Merge pull request #8546 from apple/dl/lldb-Support-breakpoints-on-specific-property-accessor-blocks

[lldb] Support breakpoints on specific property accessor blocks

Author: adrian-prantl

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

@@ -138,6 +138,25 @@ SwiftLanguage::GetMethodNameVariants(ConstString method_name) const {
   if (method_name.GetMangledCounterpart(counterpart))
     if (SwiftLanguageRuntime::IsSwiftMangledName(counterpart.GetStringRef()))
       variant_names.emplace_back(counterpart, eFunctionNameTypeFull);
+
+  // Properties can have multiple accessor blocks. This section of code supports
+  // breakpoints on accessor blocks by name.
+  //
+  // By default, the name `A.B` is treated as a fully qualified name, where `B`
+  // is the basename. However, some names can be interpreted in two ways, for
+  // example `A.get`. First, it can refer to the name `get` (in module `A`, or
+  // in type `A`). Second, it can refer the *getter* block for property `A`.
+  // LLDB's baseline behavior handles the first case. The second case is
+  // produced here as a variant name.
+  for (StringRef suffix : {".get", ".set", ".willset", ".didset"})
+    if (method_name.GetStringRef().ends_with(suffix)) {
+      // The method name, complete with suffix, *is* the variant.
+      variant_names.emplace_back(method_name, eFunctionNameTypeFull |
+                                                  eFunctionNameTypeBase |
+                                                  eFunctionNameTypeMethod);
+      break;
+    }
+
   return variant_names;
 }
 

lldb/test/API/functionalities/breakpoint/swift_property_accessors/Makefile

@@ -0,0 +1,4 @@
+
+SWIFT_SOURCES := main.swift
+
+include Makefile.rules

lldb/test/API/functionalities/breakpoint/swift_property_accessors/TestSwiftPropertyAccessorBreakpoints.py

@@ -0,0 +1,28 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+
+
+class TestCase(TestBase):
+    @swiftTest
+    def test(self):
+        """Test that a breakpoint on a property accessor can be set by name."""
+        self.build()
+        exe = self.getBuildArtifact("a.out")
+        target = self.dbg.CreateTarget(exe)
+        for name in (
+            "read_only.get",
+            "read_write.get",
+            "read_write.set",
+            "observed.willset",
+            "observed.didset",
+        ):
+            bp = target.BreakpointCreateByName(name, "a.out")
+            self.assertEqual(bp.num_locations, 1, f"{name} breakpoint failed")
+
+        # Setting a breakpoint on the name "get" should not create a breakpoint
+        # matching property getters. The other accerssor suffixes should also
+        # not succeed as bare names.
+        for name in ("get", "set", "willset", "didset"):
+            bp = target.BreakpointCreateByName(name, "a.out")
+            self.assertEqual(bp.num_locations, 0, f"{name} breakpoint unexpected")

lldb/test/API/functionalities/breakpoint/swift_property_accessors/main.swift

@@ -0,0 +1,13 @@
+struct Thing {
+    var read_only: Int { 22 + 15 }
+
+    var read_write: Int {
+        get { 23 + 41 }
+        set { print("nothing") }
+    }
+
+    var observed: Int {
+        willSet { print("willSet") }
+        didSet { print("didSet") }
+    }
+}