Check generic construction diagnostics for stackalloc to span conversions #25131
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cc @dotnet/roslyn-compiler for review |
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cc @AlekseyTs as you first raised this in a different PR. |
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@OmarTawfik May we sync |
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@alrz. Yes. The owner of the feature branch can update it from 15.7.x once approved and merged. |
jcouv
approved these changes
Mar 1, 2018
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Yes. We should check with compat council. It is highly unlikely though that this breaks any functional code. Allowing Span in stackalloc would easily result in a GC holes and heap corruption. |
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@jaredpar for ask mode approval. |
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@jaredpar can you please take a look? |
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approved |
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Closes #25086
Closes #25038
There is a bug in C# 15.5, where during the conversion of a
stackallocexpression to aSpan<T>object creation, the type parameter construction and constraints matching were not checked during binding.Fixing this for 15.7 is a breaking change, because an expression of
stackalloc T [count]would be legal even ifTwas not legal to initializeSpan<T>with. We would previously emit IL even if it would cause run time exceptions. do believe that the scope is small enough for us to take the breaking change though.