Unsafe[Mutable]Pointer<Pointee: ~Copyable & ~Escapable>

[atrick]

Allow unsafe pointer to access a ~Escapable Pointee.

This is a placeholder for review and to drive implementation of compiler Builtins. I suspect @lorentey will ultimately have a PR with the standard library additions.

[atrick]

@lorentey I'm using this PR to test compiler fixes. I think it's almost there and will land the few small compiler commits ASAP.

The hard problem: safely migrating all the signatures and symbols remains. In particular:

---

Backward compatibility with deprecated APIs:

test/Generics/slice_test.swift
test/Parse/pointer_conversion.swift.gyb
test/SILGen/borrow_from_load_expr.swift

error: unexpected warning produced: 'initialize(to:count:)' is deprecated: renamed to 'initialize(repeating:count:)'

Problem: -swift-version 4 does not appear to resolve calls to the new form of initialize(to:).

---

Mangled names

test/SILGen/borrow_from_load_expr.swift

UnsafeMutablePointer.subscript.unsafeAddressor name mangling changes

---

Documenting Escapable requirements

test/SourceKit/DocSupport/doc_clang_module.swift

Need to add Escapable as a conformance:

@@ -6203,6 +6203,11 @@
         key.kind: source.lang.swift.ref.protocol,
         key.name: "Copyable",
         key.usr: "s:s8CopyableP"
+      },
+      {
+        key.kind: source.lang.swift.ref.protocol,
+        key.name: "Escapable",
+        key.usr: "s:s9EscapableP"
       }

---

API signature changes

test/api-digester/stability-stdlib-source.swift

Accessor UnsafeMutablePointer.hashValue.Get() has generic signature change from to <Pointee where Pointee : ~Copyable, Pointee : ~Escapable>
etc...

[atrick]

@swift-ci test

[atrick]

@swift-ci test

[atrick]

@swift-ci benchmark

[atrick]

@swift-ci Please Build Toolchain macOS Platform