flow into dotnet/runtime main blocked

[lewing]

Runtime hasn't taken a new roslyn build for several weeks, the failure described here is blocking code flow.

Version Used:

The roslyn flow into dotnet/runtime is breaking on dotnet/runtime#81164

Steps to Reproduce:

See linked issue

Diagnostic Id:

`src/libraries/System.Text.Json/tests/Common/TestClasses/TestClasses.Constructor.cs(2394,9): error CS8078: (NETCORE_ENGINEERING_TELEMETRY=Build) An expression is too long or complex to compile``

Expected Behavior:

See the discussion

Actual Behavior:

CS8078 when compiling a test that uses a 1000 parameter constructor

[AlekseyTs]

I am not able to to reproduce the issue for a record with a 1000 parameters. Got an error for 1720 parameters, no error for 1710 parameters. Here are several top frames:

>	Microsoft.CodeAnalysis.dll!Microsoft.CodeAnalysis.StackGuard.EnsureSufficientExecutionStack(int recursionDepth) Line 29	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 363	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranchCore(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 450	C#
 	Microsoft.CodeAnalysis.CSharp.dll!Microsoft.CodeAnalysis.CSharp.CodeGen.CodeGenerator.EmitCondBranch(Microsoft.CodeAnalysis.CSharp.BoundExpression condition, ref object dest, bool sense) Line 365	C#

We are trying to emit synthesized System.Boolean ClassWithManyConstructorParameters.Equals(ClassWithManyConstructorParameters? other).

It doesn't look like EmitCondBranch or EmitCondBranchCore were modified since 2018. However, we do have a deep recursion while emitting deeply nested conditional expression. Should consider switching to an alternative emit strategy instead.