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Add `CastExp.toLvalue` dip1000 error if implicit pointer conversion would fail
From https://dlang.org/spec/expression.html#.define-lvalue
The following expressions, and no others, are called lvalue expressions or lvalues ... cast(U) expressions applied to lvalues of type T when T* is implicitly convertible to U*; cast() and cast(qualifier list) when applied to an lvalue.
The first rule was not enforced by dmd. The second rule contradicts the point of the first rule. It ~~should~~ perhaps could be updated to work in the same way.
Fixes Issue 23530 - casting immutable away allowed in safe.
Edit: Changed to dip1000 error rather than obsolete warning.
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Bugzilla references
Auto-close | Bugzilla | Severity | Description |
---|---|---|---|
✓ | 23530 | critical | casting immutable away allowed in safe |
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This makes _dupCtfe
get inferred @system
even though there's no cast:
foreach (ref e; a)
res ~= e; // offending line
Not sure how to avoid that. It lowers to:
for (; __key3 < __r2.length; __key3 += 1LU)
{
const ref const(S) e = __r2[__key3];
(ref S __appendtmp4 = e;) , (_d_arrayappendcTX(res, 1LU) , res[res.length - 1LU] = __appendtmp4 , res);
}
But still there's no cast and _d_arrayappendcTX
is @trusted
anyway.
I'm not sure where the cast expression comes from when calling _dupCtfe
:
foreach (ref e; a)
res ~= e; // offending line
I tried to work around that by ignoring any casts in functions being interpreted at compile-time, but I'm clearly not detecting that correctly. Using SCOPE.ctfeBlock
doesn't work either.
Closing in favour of https://github.com/dlang/dmd/pull/16315#issuecomment-2016931657