Misleading error message: Cannot deduce function

[dlangBugzillaToGithub]

andre reported this on 2015-02-23T15:55:24Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=14217

CC List

• nick (@ntrel)

Description

The following source code doesn't compile because in the lambda 'a.bar' is written instead of 'a.foo'.

import std.algorithm: canFind;

struct A { string foo; }

void main()
{
	A[] arr;
	arr.canFind!(a => a.bar);
}

It isn't clear from the error message, that the property'bar' is causing the error:

source\app.d(9): 
Error: template std.algorithm.canFind cannot deduce function
from argument types !((a) => a.bar)(A[]), candidates are:
C:\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(11266):        std.algorithm.canFind(alias pred = "a == b")

I would expect an error message: no property 'bar' for type 'A'

[dlangBugzillaToGithub]

nick (@ntrel) commented on 2018-06-23T13:52:38Z

Like Issue 13683, this is caused by canFind's template constraint rather than dmd. It could be changed to use a static assert, so that the error mentions that the lambda can't take an A.