Re: What exactly does the compiler switch -betterC do?

[Gary Willoughby via Digitalmars-d-learn]

On Monday, 20 June 2016 at 06:35:32 UTC, Jacob Carlborg wrote:
On 2016-06-19 21:53, Gary Willoughby wrote:
When compiling, what exactly does the -betterC flag do? The 
command help
says "omit generating some runtime information and helper 
functions" but
what does this really mean? Is there any specifics somewhere?


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It is intended to allow you to link an application without 
druntime. A Hello World using "extern(C) main" and printing 
using "printf" contains the following symbols on OS X:

00000000000000a8 S _D4main12__ModuleInfoZ
0000000000000068 T _D4main15__unittest_failFiZv
0000000000000018 T _D4main7__arrayZ
0000000000000040 T _D4main8__assertFiZv
00000000000000b5 s _TMP1
                 U __d_arraybounds
                 U __d_assert
                 U __d_unittest
0000000000000000 T _main
                 U _printf

If compiled with -betterC, it contains these:

0000000000000000 T _main
                 U _printf

I get significantly more symbols than that when compiling the 
following program any idea why?

    import core.stdc.stdio;

    extern(C) void main()
    {
        printf("Hello World!\n");
    }


$ rdmd --build-only --force -betterC -de -O -inline -release -w 
test.d
$ nm test