Modifying global char[] initialized with dup of string literal causes segfault

[pbackus]

As of DMD v2.111.0, compiling and executing the following program causes a segmentation fault:

char[] a = "foo".dup;

void main()
{
    a[0] = 'b'; // Error: program killed by signal 11
}

Examining the compiled code with objdump reveals that this happens because the data for the array is stored in read-only memory, even though the array's element type is mutable:

$ objdump -d -j .rodata.str1.1 bug.o

bug.o:     file format elf64-x86-64


Disassembly of section .rodata.str1.1:

0000000000000000 <_TMP0>:
   0:	66 6f 6f 00                                         foo.

If the array is initialized with an array literal (['f', 'o', 'o']) instead of a .duped string literal, the program runs successfully to completion.

[ibuclaw]

Not a regression. The same happens with DMD 2.076.0.