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 _builtinunreachable():

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

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

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

[Yui NARUSE]

• Status changed from Open to Closed

r34784 uses _builtinunreachable().

[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]

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

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 (rbenccodepoint_len): Use UNREACHABLE to avoid "control reaches end of non-void function" warnings. [ruby-trunk - Bug #6066]
• re.c (nametobackref_number): ditto.
• object.c (rb_Float): ditto.
• io.c (io_readpartial): ditto.
• io.c (ioreadnonblock): ditto.
• pack.c (rbuvto_utf8): ditto.
• proc.c (rbmethodentry_arity): ditto.
• vmmethod.c (rbf_notimplement): ditto.
• struct.c (rbstructaset_id): ditto.
• class.c (rbscanargs): ditto.
• process.c (rlimitresourcetype): ditto.
• process.c (rlimitresourcevalue): ditto.
• process.c (puidswitch): ditto.
• process.c (pgidswitch): ditto.
• ext/digest/digest.c (rbdigestinstance_update): ditto.
• ext/digest/digest.c (rbdigestinstance_finish): ditto.
• ext/digest/digest.c (rbdigestinstance_reset): ditto.
• ext/digest/digest.c (rbdigestinstanceblocklength): ditto.
• ext/bigdecimal/bigdecimal.c (BigDecimalCmp): ditto.
• ext/dl/handle.c (rbdlhandleclose): ditto.
• ext/tk/tcltklib.c (pendingexceptioncheck0): ditto.
• ext/tk/tcltklib.c (pendingexceptioncheck1): ditto.
• ext/tk/tcltklib.c (ipcanceleval_core): ditto.
• ext/tk/tcltklib.c (libgetreltype_name): ditto.
• ext/tk/tcltklib.c (createdummyencodingfortk_core): ditto.
• ext/tk/tkutil/tkutil.c (tkhashkv): ditto.
• ext/openssl/osslssl.c (osslsslsessionreused): ditto.
• ext/openssl/osslpkeyec.c (ossleckeydsaverify_asn1): ditto.
• ext/openssl/osslpkeyec.c (osslecpointisat_infinit): ditto.
• ext/openssl/osslpkeyec.c (osslecpointison_curve): ditto.
• ext/fiddle/conversions.c (generictovalue): ditto.
• ext/socket/raddrinfo.c (rsockiosocket_addrinfo): ditto.
• ext/socket/socket.c (socksgetnameinfo): ditto.
• ext/ripper/eventids2.c (ripper_token2eventid): ditto.
• cont.c (return_fiber): ditto.
• dmydln.c (dln_load): ditto.
• vminsnhelper.c (vmsearchnormalsuperclass): 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
• Status changed from Closed to Assigned
• Target version set to 2.0.0

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