Forum: Ruby-core [ruby-trunk - Bug #7647][Open] Ruby 1.9.3 doesn't build on m68k due to alignment of structs

Issue #7647 has been reported by alanh (Alan Hourihane).

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Bug #7647: Ruby 1.9.3 doesn't build on m68k due to alignment of structs
https://bugs.ruby-lang.org/issues/7647

Author: alanh (Alan Hourihane)
Status: Open
Priority: Normal
Assignee:
Category:
Target version:
ruby -v: 0


I'd built Ruby 1.8 without any problems, but 1.9.3 shows up an issue 
with Ruby due to alignment checking.

When executing Init_var_tables(), we execute....

CONST_ID(autoload, "__autoload__");

We end up, in rb_intern3() and use the RString struct to pass into 
rb_enc_associate() which checks alignment with SPECIAL_CONST_P(x) via 
IMMEDIATE(x) and uses the RUBY_IMMEDIATE_MASK which is defined as 0x03.

This can fail on m68k as structs can be aligned on 16bit boundaries. I 
had to change....

struct RString fake_str;

to

struct RString fake_str __attribute__ ((aligned (4)));

To get miniruby to build, but I'm not sure of other lurkers and whether 
this strict use of IMMEDIATE(x) is really valid.