Woverlength-strings warnings in clang 3.4

[evoskuil]

Environment:

clang version 3.4 (tags/RELEASE_34/final)
Target: x86_64-unknown-linux-gnu

Warnings:

  CC     src/libsecp256k1_la-secp256k1.lo
In file included from src/secp256k1.c:13:
In file included from ./src/field_impl.h:19:
In file included from ./src/field_5x52_impl.h:20:
./src/field_5x52_asm_impl.h:29:5: warning: string literal of length 3425 exceeds
      maximum length 509 that C90 compilers are required to support
      [-Woverlength-strings]
    "movq 0(%%rsi),%%r10\n"
    ^~~~~~~~~~~~~~~~~~~~~~~
./src/field_5x52_asm_impl.h:299:5: warning: string literal of length 2541
      exceeds maximum length 509 that C90 compilers are required to support
      [-Woverlength-strings]
    "movq 0(%%rsi),%%r10\n"
    ^~~~~~~~~~~~~~~~~~~~~~~
In file included from src/secp256k1.c:14:
In file included from ./src/scalar_impl.h:20:
./src/scalar_4x64_impl.h:262:5: warning: string literal of length 1191 exceeds
      maximum length 509 that C90 compilers are required to support
      [-Woverlength-strings]
    "movq 32(%%rsi), %%r11\n"
    ^~~~~~~~~~~~~~~~~~~~~~~~~
./src/scalar_4x64_impl.h:368:5: warning: string literal of length 821 exceeds
      maximum length 509 that C90 compilers are required to support
      [-Woverlength-strings]
    "movq %q9, %%r11\n"
    ^~~~~~~~~~~~~~~~~~~
./src/scalar_4x64_impl.h:567:5: warning: string literal of length 1643 exceeds
      maximum length 509 that C90 compilers are required to support
      [-Woverlength-strings]
    "movq 0(%%rdi), %%r15\n"
    ^~~~~~~~~~~~~~~~~~~~~~~~
./src/scalar_4x64_impl.h:733:5: warning: string literal of length 1383 exceeds
      maximum length 509 that C90 compilers are required to support
      [-Woverlength-strings]
    "movq 0(%%rdi), %%r11\n"
    ^~~~~~~~~~~~~~~~~~~~~~~~
6 warnings generated.
  CCLD   libsecp256k1.la

[gmaxwell]

Does adding _ _ extension _ _ in front of _ _ asm _ _ (two underscores before and after, no spaces) shut it up? (really asm itself is an extension, so I think it shouldn't be warning there, but lets see if that makes it happy.)

[evoskuil]

I don't think it likes that:

./src/field_5x52_asm_impl.h:298:15: error: expected expression
__extension__ __asm__ __volatile__(
              ^
./src/field_5x52_asm_impl.h:287:63: warning: unused parameter 'r'
      [-Wunused-parameter]
...

[sipa]

I believe it's a known problem. Older gcc versions also complain about this. I guess we can just disable -Woverlength-strings for now?

[evoskuil]

Seems fine to me.