[Issue 23607] New: ICE caused by an invalid pipline involving std.conv.to!string

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23607

          Issue ID: 23607
           Summary: ICE caused by an invalid pipline involving
                    std.conv.to!string
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Keywords: ice
          Severity: regression
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: b2.temp at gmx.com

this causes an ICE instead of producing normal error messages

```
import std.conv;
alias comb = to!string.bad!"";
```

accoring to run.dlang it's a 2.099 reg:

```
2.068.2 to 2.072.2: Failure with output: onlineapp.d(2): Error: template
identifier 'bad' is not a member of template 'std.conv.to!string.to(A...)(A
args) if (!isRawStaticArray!A)'
2.073.2 to 2.078.3: Failure with output: onlineapp.d(2): Error: template
identifier 'bad' is not a member of template 'std.conv.to!string.to(A...)(A
args) if (A.length > 0)'
2.079.1 to 2.098.1: Failure with output: onlineapp.d(2): Error: template
identifier `bad` is not a member of template `std.conv.to!string.to(A...)(A
args) if (A.length > 0)`
Since      2.099.1: Failure with output: Error: unknown, please file report on
issues.dlang.org
```

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