.NET 9 Preview.5, Preview.6, Preview.7 C# compiler crashes on LINQ expression with string interpolation
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SergeiPavlov
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Preview.5, Preview.6, Preview.7 crashes on LINQ expression with string interpolation
SergeiPavlov
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Preview.5, Preview.6, Preview.7 crashes on LINQ expression with string interpolationPreview.5, Preview.6, Preview.7 C# compiler crashes on LINQ expression with string interpolation
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The string interpolation is handled internally as collection-expression conversion to a readonly span (a debug assert is also triggered). Currently: using System.Collections.Generic;
using System.Linq;
class Program
{
static IQueryable<string> GetStrings() => null;
public static void Main() =>
GetStrings().Select(o => string.Format("{0} {1} {2} {3}", o, o, o, o));
}For expression trees we could lower it to (no ref struct allowed): using System.Collections.Generic;
using System.Linq;
class Program
{
static IQueryable<string> GetStrings() => null;
public static void Main() =>
GetStrings().Select(o => string.Format("{0} {1} {2} {3}", new object[] { o, o, o, o }));
}But it would be maybe better to handle it in the invocation binding. |
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It sounds like a usage of a non-array params collection is making its way to an expression tree without triggering an error. The following method is supposed to detect the situation: At the moment there is no clarity how exactly a collection expression is getting through. Understanding that should be the next step in instigation of this issue. |
Could you please provide more details?
Where exactly this handling is happening?
What does assert check? Where it is in the code? What the call stack looks like? |
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The collection-conversion comes to play at (here we lower and assume overload resolution to pick the right one): This is great because we have multiple overloads, with and without params. Overload resolution chooses the best one. And this allows the same code for less than 4 parameters, too. The problem arises now for the params overload because we have 2 of them and the span overload is better.
It is here The callstack is: |
Well, as we can see this approach is fragile and/or lacks proper validation of the result that it produces. |
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Other parts of |
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I think it would be good to understand what overloads |
jaredpar
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New Feature - Collection Expressions
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More detailed call stack for the following scenario: Call stack: |
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Here is a unit-test that hits the same exception once all debug asserts on the way are disabled: |
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Version Used:
.NET 9 SDK 9.0.100-preview.5.24307.3
tried also Preview.6 and today's Preview.7
Steps to Reproduce:
Following code:
with
.csproj:Diagnostic Id:
Expected Behavior:
Successful build
Actual Behavior:
Compiler crash
(does work without
<LangVersion>Preview</LangVersion>setting)The text was updated successfully, but these errors were encountered: