Revert "[lldb][DWARFASTParserClang] Fetch constant value from variable defintion if available (#71004)"

This reverts commit ef3feba.

This caused an LLDB test failure on Linux for `lang/cpp/symbols/TestSymbols.test_dwo`:

```
make: Leaving directory '/home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/lang/cpp/symbols/TestSymbols.test_dwo'
runCmd: expression -- D::i
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	HandleCommand(command = "expression -- D::i")
1.	<user expression 0>:1:4: current parser token 'i'
2.	<lldb wrapper prefix>:44:1: parsing function body '$__lldb_expr'
3.	<lldb wrapper prefix>:44:1: in compound statement ('{}')
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  _lldb.cpython-39-x86_64-linux-gnu.so 0x00007fbcfcb08b87
1  _lldb.cpython-39-x86_64-linux-gnu.so 0x00007fbcfcb067ae
2  _lldb.cpython-39-x86_64-linux-gnu.so 0x00007fbcfcb0923f
3  libpthread.so.0                      0x00007fbd07ab7140
```

And a failure in `TestCallStdStringFunction.py` on Linux aarch64:
```
--
Exit Code: -11

Command Output (stdout):
--
lldb version 18.0.0git (https://github.com/llvm/llvm-project.git revision ef3feba)
  clang revision ef3feba
  llvm revision ef3feba

--
Command Output (stderr):
--
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      HandleCommand(command = "expression str")
1.      <lldb wrapper prefix>:45:34: current parser token ';'
2.      <lldb wrapper prefix>:44:1: parsing function body '$__lldb_expr'
3.      <lldb wrapper prefix>:44:1: in compound statement ('{}')
  #0 0x0000ffffb72a149c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lib/python3.8/site-packages/lldb/_[lldb.cpython-38-aarch64-linux-gnu.so](http://lldb.cpython-38-aarch64-linux-gnu.so/)+0x58c749c)
  #1 0x0000ffffb729f458 llvm::sys::RunSignalHandlers() (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lib/python3.8/site-packages/lldb/_[lldb.cpython-38-aarch64-linux-gnu.so](http://lldb.cpython-38-aarch64-linux-gnu.so/)+0x58c5458)
  #2 0x0000ffffb72a1bd0 SignalHandler(int) (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lib/python3.8/site-packages/lldb/_[lldb.cpython-38-aarch64-linux-gnu.so](http://lldb.cpython-38-aarch64-linux-gnu.so/)+0x58c7bd0)
  #3 0x0000ffffbdd9e7dc (linux-vdso.so.1+0x7dc)
  #4 0x0000ffffb71799d8 lldb_private::plugin::dwarf::SymbolFileDWARF::FindGlobalVariables(lldb_private::ConstString, lldb_private::CompilerDeclContext const&, unsigned int, lldb_private::VariableList&) (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lib/python3.8/site-packages/lldb/_[lldb.cpython-38-aarch64-linux-gnu.so](http://lldb.cpython-38-aarch64-linux-gnu.so/)+0x579f9d8)
  #5 0x0000ffffb7197508 DWARFASTParserClang::FindConstantOnVariableDefinition(lldb_private::plugin::dwarf::DWARFDIE) (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lib/python3.8/site-packages/lldb/_[lldb.cpython-38-aarch64-linux-gnu.so](http://lldb.cpython-38-aarch64-linux-gnu.so/)+0x57bd508)
```

Author: Michael137

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

@@ -31,7 +31,6 @@
 #include "lldb/Symbol/SymbolFile.h"
 #include "lldb/Symbol/TypeList.h"
 #include "lldb/Symbol/TypeMap.h"
-#include "lldb/Symbol/VariableList.h"
 #include "lldb/Target/Language.h"
 #include "lldb/Utility/LLDBAssert.h"
 #include "lldb/Utility/Log.h"
@@ -134,54 +133,6 @@ static lldb::ModuleSP GetContainingClangModule(const DWARFDIE &die) {
   return lldb::ModuleSP();
 }
 
-std::optional<DWARFFormValue>
-DWARFASTParserClang::FindConstantOnVariableDefinition(DWARFDIE die) {
-  assert(die.Tag() == llvm::dwarf::DW_TAG_member);
-
-  auto *dwarf = die.GetDWARF();
-  if (!dwarf)
-    return {};
-
-  ConstString name{die.GetName()};
-  if (!name)
-    return {};
-
-  auto *CU = die.GetCU();
-  if (!CU)
-    return {};
-
-  DWARFASTParser *dwarf_ast = dwarf->GetDWARFParser(*CU);
-  auto parent_decl_ctx = dwarf_ast->GetDeclContextContainingUIDFromDWARF(die);
-
-  // Make sure we populate the GetDieToVariable cache.
-  VariableList variables;
-  dwarf->FindGlobalVariables(name, parent_decl_ctx, UINT_MAX, variables);
-
-  // The cache contains the variable definition whose DW_AT_specification
-  // points to our declaration DIE. Look up that definition using our
-  // declaration.
-  auto const &die_to_var = dwarf->GetDIEToVariable();
-  auto it = die_to_var.find(die.GetDIE());
-  if (it == die_to_var.end())
-    return {};
-
-  auto var_sp = it->getSecond();
-  assert(var_sp != nullptr);
-
-  if (!var_sp->GetLocationIsConstantValueData())
-    return {};
-
-  auto def = dwarf->GetDIE(var_sp->GetID());
-  auto def_attrs = def.GetAttributes();
-  DWARFFormValue form_value;
-  if (!def_attrs.ExtractFormValueAtIndex(
-          def_attrs.FindAttributeIndex(llvm::dwarf::DW_AT_const_value),
-          form_value))
-    return {};
-
-  return form_value;
-}
-
 TypeSP DWARFASTParserClang::ParseTypeFromClangModule(const SymbolContext &sc,
                                                      const DWARFDIE &die,
                                                      Log *log) {
@@ -2955,21 +2906,9 @@ void DWARFASTParserClang::ParseSingleMember(
 
       bool unused;
       // TODO: Support float/double static members as well.
-      if (!ct.IsIntegerOrEnumerationType(unused))
+      if (!attrs.const_value_form || !ct.IsIntegerOrEnumerationType(unused))
         return;
 
-      // Newer versions of Clang don't emit the DW_AT_const_value
-      // on the declaration of an inline static data member. Instead
-      // it's attached to the definition DIE. If that's the case,
-      // try and fetch it.
-      if (!attrs.const_value_form) {
-        auto maybe_form_value = FindConstantOnVariableDefinition(die);
-        if (!maybe_form_value)
-          return;
-
-        attrs.const_value_form = *maybe_form_value;
-      }
-
       llvm::Expected<llvm::APInt> const_value_or_err =
           ExtractIntFromFormValue(ct, *attrs.const_value_form);
       if (!const_value_or_err) {

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h

@@ -373,17 +373,6 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
                        lldb_private::CompilerType &class_clang_type,
                        const lldb::AccessType default_accesibility,
                        lldb_private::ClangASTImporter::LayoutInfo &layout_info);
-
-  /// Tries to find the definition DW_TAG_variable DIE of the the specified
-  /// DW_TAG_member 'die'. If such definition exists, returns the
-  /// DW_AT_const_value of that definition if available. Returns std::nullopt
-  /// otherwise.
-  ///
-  /// In newer versions of clang, DW_AT_const_value attributes are not attached
-  /// to the declaration of a inline static data-member anymore, but rather on
-  /// its definition. This function is used to locate said constant.
-  std::optional<lldb_private::plugin::dwarf::DWARFFormValue>
-  FindConstantOnVariableDefinition(lldb_private::plugin::dwarf::DWARFDIE die);
 };
 
 /// Parsed form of all attributes that are relevant for type reconstruction.

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h

@@ -343,11 +343,6 @@ class SymbolFileDWARF : public SymbolFileCommon {
     return m_forward_decl_compiler_type_to_die;
   }
 
-  typedef llvm::DenseMap<const DWARFDebugInfoEntry *, lldb::VariableSP>
-      DIEToVariableSP;
-
-  virtual DIEToVariableSP &GetDIEToVariable() { return m_die_to_variable_sp; }
-
   virtual UniqueDWARFASTTypeMap &GetUniqueDWARFASTTypeMap();
 
   bool ClassOrStructIsVirtual(const DWARFDIE &die);
@@ -367,6 +362,9 @@ class SymbolFileDWARF : public SymbolFileCommon {
   Type *ResolveTypeUID(const DIERef &die_ref);
 
 protected:
+  typedef llvm::DenseMap<const DWARFDebugInfoEntry *, lldb::VariableSP>
+      DIEToVariableSP;
+
   SymbolFileDWARF(const SymbolFileDWARF &) = delete;
   const SymbolFileDWARF &operator=(const SymbolFileDWARF &) = delete;
 
@@ -490,6 +488,8 @@ class SymbolFileDWARF : public SymbolFileCommon {
 
   void UpdateExternalModuleListIfNeeded();
 
+  virtual DIEToVariableSP &GetDIEToVariable() { return m_die_to_variable_sp; }
+
   void BuildCuTranslationTable();
   std::optional<uint32_t> GetDWARFUnitIndex(uint32_t cu_idx);
 

lldb/test/API/lang/cpp/const_static_integral_member/TestConstStaticIntegralMember.py

@@ -139,24 +139,3 @@ def test_class_with_only_constexpr_static(self):
         self.expect_expr(
             "ClassWithEnumAlias::enum_alias_alias", result_value="scoped_enum_case1"
         )
-
-    def test_shadowed_static_inline_members(self):
-        """Tests that the expression evaluator and SBAPI can both
-        correctly determine the requested inline static variable
-        in the presence of multiple variables of the same name."""
-
-        self.build()
-        lldbutil.run_to_name_breakpoint(self, "bar")
-
-        self.check_global_var("ns::Foo::mem", "const int", "10")
-
-        self.expect_expr("mem", result_value="10")
-        self.expect_expr("Foo::mem", result_value="10")
-        self.expect_expr("ns::Foo::mem", result_value="10")
-        self.expect_expr("::Foo::mem", result_value="-29")
-
-    @expectedFailureAll(bugnumber="target var doesn't honour global namespace")
-    def test_shadowed_static_inline_members_xfail(self):
-        self.build()
-        lldbutil.run_to_name_breakpoint(self, "bar")
-        self.check_global_var("::Foo::mem", "const int", "-29")

lldb/test/API/lang/cpp/const_static_integral_member/main.cpp

@@ -89,25 +89,6 @@ struct ClassWithEnumAlias {
       ScopedEnum::scoped_enum_case1;
 };
 
-namespace ns {
-struct Foo {
-  constexpr static int mem = 10;
-
-  void bar() { return; }
-};
-} // namespace ns
-
-struct Foo {
-  constexpr static int mem = -29;
-};
-
-int func() {
-  Foo f1;
-  ns::Foo f2;
-  f2.bar();
-  return ns::Foo::mem + Foo::mem;
-}
-
 int main() {
   A a;
 
@@ -143,7 +124,6 @@ int main() {
 
   auto enum_alias_val = ClassWithEnumAlias::enum_alias;
   auto enum_alias_alias_val = ClassWithEnumAlias::enum_alias_alias;
-  auto ret = func();
 
   return 0; // break here
 }