[clang][dataflow] Make `Value` and `StorageLocation` non-copyable

This makes it harder to misuse APIs that return references by
accidentally copying the results which could happen when assigning the
them to variables declared as `auto`.

Differential Revision: https://reviews.llvm.org/D127865

Reviewed-by: ymandel, xazax.hun

clang/include/clang/Analysis/FlowSensitive/StorageLocation.h

@@ -31,6 +31,12 @@ public:
 
   StorageLocation(Kind LocKind, QualType Type) : LocKind(LocKind), Type(Type) {}
 
+  // Non-copyable because addresses of storage locations are used as their
+  // identities throughout framework and user code. The framework is responsible
+  // for construction and destruction of storage locations.
+  StorageLocation(const StorageLocation &) = delete;
+  StorageLocation &operator=(const StorageLocation &) = delete;
+
   virtual ~StorageLocation() = default;
 
   Kind getKind() const { return LocKind; }

clang/include/clang/Analysis/FlowSensitive/Value.h

@@ -47,6 +47,12 @@ public:
 
   explicit Value(Kind ValKind) : ValKind(ValKind) {}
 
+  // Non-copyable because addresses of values are used as their identities
+  // throughout framework and user code. The framework is responsible for
+  // construction and destruction of values.
+  Value(const Value &) = delete;
+  Value &operator=(const Value &) = delete;
+
   virtual ~Value() = default;
 
   Kind getKind() const { return ValKind; }