[AST] Ensure that type-checked Patterns always have types set

Kind of amazed we don't already have this. Add an
ASTVerifier assertion to ensure type-checked patterns
always have types set.

Author: hamishknight

lib/AST/ASTVerifier.cpp

@@ -486,7 +486,7 @@ class Verifier : public ASTWalker {
       return true;
     }
     bool shouldVerifyChecked(Stmt *S) { return true; }
-    bool shouldVerifyChecked(Pattern *S) { return S->hasType(); }
+    bool shouldVerifyChecked(Pattern *S) { return true; }
     bool shouldVerifyChecked(Decl *S) { return true; }
 
     // Only verify functions if they have bodies we can safely walk.
@@ -582,8 +582,14 @@ class Verifier : public ASTWalker {
         return;
       }
     }
+    void verifyChecked(Pattern *P) {
+      if (!P->hasType()) {
+        Out << "pattern has no type\n";
+        P->dump(Out);
+        abort();
+      }
+    }
     void verifyChecked(Stmt *S) {}
-    void verifyChecked(Pattern *P) { }
     void verifyChecked(Decl *D) {}
 
     void verifyChecked(Type type) {