Fix failing System.Reflection.Emit tests (#17915)

Commit fceac03e82 removed a test from `TypeBuilder.SetConstantValue`
that is too strict when called from `ParameterBuilder`, but that both
`FieldBuilder` and `EnumBuilder` require. Add the same test back, but
in `FieldBuilder.SetConstant`.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/mscorlib/src/System/Reflection/Emit/FieldBuilder.cs b/src/mscorlib/src/System/Reflection/Emit/FieldBuilder.cs
index 2c4850921c..78a1ed5bb5 100644
--- a/src/mscorlib/src/System/Reflection/Emit/FieldBuilder.cs
+++ b/src/mscorlib/src/System/Reflection/Emit/FieldBuilder.cs
@@ -178,6 +178,13 @@ namespace System.Reflection.Emit
         {
             m_typeBuilder.ThrowIfCreated();
 
+            if (defaultValue == null && m_fieldType.IsValueType)
+            {
+                // nullable types can hold null value.
+                if (!(m_fieldType.IsGenericType && m_fieldType.GetGenericTypeDefinition() == typeof(Nullable<>)))
+                    throw new ArgumentException(SR.Argument_ConstantNull);
+            }
+
             TypeBuilder.SetConstantValue(m_typeBuilder.GetModuleBuilder(), GetToken().Token, m_fieldType, defaultValue);
         }