[lldb] Add summary formatter for TaskPriority (#10205)

Add a summary formatter for `TaskPriority` to print values with the names of the constants. See https://developer.apple.com/documentation/swift/taskpriority

Some values have more than one name, ex `high` and `userInitiated` are the same value. The [definition of `TaskPriority`](https://github.com/swiftlang/swift/blob/28f96411c9a1fe9c8768ac48c24a6974973876ff/stdlib/public/Concurrency/Task.swift#L308-L331) defines some some constants in terms of others. This summary formatter uses the seemingly "primary" names. As a result, if a user expects to see `userInitiated`, they will see `high` instead. Similarly, they'll see `low` instead of `utility`, and `medium` instead of `default`.

Author: kastiglione

lldb/source/Plugins/Language/Swift/SwiftFormatters.cpp

@@ -1605,6 +1605,38 @@ bool lldb_private::formatters::swift::TypePreservingNSNumber_SummaryProvider(
   return false;
 }
 
+bool lldb_private::formatters::swift::TaskPriority_SummaryProvider(
+    ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
+  uint64_t raw_value = UINT8_MAX;
+  if (auto child_sp = valobj.GetChildMemberWithName("rawValue"))
+    if (auto synthetic_sp = child_sp->GetSyntheticValue())
+      raw_value = synthetic_sp->GetValueAsUnsigned(UINT8_MAX);
+  if (raw_value >= UINT8_MAX)
+    return false;
+
+  switch (raw_value) {
+  case 0x19:
+    // Also .userInitiated
+    stream.PutCString(".high");
+    break;
+  case 0x15:
+    // Also .default (deprecated)
+    stream.PutCString(".medium");
+    break;
+  case 0x11:
+    // Also .utilitiy
+    stream.PutCString(".low");
+    break;
+  case 0x09:
+    stream.PutCString(".background");
+    break;
+  default:
+    stream.Format("{0}", raw_value);
+    break;
+  }
+  return true;
+}
+
 namespace {
 
 /// Enumerate the kinds of SIMD elements.

lldb/source/Plugins/Language/Swift/SwiftFormatters.h

@@ -114,6 +114,9 @@ bool ObjC_Selector_SummaryProvider(ValueObject &valobj, Stream &stream,
 bool TypePreservingNSNumber_SummaryProvider(ValueObject &valobj, Stream &stream,
                                             const TypeSummaryOptions &options);
 
+bool TaskPriority_SummaryProvider(ValueObject &valobj, Stream &stream,
+                                  const TypeSummaryOptions &options);
+
 SyntheticChildrenFrontEnd *EnumSyntheticFrontEndCreator(CXXSyntheticChildren *,
                                                         lldb::ValueObjectSP);
 

lldb/source/Plugins/Language/Swift/SwiftLanguage.cpp

@@ -482,6 +482,10 @@ static void LoadSwiftFormatters(lldb::TypeCategoryImplSP swift_category_sp) {
   AddCXXSummary(swift_category_sp, staticstring_summary_provider,
                 "Swift.StaticString summary provider",
                 ConstString("Swift.StaticString"), summary_flags);
+  AddCXXSummary(swift_category_sp,
+                lldb_private::formatters::swift::TaskPriority_SummaryProvider,
+                "Swift TaskPriority summary provider", "Swift.TaskPriority",
+                summary_flags);
   summary_flags.SetSkipPointers(false);
   // this is an ObjC dynamic type - as such it comes in pointer form
   // NSContiguousString* - do not skip pointers here

lldb/test/API/lang/swift/async/formatters/taskpriority/Makefile

@@ -0,0 +1,3 @@
+SWIFT_SOURCES := main.swift
+SWIFTFLAGS_EXTRAS := -parse-as-library
+include Makefile.rules

lldb/test/API/lang/swift/async/formatters/taskpriority/TestSwiftTaskPrioritySummary.py

@@ -0,0 +1,25 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestCase(TestBase):
+
+    @swiftTest
+    def test(self):
+        """Test summary formatter for TaskPriority."""
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "break here", lldb.SBFileSpec("main.swift")
+        )
+        self.expect(
+            "frame var",
+            substrs=[
+                "high = .high",
+                "medium = .medium",
+                "low = .low",
+                "background = .background",
+                "custom = 15",
+            ],
+        )

lldb/test/API/lang/swift/async/formatters/taskpriority/main.swift

@@ -0,0 +1,10 @@
+@main struct Entry {
+  static func main() {
+    let high = TaskPriority.high
+    let medium = TaskPriority.medium
+    let low = TaskPriority.low
+    let background = TaskPriority.background
+    let custom = TaskPriority(rawValue: 15)
+    print("break here")
+  }
+}