Index: flang/include/flang/Evaluate/characteristics.h
===================================================================
--- flang/include/flang/Evaluate/characteristics.h
+++ flang/include/flang/Evaluate/characteristics.h
@@ -123,9 +123,9 @@
   }
   template <typename A>
   static std::optional<TypeAndShape> Characterize(
-      const A *p, FoldingContext &context) {
-    if (p) {
-      return Characterize(*p, context);
+      A *ptr, FoldingContext &context) {
+    if (ptr) {
+      return Characterize(std::as_const(*ptr), context);
     } else {
       return std::nullopt;
     }
Index: flang/include/flang/Evaluate/tools.h
===================================================================
--- flang/include/flang/Evaluate/tools.h
+++ flang/include/flang/Evaluate/tools.h
@@ -262,9 +262,9 @@
 }
 
 // If an expression simply wraps a DataRef, extract and return it.
-// The Boolean argument controls the handling of Substring and ComplexPart
+// The Boolean arguments control the handling of Substring and ComplexPart
 // references: when true (not default), it extracts the base DataRef
-// of a substring or complex part, if it has one.
+// of a substring or complex part.
 template <typename A>
 common::IfNoLvalue<std::optional<DataRef>, A> ExtractDataRef(
     const A &, bool intoSubstring, bool intoComplexPart) {
Index: flang/lib/Evaluate/intrinsics.cpp
===================================================================
--- flang/lib/Evaluate/intrinsics.cpp
+++ flang/lib/Evaluate/intrinsics.cpp
@@ -3005,6 +3005,44 @@
         }
       }
     }
+  } else if (name == "transfer") { // 16.9.193
+    if (call.arguments.size() >= 2) {
+      auto source{characteristics::TypeAndShape::Characterize(
+          call.arguments[0], context)};
+      auto mold{characteristics::TypeAndShape::Characterize(
+          call.arguments[1], context)};
+      if (source && mold && mold->Rank() > 0 &&
+          evaluate::ToInt64(
+              evaluate::Fold(
+                  context, mold->MeasureElementSizeInBytes(context, false)))
+                  .value_or(1) == 0) {
+        if (auto sourceSize{evaluate::ToInt64(evaluate::Fold(
+                context, source->MeasureSizeInBytes(context)))}) {
+          if (*sourceSize > 0) {
+            context.messages().Say(
+                "Element size of MOLD= array may not be zero when SOURCE= is not empty"_err_en_US);
+            ok = false;
+          }
+        } else {
+          context.messages().Say(
+              "Element size of MOLD= array may not be zero unless SOURCE= is empty"_warn_en_US);
+        }
+      }
+      if (call.arguments.size() > 2) {
+        if (const Symbol *whole{
+                UnwrapWholeSymbolOrComponentDataRef(call.arguments[2])}) {
+          if (IsOptional(*whole)) {
+            context.messages().Say(
+                "SIZE= argument may not be the optional dummy argument '%s'"_err_en_US,
+                whole->name());
+            ok = false;
+          } else if (IsAllocatableOrPointer(*whole)) {
+            context.messages().Say(
+                "SIZE= argument that is allocatable or pointer must be present at execution; parenthesize to silence this warning"_warn_en_US);
+          }
+        }
+      }
+    }
   } else if (name == "ucobound") {
     return CheckDimAgainstCorank(call, context);
   }
Index: flang/lib/Semantics/check-call.cpp
===================================================================
--- flang/lib/Semantics/check-call.cpp
+++ flang/lib/Semantics/check-call.cpp
@@ -915,9 +915,9 @@
   parser::Messages buffer;
   parser::ContextualMessages messages{context.messages().at(), &buffer};
   RearrangeArguments(proc, actuals, messages);
+  evaluate::FoldingContext localContext{context, messages};
   if (buffer.empty()) {
     int index{0};
-    evaluate::FoldingContext localContext{context, messages};
     for (auto &actual : actuals) {
       const auto &dummy{proc.dummyArguments.at(index++)};
       if (actual) {
Index: flang/test/Semantics/transfer01.f90
===================================================================
--- /dev/null
+++ flang/test/Semantics/transfer01.f90
@@ -0,0 +1,31 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Check errors in TRANSFER()
+
+subroutine subr(o)
+  integer, intent(in), optional :: o
+  type empty
+  end type
+  type(empty) :: empty1(1)
+  real :: empty2(0)
+  character(0) :: empty3(1)
+  integer, pointer :: source(:)
+  integer, allocatable :: ia
+  integer, pointer :: ip
+  !ERROR: Element size of MOLD= array may not be zero when SOURCE= is not empty
+  print *, transfer(1., empty1)
+  print *, transfer(1., empty2) ! ok
+  !ERROR: Element size of MOLD= array may not be zero when SOURCE= is not empty
+  print *, transfer(1., empty3)
+  !WARNING: Element size of MOLD= array may not be zero unless SOURCE= is empty
+  print *, transfer(source, empty1)
+  print *, transfer(source, empty2) ! ok
+  !WARNING: Element size of MOLD= array may not be zero unless SOURCE= is empty
+  print *, transfer(source, empty3)
+  !ERROR: SIZE= argument may not be the optional dummy argument 'o'
+  print *, transfer(1., empty2, size=o)
+  !WARNING: SIZE= argument that is allocatable or pointer must be present at execution; parenthesize to silence this warning
+  print *, transfer(1., empty2, size=ia)
+  !WARNING: SIZE= argument that is allocatable or pointer must be present at execution; parenthesize to silence this warning
+  print *, transfer(1., empty2, size=ip)
+end
+