Merge branch 'master' into fix/SR-10492

Author: theblixguy

cmake/modules/SwiftSource.cmake

@@ -229,6 +229,7 @@ function(_compile_swift_files
   # The standard library and overlays are always built resiliently.
   if(SWIFTFILE_IS_STDLIB)
     list(APPEND swift_flags "-enable-library-evolution")
+    list(APPEND swift_flags "-Xfrontend" "-enable-ownership-stripping-after-serialization")
   endif()
 
   if(SWIFT_STDLIB_USE_NONATOMIC_RC)

docs/Diagnostics.md

@@ -97,7 +97,7 @@ Most diagnostics have no reason to change behavior under editor mode. An example
 
 - `%0`, `%1`, etc - Formats the specified diagnostic argument based on its type.
 
-- `%select{a|b|c}0` - Chooses from a list of alternatives, separated by vertical bars, based on the value of the given argument. In this example, a value of 2 in diagnostic argument 0 would result in "c" being output.
+- `%select{a|b|c}0` - Chooses from a list of alternatives, separated by vertical bars, based on the value of the given argument. In this example, a value of 2 in diagnostic argument 0 would result in "c" being output. The argument to the %select may be an integer, enum, or StringRef. If it's a StringRef, the specifier acts as an emptiness check.
 
 - `%s0` - Produces an "s" if the given argument is anything other than 1, as meant for an English plural. This isn't particularly localizable without a more general `%plural` form, but most diagnostics try to avoid cases where a plural/singular distinction would be necessary in the first place.
 

docs/SIL.rst

@@ -2802,6 +2802,21 @@ It is expected that the strong reference count of the object is one.
 Furthermore, no other thread may increment the strong reference count during
 execution of this instruction.
 
+copy_unowned_value
+``````````````````
+::
+
+  sil-instruction ::= 'copy_unowned_value' sil-operand
+
+  %1 = copy_unowned_value %0 : $@unowned T
+  // %1 will be a strong @owned value of type $T.
+  // $T must be a reference type
+
+Asserts that the strong reference count of the heap object referenced by ``%0``
+is still positive, then increments the reference count and returns a new strong
+reference to ``%0``. The intention is that this instruction is used as a "safe
+ownership conversion" from ``unowned`` to ``strong``.
+
 strong_retain_unowned
 `````````````````````
 ::
@@ -3712,6 +3727,21 @@ This instruction has the same local semantics as ``retain_value`` but:
 The intention is that this instruction is used to implement unmanaged
 constructs.
 
+copy_unmanaged_value
+``````````````````````
+
+::
+
+  sil-instruction ::= 'copy_unmanaged_value' sil-value
+
+  %1 = copy_unmanaged_value %0 : $@sil_unmanaged A
+  // %1 will be a strong @owned $A.
+
+This instruction has the same semantics as ``copy_value`` except that its input
+is a trivial ``@sil_unmanaged`` type that doesn't require ref counting. This is
+intended to be used semantically as a "conversion" like instruction from
+``unmanaged`` to ``strong`` and thus should never be removed by the optimizer.
+
 copy_value
 ``````````