[Issue 21209] New: scope attribute inference with does not work well with foreach

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21209

          Issue ID: 21209
           Summary: scope attribute inference with does not work well with
                    foreach
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: rightfold+bugzilla+dlang at gmail.com

The following program does not compile:

---
$ cat main.d
void foo()(const(char)[] cs)
{
    foreach (c; cs)
        bar(c);
}

@safe
void bar(char c)
{
}

@safe
void main()
{
    char[10] cs;
    foo(cs); // line 16
}
$ dmd -dip1000 main.d
main.d(16): Error: reference to local variable `cs` assigned to non-scope
parameter `cs` calling example.foo!().foo
---

By manually adding the scope attribute to the cs parameter, the program
compiles. But it is expected that DMD infers this from the body of the foo
function, as it is a template.

Verified with DMD 2.092.0 and LDC 1.23.0.

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