Bug #6066: Fix "control may reach end of non-void function" warnings for clang

[Eric Hodel]

=begin
clang 3.1 is more picky about "control may reach end of non-void function"

The attached patches contain add (({return Qnil; /* not reached */})) or the equivalent where the warnings occurred.
=end

[Eric Hodel]

Patches were not added in-order.

Note that return.combined.patch contains all the other patches grouped together

[Nobuyoshi Nakada]

clang 3.1 is more picky about "control may reach end of non-void function"

or doesn't deal with noreturn attribute properly?

Anyway, (ID)NULL seems odd.

[Eric Hodel]

=begin
Yes, (ID)NULL seems odd to me too.

clang supports __builtin_unreachable():

http://clang.llvm.org/docs/LanguageExtensions.html#__builtin_unreachable

It looks like replacing (({return Qnil; /* NOT REACHED */})) lines with __builtin_unreachable() may improve optimizations with clang.

Adding configure support to detect _builltin_unreachable() looks like it is beyond my knowledge based on the _builtin_setjmp() detection, can you help me?
=end

[Yui NARUSE]

• Status changed from Open to Closed

r34784 uses __builtin_unreachable().

[Nobuyoshi Nakada]

• Status changed from Closed to Open

No, the commit just checks the function, and defines UNREACHABLE macro.

[Eric Hodel]

Thank you, I will post an updated patch using UNREACHABLE

[Eric Hodel]

• File return.UNREACHABLE.patch added

This patch updates all -Wreturn-type warning locations to use the UNREACHABLE macro.

[Eric Hodel]

• File return.not_reached.convert.patch added

=begin
This patch updates existing (({return Qnil; /* not reached */})) with (({UNREACHABLE;}))

I did not change (({trace_en()})) in variable.c as it seems to return, I think the (({/* not reached */})) should be removed, but can you check it?
=end

[Koichi Sasada]

• Assignee set to Nobuyoshi Nakada

[Shyouhei Urabe]

• Status changed from Open to Assigned

[Eric Hodel]

Nobu, may I commit this?

[Nobuyoshi Nakada]

• Assignee changed from Nobuyoshi Nakada to Eric Hodel

Feel free.

[Eric Hodel]

• % Done changed from 0 to 100
• Status changed from Assigned to Closed

This issue was solved with changeset r35321.
Eric, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• encoding.c (rb_enc_codepoint_len): Use UNREACHABLE to avoid "control reaches end of non-void function" warnings. [ruby-trunk - Bug #6066]
• re.c (name_to_backref_number): ditto.
• object.c (rb_Float): ditto.
• io.c (io_readpartial): ditto.
• io.c (io_read_nonblock): ditto.
• pack.c (rb_uv_to_utf8): ditto.
• proc.c (rb_method_entry_arity): ditto.
• vm_method.c (rb_f_notimplement): ditto.
• struct.c (rb_struct_aset_id): ditto.
• class.c (rb_scan_args): ditto.
• process.c (rlimit_resource_type): ditto.
• process.c (rlimit_resource_value): ditto.
• process.c (p_uid_switch): ditto.
• process.c (p_gid_switch): ditto.
• ext/digest/digest.c (rb_digest_instance_update): ditto.
• ext/digest/digest.c (rb_digest_instance_finish): ditto.
• ext/digest/digest.c (rb_digest_instance_reset): ditto.
• ext/digest/digest.c (rb_digest_instance_block_length): ditto.
• ext/bigdecimal/bigdecimal.c (BigDecimalCmp): ditto.
• ext/dl/handle.c (rb_dlhandle_close): ditto.
• ext/tk/tcltklib.c (pending_exception_check0): ditto.
• ext/tk/tcltklib.c (pending_exception_check1): ditto.
• ext/tk/tcltklib.c (ip_cancel_eval_core): ditto.
• ext/tk/tcltklib.c (lib_get_reltype_name): ditto.
• ext/tk/tcltklib.c (create_dummy_encoding_for_tk_core): ditto.
• ext/tk/tkutil/tkutil.c (tk_hash_kv): ditto.
• ext/openssl/ossl_ssl.c (ossl_ssl_session_reused): ditto.
• ext/openssl/ossl_pkey_ec.c (ossl_ec_key_dsa_verify_asn1): ditto.
• ext/openssl/ossl_pkey_ec.c (ossl_ec_point_is_at_infinit): ditto.
• ext/openssl/ossl_pkey_ec.c (ossl_ec_point_is_on_curve): ditto.
• ext/fiddle/conversions.c (generic_to_value): ditto.
• ext/socket/raddrinfo.c (rsock_io_socket_addrinfo): ditto.
• ext/socket/socket.c (sock_s_getnameinfo): ditto.
• ext/ripper/eventids2.c (ripper_token2eventid): ditto.
• cont.c (return_fiber): ditto.
• dmydln.c (dln_load): ditto.
• vm_insnhelper.c (vm_search_normal_superclass): ditto.
• bignum.c (big_fdiv): ditto.
• marshal.c (r_symlink): ditto.
• marshal.c (r_symbol): ditto.

[Eric Hodel]

r35322 is also part of this bug, but I forgot to mention it in my commit message.

[Nobuyoshi Nakada]

• Category set to misc
• Target version set to 2.0.0
• Status changed from Closed to Assigned

Thank you for the commit, and found r35322 let older compilers and non-gcc compilers warn unreachable code.
UNREACHABLE should not replace those `return's, but be appended, I think.

[Nobuyoshi Nakada]

• % Done changed from 100 to 50

[Nobuyoshi Nakada]

• Status changed from Assigned to Closed
• % Done changed from 50 to 100