ATM, javac's treatment of 'primitive' modifier employs a completely parallel scheme - unlike the other restricted identifiers (JLS 3.8) and needs to be harmonized.

See the methods

com.sun.tools.javac.parser.JavacParser#recastToken
com.sun.tools.javac.parser.JavacParser#restrictedTypeName
com.sun.tools.javac.parser.JavacParser#restrictedTypeNameStartingAtSource

ATM, none of yield, sealed, var, record etc have an Token kind
in com.sun.tools.javac.parser.Tokens.TokenKind while primitive
does

We may also not be emitting the pertinent diagnostics from this set:

IllegalRefToRestrictedType
RestrictedTypeNotAllowed
RestrictedTypeNotAllowedArray
RestrictedTypeNotAllowedCompound
RestrictedTypeNotAllowedHere
RestrictedTypeNotAllowedPreview

etc.

Both the spec and the implementation wrt to other restricted identifiers must be studied and the implementation must be aligned.