June 16, 2022 [Issue 23192] New: Can't iterate aggregate fields with static foreach inside a member function | ||||
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https://issues.dlang.org/show_bug.cgi?id=23192 Issue ID: 23192 Summary: Can't iterate aggregate fields with static foreach inside a member function Product: D Version: D2 Hardware: All OS: All Status: NEW Severity: normal Priority: P1 Component: dmd Assignee: nobody@puremagic.com Reporter: snarwin+bugzilla@gmail.com As of DMD 2.100.0, the following program fails to compile: --- alias AliasSeq(Args...) = Args; struct S { int x; void fun() { static foreach (sym; AliasSeq!(S.x)) {} } } --- The error message is --- bug.d(8): Error: value of `this` is not known at compile time --- This is likely caused by the compiler treating the loop variable `sym` as an expression rather than an alias, since replacing the `static foreach` loop with an explicit alias declaration causes compilation to succeed: --- struct S { int x; void fun() { alias sym = S.x; // no error } } --- It is worth noting that the language spec's description of `static foreach` explicitly forbids this: > Within the i-th copy, the name of the static foreach variable > is bound to the i-th entry of the sequence, either as an enum > variable declaration (for constants) or an alias declaration > (for symbols). (In particular, static foreach variables are > never runtime variables.) https://dlang.org/spec/version.html#staticforeach -- |
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