[Issue 16672] Deprecate "block only" delegate syntax

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16672

Nick Treleaven <nick at geany.org> changed:

           What    |Removed                     |Added
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                 CC|                            |nick at geany.org

--- Comment #1 from Nick Treleaven <nick at geany.org> ---
Link to most recent question on the forum:
http://forum.dlang.org/post/pcbqcrujjewmdptuggsy@forum.dlang.org

Andrei uncovered this gem:

int j;
for({j=2; int d = 3; } j+d<7; {j++; d++;}) {
}

http://forum.dlang.org/thread/nud21i$o29$1@digitalmars.com

As he explains, the Initialize part of `for` grammar specially allows
BlockStatement, but the Increment part is just an expression. So {j++; d++;} is
an expression, *not* a BlockStatement, which parses as a nullary delegate,
which is never called! Hence infinite loop.

Andrei also mentions an alternative fix:

> Another possibility is to disallow an ExpressionStatement that 
> consists solely of a lambda. There is precedent for that, e.g. 
> the statement "1 + 1;" is disallowed. -- Andrei

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