From 42dfffe7ae8e35e0e1f0119920bd5bac3ad373f4 Mon Sep 17 00:00:00 2001
From: Steve Otteson <sotteson@xoanan.com>
Date: Thu, 25 Feb 2021 14:03:02 -0800
Subject: [PATCH] Fixes #63: Make sure all parameters have at least one of
 in/out attributes. Fixes #139: Better deal with params marked with __RPC__
 SAL annotations

---
 .../ClangSharpSourceWinmdGenerator.cs         | 34 +++++++++++++++++++
 .../MetadataSyntaxTreeCleaner.cs              | 29 ++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/sources/ClangSharpSourceToWinmd/ClangSharpSourceWinmdGenerator.cs b/sources/ClangSharpSourceToWinmd/ClangSharpSourceWinmdGenerator.cs
index 9684d8e31..16d0ef12e 100644
--- a/sources/ClangSharpSourceToWinmd/ClangSharpSourceWinmdGenerator.cs
+++ b/sources/ClangSharpSourceToWinmd/ClangSharpSourceWinmdGenerator.cs
@@ -1754,6 +1754,40 @@ public Parameter(ClangSharpSourceWinmdGenerator generator, IMethodSymbol methodS
                     parameterAttributes |= ParameterAttributes.Optional;
                 }
 
+                // If we don't have any in/out attributes, figure out some sensible values
+                if (parameterAttributes == ParameterAttributes.None)
+                {
+                    // https://github.com/microsoft/win32metadata/issues/63
+                    // * If it's a primitive or a COM pointer, it's In.
+                    // * If it's a pointer it's In, Out, unless it's marked Const, then only In.
+                    // * If it's a COM double pointer (e.g. IUnknown**), it's Out.
+                    parameterAttributes |= ParameterAttributes.In;
+                    if (paramType is IPointerTypeSymbol pointerTypeSymbol)
+                    {
+                        // If we're not pointing at an interface...
+                        if (!generator.IsSymbolInterface(pointerTypeSymbol.PointedAtType))
+                        {
+                            bool isConst = symbolAttrs.Any(a => a.AttributeClass.Name == "ConstAttribute");
+
+                            // Only add Out if it's not const
+                            if (!isConst)
+                            {
+                                parameterAttributes |= ParameterAttributes.Out;
+                            }
+                        }
+
+                        // If it's a double pointer...
+                        if (pointerTypeSymbol.PointedAtType is IPointerTypeSymbol doublePointedAtType)
+                        {
+                            // Only use "Out" if it's a double COM pointer
+                            if (generator.IsSymbolInterface(doublePointedAtType.PointedAtType))
+                            {
+                                parameterAttributes = ParameterAttributes.Out;
+                            }
+                        }
+                    }
+                }
+
                 this.Name = paramName;
                 this.Attrs = parameterAttributes;
                 this.Type = paramType;
diff --git a/sources/ClangSharpSourceToWinmd/MetadataSyntaxTreeCleaner.cs b/sources/ClangSharpSourceToWinmd/MetadataSyntaxTreeCleaner.cs
index e306ee1c7..5d8fb98cd 100644
--- a/sources/ClangSharpSourceToWinmd/MetadataSyntaxTreeCleaner.cs
+++ b/sources/ClangSharpSourceToWinmd/MetadataSyntaxTreeCleaner.cs
@@ -626,6 +626,35 @@ private SyntaxNode CreateAttributeListForSal(AttributeListSyntax cppAttrList)
                             isOut = true;
                             continue;
                         }
+                        else if (salAttr.P1.StartsWith("__RPC__"))
+                        {
+                            // TODO: Handle ecount, xcount and others that deal with counts
+
+                            string[] parts = salAttr.P1.Split('_');
+                            foreach (var part in parts)
+                            {
+                                switch (part)
+                                {
+                                    case "in":
+                                        isIn = true;
+                                        break;
+
+                                    case "out":
+                                        isOut = true;
+                                        break;
+
+                                    case "inout":
+                                        isIn = isOut = true;
+                                        break;
+
+                                    case "opt":
+                                        isOpt = true;
+                                        break;
+                                }
+                            }
+
+                            break;
+                        }
                     }
 
                     if (salAttr.Name == "SAL_null" && salAttr.P1 == "__maybe")