[Lldb-commits] [PATCH] D143068: [lldb][SymbolFileDWARF] Support by-name lookup of global variables in inline namespaces

[Michael Buch via Phabricator via lldb-commits]

Michael137 created this revision.
Michael137 added reviewers: aprantl, labath, jingham.
Herald added a project: All.
Michael137 requested review of this revision.
Herald added a project: LLDB.
Herald added a subscriber: lldb-commits.

Currently evaluating an expression involving a global variable inside
an inline namespace will fail to lookup said variable. This is because
the `SymbolFileDWARF::FindGlobalVariables` discards from consideration
all DIEs whose decl_context doesn't exactly match that of the lookup.

This patch relaxes this restriction by checking whether C++ rules
would permit the lookup.

The motivation for this is evaluating `std::ranges` expressions, which
heavily rely on global variables inside inline namespaces. E.g.,
`std::views::all(...)` is just an invocation of the `operator()`
on `std::ranges::views::__cpo::all`.

**Testing**

- Added API tests


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D143068

Files:
  lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
  lldb/test/API/commands/expression/inline-namespace/TestInlineNamespace.py
  lldb/test/API/commands/expression/inline-namespace/main.cpp


Index: lldb/test/API/commands/expression/inline-namespace/main.cpp
===================================================================
--- lldb/test/API/commands/expression/inline-namespace/main.cpp
+++ lldb/test/API/commands/expression/inline-namespace/main.cpp
@@ -1,10 +1,23 @@
 namespace A {
   inline namespace B {
     int f() { return 3; }
+    int global_var = 0;
+
+    namespace C {
+    int global_var = 1;
+    }
   };
+
+  namespace D {
+  inline namespace F {
+  int other_var = 2;
+  }
+  } // namespace D
+
+  int global_var = 3;
 }
 
 int main(int argc, char **argv) {
   // Set break point at this line.
-  return A::f();
+  return A::f() + A::B::global_var + A::C::global_var + A::D::F::other_var;
 }
Index: lldb/test/API/commands/expression/inline-namespace/TestInlineNamespace.py
===================================================================
--- lldb/test/API/commands/expression/inline-namespace/TestInlineNamespace.py
+++ lldb/test/API/commands/expression/inline-namespace/TestInlineNamespace.py
@@ -23,3 +23,30 @@
         # But we should still find the function when we pretend the inline
         # namespace is not inline.
         self.expect_expr("A::B::f()", result_type="int", result_value="3")
+
+        self.expect_expr("A::B::global_var", result_type="int", result_value="0")
+        # FIXME: should be ambiguous lookup but ClangExpressionDeclMap takes
+        #        first global variable that the lookup found, which in this case
+        #        is A::B::global_var
+        self.expect_expr("A::global_var", result_type="int", result_value="0")
+
+        self.expect_expr("A::B::C::global_var", result_type="int", result_value="1")
+        self.expect_expr("A::C::global_var", result_type="int", result_value="1")
+
+        self.expect_expr("A::D::F::other_var", result_type="int", result_value="2")
+        self.expect_expr("A::D::other_var", result_type="int", result_value="2")
+
+        self.expect("expr A::D::global_var", error=True, substrs=["no member named 'global_var' in namespace 'A::D'"])
+        self.expect("expr A::D::F::global_var", error=True, substrs=["no member named 'global_var' in namespace 'A::D::F'"])
+
+        self.expect("expr A::other_var", error=True, substrs=["no member named 'other_var' in namespace 'A'"])
+        self.expect("expr A::B::other_var", error=True, substrs=["no member named 'other_var' in namespace 'A::B'"])
+        self.expect("expr B::other_var", error=True, substrs=["no member named 'other_var' in namespace 'A::B'"])
+
+        # 'frame variable' can correctly distinguish between A::B::global_var and A::global_var
+        gvars = self.target().FindGlobalVariables("A::global_var", 10)
+        self.assertEqual(len(gvars), 1)
+        self.assertEqual(gvars[0].GetValueAsSigned(), 3)
+
+        self.expect("frame variable A::global_var", substrs=["(int) A::global_var = 3"])
+        self.expect("frame variable A::B::global_var", substrs=["(int) A::B::global_var = 0"])
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -2223,7 +2223,8 @@
         CompilerDeclContext actual_parent_decl_ctx =
             dwarf_ast->GetDeclContextContainingUIDFromDWARF(die);
         if (!actual_parent_decl_ctx ||
-            actual_parent_decl_ctx != parent_decl_ctx)
+            (actual_parent_decl_ctx != parent_decl_ctx
+             && !parent_decl_ctx.IsContainedInLookup(actual_parent_decl_ctx)))
           return true;
       }
     }


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