Infer delegate types with -langversion:10 (and above) only#55232
Merged
cston merged 2 commits intodotnet:release/dev17.0from Jul 29, 2021
Merged
Infer delegate types with -langversion:10 (and above) only#55232cston merged 2 commits intodotnet:release/dev17.0from
cston merged 2 commits intodotnet:release/dev17.0from
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…otnet#53241)" (dotnet#53466)" This reverts commit 7d461ed.
RikkiGibson
reviewed
Jul 29, 2021
| // System.Console.Write((null, () => 1) == (default, default)); | ||
| Diagnostic(ErrorCode.ERR_AmbigBinaryOps, "(null, () => 1) == (default, default)").WithArguments("==", "<null>", "default").WithLocation(6, 30), | ||
| // (6,37): error CS8773: Feature 'inferred delegate type' is not available in C# 9.0. Please use language version 10.0 or greater. | ||
| // (6,30): error CS0019: Operator '==' cannot be applied to operands of type 'lambda expression' and 'default' |
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I wonder if later on (i.e. not in this PR/release) it will be practical to devise some way to still give LangVersion diagnostics. For example, by checking again at the point we give a conversion error if a valid conversion "would have" existed in the later language version.
RikkiGibson
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Jul 29, 2021
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Approved to merge whenever CI is green |
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Do not infer delegate types for lambda expressions and method groups when compiling with
-langversion:9and earlier, to restore the binding behavior from C#9 for those cases.This matches the behavior in 16.11 where inferring delegate types is conditional on
-langversion(see #53241). That behavior was reverted in commit 7d461ed for earlier 17.0 previews, and is now re-applied.See LDM notes: lambda-conversion-to-systemdelegate.