https://issues.dlang.org/show_bug.cgi?id=21140

          Issue ID: 21140
           Summary: [REG2.086] Error on missed stack allocation for
                    closure for template
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: regression
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: bugzilla@digitalmars.com

Filed this as a new bug report instead of reopening https://issues.dlang.org/show_bug.cgi?id=20596

-------------------------------------------------------------

johanengelen@weka.io 2020-08-09 10:30:32 UTC writes:

Reopening, because the regression is not entirely fixed.
See this slightly modified testcase, where variable `s` is not explicitly
marked `scoped`. The compiler does not deduce `scope` for `s`. This used to
compile and not GC-allocate (<= 2.085) but no longer does.

```
 struct S(T) {
    void delegate() dg;

    this(scope void delegate() dg)
    {
        this.dg = dg;
    }
 }

 @nogc void fooTemplate() {
    int num;

    void foo() { int dummy = num; }

    auto s = S!int(&foo); // not explicitly defined as `scope`
 }
```

and:

Another example that fails compilation:

```
struct S(T) {
    void delegate() dg;

    this(scope void delegate() dg)
    {
        this.dg = dg;
    }
 }

// The explicit `scope` here is not used in `fooTemplate`
@nogc auto dosomething(scope S!int s)
{

}

@nogc auto fooTemplate() {
    int num;

    void foo() { int dummy = num; }

    dosomething(S!int(&foo));
}
```

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