))
+))
+(assert_invalid
+  (component
+    (import "1" (func)))
+  "is not in kebab case")
+(assert_invalid
+  (component
+    (import "1-a" (func)))
+  "is not in kebab case")

test/wasm-tools/naming.wast

@@ -22,11 +22,8 @@
   "instance 0 has no export named `Xml`"
 )
 
-(assert_invalid
-  (component
-    (type (flags "a-1-c"))
-  )
-  "flag name `a-1-c` is not in kebab case"
+(component definition
+  (type (flags "a-1-c"))
 )
 
 (assert_invalid