[LLDB] Run MSVC variant test with PDB

[Nerixyz]

Split off from #171489. This only adds the lookup of the active type for a std::variant based on the head type (since PDB doesn't have template info).

[Michael137]

Do we need a nullcheck on head here?

[Michael137]

LGTM (module comment)

[llvmbot]

@llvm/pr-subscribers-lldb

Author: nerix (Nerixyz)

Changes

Split off from #171489. This only adds the lookup of the active type for a std::variant based on the head type (since PDB doesn't have template info).

---

Full diff: https://github.com/llvm/llvm-project/pull/171858.diff

2 Files Affected:

• (modified) lldb/source/Plugins/Language/CPlusPlus/MsvcStlVariant.cpp (+10-2)
• (modified) lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/variant/TestDataFormatterStdVariant.py (+2)

diff --git a/lldb/source/Plugins/Language/CPlusPlus/MsvcStlVariant.cpp b/lldb/source/Plugins/Language/CPlusPlus/MsvcStlVariant.cpp
index 52a3d98d2af4b..3e7647be48bb0 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/MsvcStlVariant.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/MsvcStlVariant.cpp
@@ -119,8 +119,16 @@ bool formatters::MsvcStlVariantSummaryProvider(
     storage_type = storage_type.GetTypedefedType();
 
   CompilerType active_type = storage_type.GetTypeTemplateArgument(1, true);
-  if (!active_type)
-    return false;
+  if (!active_type) {
+    // PDB: get the type from the head as we don't have template arguments
+    // there.
+    ValueObjectSP head = GetHead(*storage);
+    if (!head)
+      return false;
+    active_type = head->GetCompilerType();
+    if (!active_type)
+      return false;
+  }
 
   stream << " Active Type = " << active_type.GetDisplayTypeName() << " ";
   return true;
diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/variant/TestDataFormatterStdVariant.py b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/variant/TestDataFormatterStdVariant.py
index 9f32ad97c1f0a..1ae07a91dfe3d 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/variant/TestDataFormatterStdVariant.py
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/variant/TestDataFormatterStdVariant.py
@@ -9,6 +9,8 @@
 
 
 class StdVariantDataFormatterTestCase(TestBase):
+    TEST_WITH_PDB_DEBUG_INFO = True
+
     def do_test(self):
         """Test that that file and class static variables display correctly."""