[SDC] Allow inferring template parameter from type of template value parameter

[dlangBugzillaToGithub]

Shammah Chancellor reported this on 2015-03-28T16:50:15Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=14359

CC List

• ag0aep6g
• yebblies
• Yuxuan Shui

Description

```
> dmd test0154.d
test0154.d(6): Error: undefined identifier T
```

```test0154.d
//T compiles:yes
//T has-passed:yes
//T retval:25
// template value parameter

auto foo(T U, T)() {
	return cast(int) (U + T.sizeof);
}

int main() {
	return foo!true() + foo!10() + foo!I();
}

enum I = 5;
```

[dlangBugzillaToGithub]

k.hara.pg commented on 2015-03-29T04:56:15Z

How SDC works for following codes?

auto foo(T u, T)() {
   return typeof(u).stringof;
}

pragma(msg, foo(1));         // T is deduced to int ... it's reasonable.

pragma(msg, foo(1, int));    // typeof(1) is int by default, so it might be accepted

pragma(msg, foo(1, long));   // typeof(u) will be long, or conflict happens?
pragma(msg, foo(1, double)); // typeof(u) will be double, or conflict happens?

pragma(msg, foo(1, string)); // definitely conflicts

[dlangBugzillaToGithub]

yebblies commented on 2015-04-11T06:29:44Z

Is this supposed to work?  Change back to normal if so.

[dlangBugzillaToGithub]

yebblies commented on 2015-04-11T06:40:10Z

*** Issue 14362 has been marked as a duplicate of this issue. ***

[dlangBugzillaToGithub]

nick (@ntrel) commented on 2018-11-30T12:57:20Z

*** Issue 17279 has been marked as a duplicate of this issue. ***