Modules are pure.

libsolidity/analysis/TypeChecker.cpp

@@ -2704,6 +2704,8 @@ bool TypeChecker::visit(MemberAccess const& _memberAccess)
 				annotation.isPure = _memberAccess.expression().annotation().isPure;
 		}
 	}
+	else if (exprType->category() == Type::Category::Module)
+		annotation.isPure = _memberAccess.expression().annotation().isPure;
 
 	// TODO some members might be pure, but for example `address(0x123).balance` is not pure
 	// although every subexpression is, so leaving this limited for now.
@@ -3053,7 +3055,8 @@ bool TypeChecker::visit(Identifier const& _identifier)
 	}
 	else if (dynamic_cast<TypeType const*>(annotation.type))
 		annotation.isPure = true;
-
+	else if (dynamic_cast<ModuleType const*>(annotation.type))
+		annotation.isPure = true;
 
 	// Check for deprecated function names.
 	// The check is done here for the case without an actual function call.

libsolidity/codegen/ExpressionCompiler.cpp

@@ -1718,6 +1718,16 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 			solAssert(false, "Illegal fixed bytes member.");
 		break;
 	}
+	case Type::Category::Module:
+	{
+		Type::Category category = _memberAccess.annotation().type->category();
+		solAssert(
+			category == Type::Category::TypeType ||
+			category == Type::Category::Module,
+			""
+		);
+		break;
+	}
 	default:
 		solAssert(false, "Member access to unknown type.");
 	}
@@ -1933,6 +1943,10 @@ void ExpressionCompiler::endVisit(Identifier const& _identifier)
 	{
 		// no-op
 	}
+	else if (dynamic_cast<ImportDirective const*>(declaration))
+	{
+		// no-op
+	}
 	else
 	{
 		solAssert(false, "Identifier type not expected in expression context.");

test/libsolidity/syntaxTests/imports/import_access_struct.sol

@@ -0,0 +1,14 @@
+==== Source: a ====
+struct S { uint x; }
+==== Source: b ====
+import "a" as A;
+struct T { uint x; }
+contract C {
+    function f() public pure {
+        T;
+        A.S;
+    }
+}
+// ----
+// Warning: (b:90-91): Statement has no effect.
+// Warning: (b:101-104): Statement has no effect.

test/libsolidity/syntaxTests/imports/transitive.sol

@@ -0,0 +1,15 @@
+==== Source: a ====
+struct S { uint[2] mS; }
+==== Source: b ====
+import "a" as A;
+struct T { A.S[2] mT; }
+==== Source: c ====
+pragma experimental ABIEncoderV2;
+import "b" as B;
+contract C {
+    function f(B.T memory y, B.A.S memory z) public pure returns (uint, uint) {
+        z = B.A.S([uint(2), 3]);
+        y = B.T([z, z]);
+        return (y.mT[0].mS[0], z.mS[0]);
+    }
+}