[lldb] Support "dereferencing" std::optional in frame var

[labath]

No description provided.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Pavel Labath (labath)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/107077.diff

3 Files Affected:

• (modified) lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp (+2)
• (modified) lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/TestDataFormatterGenericOptional.py (+12)
• (modified) lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/main.cpp (+5)

diff --git a/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp b/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp
index 23756de7f1e66e..a8a7c16de5e867 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp
@@ -37,6 +37,8 @@ class GenericOptionalFrontend : public SyntheticChildrenFrontEnd {
   GenericOptionalFrontend(ValueObject &valobj, StdLib stdlib);
 
   size_t GetIndexOfChildWithName(ConstString name) override {
+    if (name == "$$dereference$$")
+      return 0;
     return formatters::ExtractIndexFromString(name.GetCString());
   }
 
diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/TestDataFormatterGenericOptional.py b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/TestDataFormatterGenericOptional.py
index f6507294bfb2ac..7dc656a7ae225c 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/TestDataFormatterGenericOptional.py
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/TestDataFormatterGenericOptional.py
@@ -79,6 +79,18 @@ def cleanup():
             ],
         )
 
+        self.expect_var_path("*number_engaged", value="42")
+        self.expect_var_path("*x", children=[ValueCheck(name="x", value="42")])
+        self.expect_var_path("x->x", value="42")
+
+        # The error message could use some improvement, but at least we can
+        # check we don't crash.
+        self.expect(
+            "frame variable *number_not_engaged",
+            error=True,
+            substrs=["not a pointer or reference type"],
+        )
+
     @add_test_categories(["libc++"])
     ## Clang 7.0 is the oldest Clang that can reliably parse newer libc++ versions
     ## with -std=c++17.
diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/main.cpp b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/main.cpp
index 8f30df4626636c..18a95b9cc246c6 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/main.cpp
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/main.cpp
@@ -12,6 +12,10 @@
 #define HAVE_OPTIONAL 0
 #endif
 
+struct X {
+  int x;
+};
+
 int main() {
   bool has_optional = HAVE_OPTIONAL;
 
@@ -25,6 +29,7 @@ int main() {
 
   optional_int number_not_engaged;
   optional_int number_engaged = 42;
+  std::optional<X> x = X{42};
 
   printf("%d\n", *number_engaged);
 

[Michael137]

Nice, was wishing for this just yesterday

[Michael137]

Yea would be nice to bubble a nicer error up somehow. Looks like ValueObject currently just drops any error set by the dereferenced ValueObject (we don't set one in the formatter currently anyway). But not urgent