From a89b9aee05dff74345a79f8fb4fe0fe3fdbb17ad Mon Sep 17 00:00:00 2001
From: qunyanm <unknown>
Date: Mon, 21 Mar 2016 11:45:14 -0700
Subject: Update module export error messages. Also for "import Y" if there is
 at least one exported view, but no exported view is marked as default, then
 it is an error.

---
 Source/Dafny/Resolver.cs            | 18 ++++++++++++++----
 Test/dafny0/ModuleExport.dfy        | 37 +++++++++++++++++++++++++++++++++++++
 Test/dafny0/ModuleExport.dfy.expect |  6 +++++-
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/Source/Dafny/Resolver.cs b/Source/Dafny/Resolver.cs
index d3b59b51..aa9ce148 100644
--- a/Source/Dafny/Resolver.cs
+++ b/Source/Dafny/Resolver.cs
@@ -742,7 +742,7 @@ namespace Microsoft.Dafny
               d.ExtendDecls.Add(extend);
               exportDependencies.AddEdge(d, extend);
             } else {
-              reporter.Error(MessageSource.Resolver, m.tok, s + " must be an export of" + m + " to be extended");
+              reporter.Error(MessageSource.Resolver, m.tok, s + " must be an export of " + m.Name + " to be extended");
             }
           }
           foreach (ExportSignature export in d.Exports) {
@@ -757,7 +757,7 @@ namespace Microsoft.Dafny
             } else if (sig.StaticMembers.TryGetValue(name, out member)) {
               export.Decl = member;
             } else {
-              reporter.Error(MessageSource.Resolver, d.tok, name + " must be a member of " + m + " to be exported");
+              reporter.Error(MessageSource.Resolver, d.tok, name + " must be a member of " + m.Name + " to be exported");
             }
           }
         }
@@ -779,7 +779,7 @@ namespace Microsoft.Dafny
           if (defaultExport == null) {
             defaultExport = decl;
           } else {
-            reporter.Error(MessageSource.Resolver, m.tok, "more than one default export declared: {0}, {1}", defaultExport, decl);
+            reporter.Error(MessageSource.Resolver, m.tok, "more than one default export declared in module {0}", m.Name);
           }
         }
         // fill in export signature
@@ -811,9 +811,14 @@ namespace Microsoft.Dafny
         }
       }
 
-      // set the default export if it exists, otherwise, default is export everything     
+      // set the default export if it exists
       if (defaultExport != null) {
         literalDecl.DefaultExport = defaultExport.Signature;
+      } else {
+        // if there is at least one exported view, but no exported view marked as default, then defaultExport should be null.
+        if (sortedDecls.Count > 0) {
+          literalDecl.DefaultExport = null;       
+        }
       }
     }
 
@@ -1437,6 +1442,11 @@ namespace Microsoft.Dafny
         // use the default export when the importing the root
         LiteralModuleDecl decl = (LiteralModuleDecl)root;
         p = decl.DefaultExport;
+        if (p == null) {
+          // no default view is specified. 
+          reporter.Error(MessageSource.Resolver, decl.tok, "no default export declared in module: {0}", decl.Name);
+          return false;
+        }
         return true;
       }
 
diff --git a/Test/dafny0/ModuleExport.dfy b/Test/dafny0/ModuleExport.dfy
index 81fe0ed5..1e69764f 100644
--- a/Test/dafny0/ModuleExport.dfy
+++ b/Test/dafny0/ModuleExport.dfy
@@ -65,4 +65,41 @@ module E {
     case Kiwi(x) => 7
 		case Orang => 8  // error
   } 
+}
+
+module F {
+  default export Public { f, h}
+	default export E1 { f, g}
+	export E2 extends Public2, E1 {T}		// error: Public2 is not a exported view of F
+  export Friend extends Public {g2, T}  // error: g2 is not a member of F
+	export Fruit {Data}
+
+  method h() {}
+  function f(): int { 818 }
+  function g() : int { 819 }
+	function k() : int { 820 }
+  
+	class T 
+	{
+	  static method l() {}
+	}
+
+	datatype Data = Lemon | Kiwi(int)
+}
+
+module G {
+  export Public { f, h}
+
+	method h() {}
+  function f(): int { 818 }
+  function g() : int { 819 }
+	function k() : int { 820 }
+}
+
+module H {
+  import G  // error: G has no default export
+}
+
+module I {
+  import G.Public  // OK
 }
\ No newline at end of file
diff --git a/Test/dafny0/ModuleExport.dfy.expect b/Test/dafny0/ModuleExport.dfy.expect
index c7444bdb..274c8f31 100644
--- a/Test/dafny0/ModuleExport.dfy.expect
+++ b/Test/dafny0/ModuleExport.dfy.expect
@@ -6,4 +6,8 @@ ModuleExport.dfy(42,11): Error: unresolved identifier: k
 ModuleExport.dfy(52,9): Error: unresolved identifier: g
 ModuleExport.dfy(53,9): Error: unresolved identifier: k
 ModuleExport.dfy(66,2): Error: member Orang does not exist in datatype Data
-8 resolution/type errors detected in ModuleExport.dfy
+ModuleExport.dfy(70,7): Error: Public2 must be an export of F to be extended
+ModuleExport.dfy(74,9): Error: g2 must be a member of F to be exported
+ModuleExport.dfy(70,7): Error: more than one default export declared in module F
+ModuleExport.dfy(90,7): Error: no default export declared in module: G
+12 resolution/type errors detected in ModuleExport.dfy
-- 
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