the account formerly known as Luna

if C doesn't have reflection then explain this

https://gcc.godbolt.org/z/Gdo8vdYs4

Compiler Explorer - C (x86-64 clang 15.0.0)

/*\ } ()niam tni \*/ int main() { puts("Hello, World!"); /*\ ;("!dlroW ,olleH")stup { \*/ }

Nov 25, 2022 at 2:16pmWeb
Show threadMelissa Nov 25, 2022
@luna hold up
Show threadRigelian Art 🌈 🌊 🌐 πŸ‡ΊπŸ‡¦Nov 25, 2022
@codecat @luna
/ * Well … */
Show threadHayley (partly)Nov 25, 2022
@luna aaaaAAAAAA
Show threadb4ux1t3 #1️⃣Nov 25, 2022
@luna Bonus points for making it executable. A+.
Show threadlnNov 25, 2022
@luna oh that's beautiful
Show threadvoid friendNov 25, 2022
@luna Compiler Explorer allows you to be sneaky with the compile options: https://gcc.godbolt.org/z/5va1Gfa4E
Compiler Explorer - C (x86-64 clang 15.0.0)

/*\ } ()niam tni \*/ int main() { puts("Hello, World!"); /*\ ;("!dlroW ,olleH")stup { \*/ }

Show threadEmily SNov 25, 2022
@luna oooh a new auto formatter. Excellent 😈
Show threadkaitNov 25, 2022
@luna the first line is killing me this doesn't parse in my head 
Show threadNatalie A (Detwitter Arc)Nov 25, 2022
@kait @luna Yeah, how does the first line work? πŸ˜–
Show threadthe account formerly known as LunaNov 25, 2022
@larilille @kait tokens after the include directive get ignored (though the compiler will warn, and I suppressed the warning in the godbolt link)
Show threadNatalie A (Detwitter Arc)Nov 25, 2022
@luna @kait Because of course the preprocessor has an entirely separate syntax to the actual language... *sigh*
Show threadnone gender with left politics Nov 25, 2022
@luna @larilille @kait this was my guess but it's still ow
Show threadSimon Detheridge Nov 25, 2022
@luna I don't understand how the first line compiles. πŸ€”
Show threadthe account formerly known as LunaNov 25, 2022
@s there’s a hint on the godbolt page :)
Show threadSimon Detheridge Nov 25, 2022

@luna Oh... It looks like you can put any old garbage after a #include <foo>

TIL 

Show threadnotaNov 25, 2022
@luna This is amazing
Show threadmmu_manNov 25, 2022

@luna hmm the first line seems odd, sure it'd work regardless the preprocessor?

https://gcc.gnu.org/onlinedocs/cpp/Include-Syntax.html
"It is an error if there is anything (other than comments) on the line after the file name. "

Include Syntax (The C Preprocessor)

Include Syntax (The C Preprocessor)

Show threadGreg PriceNov 25, 2022

@mmu_man @luna It looks like the C standard also doesn't permit this trick. See section 6.10.2, pages 149-150: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf

Still, fun that with some compilers it can work!

Show threadfrankiezafeNov 25, 2022
@luna beautifull, in its own way :)
Show threadErtainNov 25, 2022
@luna Nice one.
Show threadJonathan β€˜theJPster’ PallantNov 25, 2022
@luna I'm making the cross face but I'm secretly quite impressed.
Show threadnex  Nov 25, 2022
@luna awesome! Took a while to understand why this works πŸ‘πŸ˜…
Show thread^||^Nov 25, 2022
@luna "this" cannot be explained with C, only with Java 🀭
Show thread^||^Nov 26, 2022
@luna ... and C++
Show threadAras PranckevičiusNov 25, 2022

@luna Luna.

(This is most excellent)

Show threadscriptwelder Nov 25, 2022
@luna OMG πŸ˜‚
Show threadThomas StΓΌfeNov 25, 2022
@luna Wll done! First line freaked me out until I read the spec...
Show threadRyan ✨ PavlikNov 25, 2022
@luna this is so cursed but lovely...
Show threadLightning Bjornsson*  Nov 25, 2022
@luna that isn't reflection
Show threadice.cream.assassinNov 25, 2022
@luna k that is just plain gorgeous.
Show threadDavid β€˜Bombe’ RodenNov 25, 2022
@luna πŸ˜‚
Show threadChris [list of emoji]Nov 25, 2022

@luna

It works because the C preprocessor ignores the trailing text after a directive. (I had *no idea* that this works, and I've been developing C code since the late 80s.)

Everything else works because the relevant /* and */ sequences comment stuff out.

Show threadChris [list of emoji]Nov 25, 2022

@luna

*standing ovation*

Show threadR. L. Dane  Nov 25, 2022

@luna

That's pretty special. :D

Show threadevolNov 25, 2022
@luna bonus points for the ideal font πŸ‘Œ
Show threadϻค𝔬ᑭNov 25, 2022

@luna

  This is truly art

Show thread[object Object]Nov 25, 2022
@luna @gsuberland I think when people say that, they mean that this isn't "true" reflection: the ordering of letters is reversed but not the glyphs.
Show threadKofu has movedNov 25, 2022
@luna this is so good it could've been a winning entry at the IOCCC
Show threadAurynn ShawNov 25, 2022
@luna Luna what the hell
Show threadAndreaNov 26, 2022
@luna @GyrosGeier Hey, finding your own code in memory and decompiling it is a perfectly cromulent form of reflection too :P
Show threadmiXsedNov 26, 2022

@luna
I find myself staring at that code for minutes...🀩 This ist mindblowing! I'm really impressed.

Even more since I understood why the first line compiles. 😜

Show threadMaxNov 26, 2022
@luna that is far too clever, I like it!
Show threadDaria AndreaNov 26, 2022
@luna brilliant reflective programming πŸ”πŸ˜Ž
Show threadPeter BarnesNov 28, 2022
@luna Nice!
Show threadI Can't Believe It's Not Zero!Nov 28, 2022
@luna 😠
Show threadFrancesco BiscaniNov 29, 2022

@luna

Take my angry boost.

Show threadLRDec 1, 2022

@luna *squints eyes*

remove the comment characters, and your HOUSE OF LIES collapses

Show threadthe account formerly known as LunaDec 1, 2022
@lritter yes yes, they’re load-bearing comments
Show threadLRDec 1, 2022
@luna haha, i love that term
Show threadLRDec 1, 2022
@luna however #include not parsing anything that follows the one argument it cares about makes me feel less bad about my own parsers
Show threadJohn KaniarzDec 1, 2022

@lritter @luna This reminds me of the palindrome entry in the 1987 IOCCC. The #include trick here might be what it takes to get the entry to compile on modern C compilers. It assumes putc exists for free and doesn’t include stdio.h

https://www.ioccc.org/1987/westley/westley.c

Show threadrobisnowtiredDec 1, 2022
@luna Go sit in a corner. You know what you've done.
Show threadDavid AmadorDec 1, 2022
@luna hold up this actually compiles :O