[Lldb-commits] [PATCH] D100977: [lldb] Use forward type in pointer-to-member

[Raphael Isemann via Phabricator via lldb-commits]

teemperor accepted this revision.
teemperor added a comment.
This revision is now accepted and ready to land.

The test below reproduces the eager layout generation (and the resulting crashes) for me. Just apply it on top and then this is good to go. Thanks for tracking this down!

  diff --git a/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/Makefile b/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/Makefile
  new file mode 100644
  index 000000000000..99998b20bcb0
  --- /dev/null
  +++ b/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/Makefile
  @@ -0,0 +1,3 @@
  +CXX_SOURCES := main.cpp
  +
  +include Makefile.rules
  diff --git a/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/TestPointerToMemberTypeDependingOnParentSize.py b/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/TestPointerToMemberTypeDependingOnParentSize.py
  new file mode 100644
  index 000000000000..fd978158e716
  --- /dev/null
  +++ b/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/TestPointerToMemberTypeDependingOnParentSize.py
  @@ -0,0 +1,24 @@
  +import lldb
  +from lldbsuite.test.decorators import *
  +from lldbsuite.test.lldbtest import *
  +from lldbsuite.test import lldbutil
  +
  +class TestCase(TestBase):
  +
  +    mydir = TestBase.compute_mydir(__file__)
  +
  +    @no_debug_info_test
  +    def test(self):
  +        """
  +        This tests a pointer-to-member member which class part is the
  +        surrounding class. LLDB should *not* try to generate the record layout
  +        of the class when parsing pointer-to-member types while parsing debug
  +        info (as the references class might not be complete when the type is
  +        parsed).
  +        """
  +        self.build()
  +        self.dbg.CreateTarget(self.getBuildArtifact("a.out"))
  +
  +        # Force the record layout for 'ToLayout' to be generated by printing
  +        # a value of it's type.
  +        self.expect("target variable test_var")
  diff --git a/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/main.cpp b/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/main.cpp
  new file mode 100644
  index 000000000000..4787691ac9f7
  --- /dev/null
  +++ b/lldb/test/API/lang/cpp/pointer_to_member_type_depending_on_parent_size/main.cpp
  @@ -0,0 +1,35 @@
  +// This class just serves as an indirection between LLDB and Clang. LLDB might
  +// be tempted to check the member type of DependsOnParam2 for whether it's
  +// in some 'currently-loading' state before trying to produce the record layout.
  +// By inheriting from ToLayout this will make LLDB just check if
  +// DependsOnParam1 is currently being loaded (which it's not) but it won't
  +// check if all the types DependsOnParam2 is depending on for its layout are
  +// currently parsed.
  +template <typename ToLayoutParam> struct DependsOnParam1 : ToLayoutParam {};
  +// This class forces the memory layout of it's type parameter to be created.
  +template <typename ToLayoutParam> struct DependsOnParam2 {
  +  DependsOnParam1<ToLayoutParam> m;
  +};
  +
  +// This is the class that LLDB has to generate the record layout for.
  +struct ToLayout {
  +  // The class part of this pointer-to-member type has a memory layout that
  +  // depends on the surrounding class. If LLDB eagerly tries to layout the
  +  // class part of a pointer-to-member type while parsing, then layouting this
  +  // type should cause a test failure (as we aren't done parsing ToLayout
  +  // at this point).
  +  int DependsOnParam2<ToLayout>::* pointer_to_member_member;
  +  // Some dummy member variable. This is only there so that Clang can detect
  +  // that the record layout is inconsistent (i.e., the number of fields in the
  +  // layout doesn't fit to the fields in the declaration).
  +  int some_member;
  +};
  +
  +// Emit the definition of DependsOnParam2<ToLayout>. It seems Clang won't
  +// emit the definition of a class template if it's only used in the class part
  +// of a pointer-to-member type.
  +DependsOnParam2<ToLayout> x;
  +
  +ToLayout test_var;
  +
  +int main() { return test_var.some_member; }


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  https://reviews.llvm.org/D100977/new/

https://reviews.llvm.org/D100977