• d-bugmail puremagic.com (32/32) Nov 09 2019 https://issues.dlang.org/show_bug.cgi?id=20377

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=20377

          Issue ID: 20377
           Summary: extern(C) void main(string[] args) has invalid 'args'
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: mipri minimaltype.com

The following complete program succeed when run with no arguments.
What it should do is fail on the second assert.

extern(C) void main(string[] args) {
    import core.stdc.stdio: printf;

    assert(args.length == 1);
    assert(args[0].ptr == null);
}

When 'extern(C)' is removed, this code fails as args[0] contains the
path used to invoke the program, as provided by the OS.

I noticed this when trying to write an extremely simple C program in D,
with -betterC, where I spent more than 20 minutes being perplexed by
'impossible' NULL dereferences. The behavior comes with the extern(C)
however, and doesn't require a -betterC flag. This behavior is observed
with LDC 1.15.0 and DMD64 D Compiler v2.086.1, and with the nightly DMD
build of v2.089.0-rc.1-master-2bbd37b

extern(C) void main(int argc, char **argv) works fine, but I argue if
string[] args isn't supported, compilation should fail with an error
instead of providing the current behavior.

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