From 66f80abce84078323c49e7b767c75dba2b9122a8 Mon Sep 17 00:00:00 2001
From: Julien Couvreur <jcouv@users.noreply.github.com>
Date: Tue, 15 Oct 2024 15:47:15 -0700
Subject: [PATCH] Clarify the compiler's policy towards well-known
 types/members

---
 docs/compilers/CSharp/Deviations from Standard.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/docs/compilers/CSharp/Deviations from Standard.md b/docs/compilers/CSharp/Deviations from Standard.md
index b7f6077d32e77..66cee1e3a9ca5 100644
--- a/docs/compilers/CSharp/Deviations from Standard.md	
+++ b/docs/compilers/CSharp/Deviations from Standard.md	
@@ -70,3 +70,10 @@ interface I1 { void M() { } }
 interface I2 { int M => 0;   }
 interface I : I1, I2 { }
 ```
+
+# Assumptions about well-known types/members
+
+The compiler is free to make assumptions about the shape and behavior of well-known types/members.
+It may not check for unexpected constraints, `Obsolete` attribute, or `UnmanagedCallersOnly` attribute.
+It may perform some optimizations based on expectations that the types/members are well-behaved.
+Note: the compiler should remain resilient to missing well-known types/members.