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digitalmars.D.learn - std.conv.ConvException from double to uint64_t, but only locally in a

reply drathier <forum.dlang.org fi.fo> writes:
I'm getting a crash when I'm converting a double to an uint64_t.

```
std.conv.ConvException /usr/local/opt/dmd/include/dlang/dmd/std/conv.d(2054):
Value (1596) does not match any member value of enum '__c_ulonglong'
```

I've narrowed down the code to this:
```
static import std.conv;
double thing = 42.0;
std.conv.to!(uint64_t)(thing);
```
which works just fine on https://run.dlang.io/ or in a 
single-file dmd invocation. When I compile and run it locally on 
my mac as part of a specific large app using dub, it always 
crashes like this.

Where would I even start debugging this?

DMD64 D Compiler v2.093.0
DUB version 1.22.0, built on Jul  9 2020
Aug 04 2020
next sibling parent reply drathier <forum.dlang.org fi.fo> writes:
 ```
 std.conv.ConvException /usr/local/opt/dmd/include/dlang/dmd/std/conv.d(2054):
Value (1596) does not match any member value of enum '__c_ulonglong'
 ```


well,
```
std.conv.ConvException /usr/local/opt/dmd/include/dlang/dmd/std/conv.d(2054):
Value (42) does not match any member value of enum '__c_ulonglong'
```
but the specific value doesn't matter
Aug 04 2020
parent reply drathier <forum.dlang.org fi.fo> writes:
On Tuesday, 4 August 2020 at 17:37:56 UTC, drathier wrote:

 ```
 std.conv.ConvException /usr/local/opt/dmd/include/dlang/dmd/std/conv.d(2054):
Value (1596) does not match any member value of enum '__c_ulonglong'
 ```


 well,
 ```
 std.conv.ConvException /usr/local/opt/dmd/include/dlang/dmd/std/conv.d(2054):
Value (42) does not match any member value of enum '__c_ulonglong'
 ```
 but the specific value doesn't matter


full stack trace:
```
std.conv.ConvException /usr/local/opt/dmd/include/dlang/dmd/std/conv.d(2054):
Value (42) does not match any member value of enum '__c_ulonglong'
----------------
source/app.d:864  safe core.stdc.config.__c_ulonglong 
std.conv.toImpl!(core.stdc.config.__c_ulonglong, 
double).toImpl(double) [0x10fa540f8]
source/app.d:864  safe core.stdc.config.__c_ulonglong 
std.conv.to!(core.stdc.config.__c_ulonglong).to!(double).to(double)
[0x10fa54072]
source/app.d:262 int app.processFromOffset(std.socket.Socket, 
app.KafkerMode, app.RuntimeState, core.stdc.config.__c_ulonglong, 
core.stdc.config.__c_ulonglong) [0x10f9d06b5]
source/app.d:175 _Dmain [0x10f9cfcae]
```
Aug 04 2020
parent reply drathier <forum.dlang.org fi.fo> writes:
Replaced all mentions of uint64_t with ulong, and now it works. 
Must have an enum called uint64_t defined somewhere in a library 
I depend on or something? Really wish this was clearer.
Aug 04 2020
parent Nathan S. <no.public.email example.com> writes:
On Tuesday, 4 August 2020 at 17:49:56 UTC, drathier wrote:

 Replaced all mentions of uint64_t with ulong, and now it works. 
 Must have an enum called uint64_t defined somewhere in a 
 library I depend on or something? Really wish this was clearer.


BTW I believe the reason that `uint64_t` is an enum (which is 
being imported by "import std" but isn't converting) solely on 
macOS/iOS is for compatibility with C++ name mangling.
Aug 04 2020
prev sibling parent reply Steven Schveighoffer <schveiguy gmail.com> writes:
On 8/4/20 1:36 PM, drathier wrote:

 I'm getting a crash when I'm converting a double to an uint64_t.
 
 ```
 std.conv.ConvException /usr/local/opt/dmd/include/dlang/dmd/std/conv.d(2054): 
 Value (1596) does not match any member value of enum '__c_ulonglong'
 ```
 
 I've narrowed down the code to this:
 ```
 static import std.conv;
 double thing = 42.0;
 std.conv.to!(uint64_t)(thing);
 ```
 which works just fine on https://run.dlang.io/ or in a single-file dmd 
 invocation. When I compile and run it locally on my mac as part of a 
 specific large app using dub, it always crashes like this.
 
 Where would I even start debugging this?
 
 DMD64 D Compiler v2.093.0
 DUB version 1.22.0, built on Jul  9 2020
 


So a common way to typedef something is to use enum:

enum uint64_t : ulong;

This gives you a new type that works pretty much just like ulong, but 
will not implicitly convert from ulong.

However, std.conv.to is likely interpreting this as an enumeration type, 
where it has to match one of the enum members. But since this isn't an 
enumeration in the standard way, it fails (it has no members!)

This code reproduces the problem on run.dlang.io:

void main()
{
     import core.stdc.config;
     import std.conv;
     auto x = 0.5;
     auto y = x.to!__c_ulonglong;
}

Note the code in druntime which defines __c_ulonglong: 
https://github.com/dlang/druntime/blob/0db2e65bba7cc319309bd32957763882870d5b03/src/core/stdc/config.d#L121

I'll file a bug.

-Steve
Aug 04 2020
parent Steven Schveighoffer <schveiguy gmail.com> writes:
On 8/4/20 2:15 PM, Steven Schveighoffer wrote:

 I'll file a bug.


https://issues.dlang.org/show_bug.cgi?id=21112

-Steve
Aug 04 2020