Incorrect width of insn_funct6 in I-type (shift variation) instruction format?

[DonaldKellett]

In the I-type (shift variation) instruction format (e.g. insns/insn_slli.v), the insn_funct6 field is defined as follows:

wire [6:0] insn_funct6 = rvfi_insn[31:26];

That is, while insn_funct6 is declared as a 7-bit field, it is assigned a 6-bit value. Also, in line 46 of the same file, we have insn_funct6 == 6'b 000000 as a subexpression which further suggests that insn_funct6 is treated as a 6-bit value for all intents and purposes.

I suppose this is unintentional, or am I missing something?