Allow passing sized array to unsized array parameter. (#4744)

1 files changed, 25 insertions, 0 deletions

diff --git a/source/slang/slang-check-conversion.cpp b/source/slang/slang-check-conversion.cpp
index 00625d5f4..fafefa9dd 100644
--- a/source/slang/slang-check-conversion.cpp
+++ b/source/slang/slang-check-conversion.cpp
@@ -750,6 +750,31 @@ namespace Slang
             return true;
         }
 
+        // Allow implicit conversion from sized array to unsized array when
+        // calling a function.
+        // Note: we implement the logic here instead of an implicit_conversion
+        // intrinsic in the stdlib because we only want to allow this conversion
+        // when calling a function.
+        //
+        if (site == CoercionSite::Argument)
+        {
+            if (auto fromArrayType = as<ArrayExpressionType>(fromType))
+            {
+                if (auto toArrayType = as<ArrayExpressionType>(toType))
+                {
+                    if (fromArrayType->getElementType()->equals(toArrayType->getElementType())
+                        && toArrayType->isUnsized())
+                    {
+                        if (outToExpr)
+                            *outToExpr = fromExpr;
+                        if (outCost)
+                            *outCost = kConversionCost_SizedArrayToUnsizedArray;
+                        return true;
+                    }
+                }
+            }
+        }
+
         // Another important case is when either the "to" or "from" type
         // represents an error. In such a case we must have already
         // reporeted the error, so it is better to allow the conversion