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digitalmars.D - CTFE bug?

reply Manu <turkeyman gmail.com> writes:
Does anyone understand: https://issues.dlang.org/show_bug.cgi?id=19598
And are there any known workarounds?
Jan 20
parent reply Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:
On Monday, 21 January 2019 at 00:44:02 UTC, Manu wrote:
 Does anyone understand: 
 https://issues.dlang.org/show_bug.cgi?id=19598 And are there 
 any known workarounds?
Defining an opAssign for S seems to work: int test() { struct S { int x; void opAssign(S s) { x = s.x; } } S t1; S* n1 = new S; *n1 = t1; return 10; } pragma(msg, test()); Fascinatingly, it seems 'new' is doing something special in this code - replacing 'new S' with '&t1', things compile. Second workaround: create an array of S, then take the address of the first one: int test2() { struct S { int x; } S t1; S* n1 = &(new S[1])[0]; *n1 = t1; return 10; } pragma(msg, test2()); Now, as for why the simple, sensible code in the bug report doesn't work, I have no idea. It seems `new S` marks the block in some way that prevents regular assignment from working. -- Simen
Jan 20
parent Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:
On Monday, 21 January 2019 at 07:31:39 UTC, Simen Kjærås wrote:
 Now, as for why the simple, sensible code in the bug report 
 doesn't work, I have no idea. It seems `new S` marks the block 
 in some way that prevents regular assignment from working.
So I spent a little time looking into this. It seems assignToLvalue doesn't know how to deal with structs. I simply added this to dinterpret.d, around line 4026 (just before the "`%s` cannot be evaluated at compile time" block): else if (auto sle = e1.isStructLiteralExp()) { oldval = sle; } Now, is this a sufficient fix? I don't know. Does it break things elsewhere? I don't know. Does it work in this specific case, solving this specific problem? Sure does. -- Simen
Jan 21