[Issue 15575] New: Wrong value for static immutable struct with union

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15575

          Issue ID: 15575
           Summary: Wrong value for static immutable struct with union
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: cpicard at openmailbox.org

DMD v2.069, no flag, crashes when dealing with the following code:

-----------------------------------------------------------------------------

struct Color {
    union {
        ubyte[4] components;

        struct {
            ubyte r;
            ubyte g;
            ubyte b;
            ubyte a;
        }
    }

    this(ubyte red, ubyte green, ubyte blue, ubyte alpha=255) {
        if(__ctfe)
            this.components[0] = cast(ubyte) red;
        else
            this.r = cast(ubyte) red;
        this.g = cast(ubyte) green;
        this.b = cast(ubyte) blue;
        this.a = cast(ubyte) alpha;
    }
}

static immutable colorA = Color(0xcc, 0x88, 0x00);

void main(string[] args) {
    pragma(msg, colorA.components);
    // [cast(ubyte)204u, cast(ubyte)0u, cast(ubyte)0u, cast(ubyte)0u]

    pragma(msg, colorA);
    // Color([cast(ubyte)204u, cast(ubyte)0u, cast(ubyte)0u, cast(ubyte)0u], ,
    //       cast(ubyte)136u, cast(ubyte)0u, cast(ubyte)255u, )
}

-----------------------------------------------------------------------------

The message is:

    t.d(32): Error: Internal Compiler Error: null field components
    test.d(32):     while evaluating pragma(msg, colorA.components)
    Color(, , cast(ubyte)136u, cast(ubyte)0u, cast(ubyte)255u, )

LDC doesn't produce an error message but produces garbage instead.

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