Infer delegate types with -langversion:10 (and above) only #55232
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…otnet#53241)" (dotnet#53466)" This reverts commit 7d461ed.
RikkiGibson
reviewed
Jul 29, 2021
| @@ -1358,12 +1358,9 @@ static void Main() | |||
| // (6,30): error CS0034: Operator '==' is ambiguous on operands of type '<null>' and 'default' | |||
| // 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
approved these changes
Jul 29, 2021
|
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.