Module Wax_wasm.Legacy_ehSource

module_ d m rewrites each legacy try/catch/catch_all instruction of m into a try_table wrapped in a ladder of blocks, one per handler:

block $t (type bt)              ;; the join, carrying the try's label
  block (param p) (result t_n)  ;; one block per handler, the last outermost
    ...
      block (param p) (result t_1)
        try_table (type bt) (catch tag_1 0) ... (catch_all n-1)
          body
        end
        br $t
      end
      handler_1
      br $t
    ...
  end
  handler_n                     ;; the last handler falls into the join
end

Each handler receives its tag's payload exactly as the legacy catch does, and a branch to the try's label, from the body or a handler, now targets the join, exiting the whole construct with its result. This is the shape Wax_lang.Ast_utils.lower_trycatch produces, so the decompiler recovers a structured try from it. Numeric branch depths are adjusted for the blocks introduced, so the rewrite also applies to a module decoded from a binary. The legacy rethrow and delegate are not supported by Wax, so every legacy try has an equivalent.

The input need not have been validated: a tag or type that resolves to nothing is reported to d. A tag or type name declared in several branches of a conditional annotation is resolved when all its declarations agree on the types the rewrite needs, and reported otherwise.