typedef struct { char a; int b; } *S7;

[phadej]

|-RecordDecl 0x27e80a70 <ex.h:1:9, col:33> col:9 struct definition
| |-FieldDecl 0x27e80b20 <col:18, col:23> col:23 a 'char'
| `-FieldDecl 0x27e80b88 <col:26, col:30> col:30 b 'int'
`-TypedefDecl 0x27e80ca0 <col:1, col:36> col:36 S7 'struct (unnamed struct at ex.h:1:9) *'
  `-PointerType 0x27e80c50 'struct (unnamed struct at ex.h:1:9) *'
    `-ElaboratedType 0x27e80be0 'struct (unnamed struct at ex.h:1:9)' sugar
      `-RecordType 0x27e80af0 'struct (unnamed at ex.h:1:9)'
        `-Record 0x27e80a70 ''

[phadej]

Here we need to come up with a name for the struct, as typedef is pointer to it. Rust bindgen generates

pub struct _bindgen_ty_1 {
    pub a: ::std::os::raw::c_char,
    pub b: ::std::os::raw::c_int,
}

pub type S7 = *mut _bindgen_ty_1;

[TravisCardwell]

Here is an initial design for a type constructor context:

data TypeConstrContext =
  ...
  | -- | Context for anonymous top-level structures/unions
    --
    -- Example: @typedef struct {...} *foo@
    AnonTopLevelTypeConstrContext {
      -- | Index (1-based) of anonymous top-level type constructors within the
      -- translation unit
      ctxAnonTopLevelTypeConstrIdx :: Word
    }

Perhaps the default could create names like HsBindgenType1, which is similar to the Rust behavior?

Another option would be to use the variable name, like how we use field names when an anonymous structure is for a named field.