[Issue 22427] New: betterC: casting an array causes linker error in string comparison.

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22427

          Issue ID: 22427
           Summary: betterC: casting an array causes linker error in
                    string comparison.
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: dave287091 at gmail.com

This reduced code fails to link. 
// foo.d
extern(C)
int main(){
    if("a" == "a")
        return 1;
    char[] p;
    auto a = cast(int[])p;
    return 0;
}

A linker error results:

Undefined symbols for architecture x86_64:
  "__D4core8internal5array8equality__T8__equalsTaTaZQoFNaNbNiNeMxAaMxQeZb",
referenced from:
      _main in foo.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Error: /usr/bin/cc failed with status: 1

The undefined symbol demangles to:
pure nothrow @nogc @trusted bool core.internal.array.equality.__equals!(char,
char).__equals(scope const(char[]), scope const(char[]))

I have verified this problem happens both with dmd and ldc2. ldc2 1.24 - 1.28
has the error. Older ldc do not. Current dmd has the error, I don’t know how
far back.

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