[lldb] add a marker before skipped frames

lldb/include/lldb/Target/StackFrame.h

@@ -363,7 +363,7 @@ class StackFrame : public ExecutionContextScope,
   /// \param [in] frame_marker
   ///   Optional string that will be prepended to the frame output description.
   virtual void DumpUsingSettingsFormat(Stream *strm, bool show_unique = false,
-                                       const char *frame_marker = nullptr);
+                                       const llvm::StringRef frame_marker = "");
 
   /// Print a description for this frame using a default format.
   ///
@@ -400,7 +400,7 @@ class StackFrame : public ExecutionContextScope,
   ///   Returns true if successful.
   virtual bool GetStatus(Stream &strm, bool show_frame_info, bool show_source,
                          bool show_unique = false,
-                         const char *frame_marker = nullptr);
+                         const llvm::StringRef frame_marker = "");
 
   /// Query whether this frame is a concrete frame on the call stack, or if it
   /// is an inlined frame derived from the debug information and presented by

lldb/include/lldb/Target/StackFrameList.h

@@ -49,6 +49,22 @@ class StackFrameList : public std::enable_shared_from_this<StackFrameList> {
   /// Resets the selected frame index of this object.
   void ClearSelectedFrameIndex();
 
+  /// Returns \p true if the next frame is hidden.
+  bool IsNextFrameHidden(lldb_private::StackFrame &frame);
+
+  /// Returns \p true if the previous frame is hidden.
+  bool IsPreviousFrameHidden(lldb_private::StackFrame &frame);
+
+  /// Returns the stack frame marker depending on if \p frame_sp:
+  /// @li is selected: *
+  /// @li is the first non hidden frame: ﹍
+  /// @li is the last non hidden frame: ﹉
+  ///
+  /// If the terminal does not support Unicode rendering, the hidden frame
+  /// markers are replaced with whitespaces.
+  std::wstring FrameMarker(lldb::StackFrameSP frame_sp,
+                           lldb::StackFrameSP selected_frame_sp);
+
   /// Get the currently selected frame index.
   /// We should only call SelectMostRelevantFrame if (a) the user hasn't already
   /// selected a frame, and (b) if this really is a user facing
@@ -96,7 +112,7 @@ class StackFrameList : public std::enable_shared_from_this<StackFrameList> {
   size_t GetStatus(Stream &strm, uint32_t first_frame, uint32_t num_frames,
                    bool show_frame_info, uint32_t num_frames_with_source,
                    bool show_unique = false, bool show_hidden = false,
-                   const char *frame_marker = nullptr);
+                   bool show_selected_frame = false);
 
   /// Returns whether we have currently fetched all the frames of a stack.
   bool WereAllFramesFetched() const;

lldb/packages/Python/lldbsuite/test/decorators.py

@@ -438,6 +438,35 @@ def impl(func):
     return impl
 
 
+def unicode_test(func):
+    """Decorate the item as a test which requires Unicode to be enabled.
+
+    lldb checks the value of the `LANG` environment variable for the substring "utf-8"
+    to determine if the terminal supports Unicode (except on Windows, were we assume
+    it's always supported).
+    This decorator sets LANG to `utf-8` before running the test and resets it to its
+    previous value afterwards.
+    """
+
+    def unicode_wrapped(*args, **kwargs):
+        import os
+
+        previous_lang = os.environ.get("LANG", None)
+        os.environ["LANG"] = "en_US.UTF-8"
+        try:
+            func(*args, **kwargs)
+        except Exception as err:
+            raise err
+        finally:
+            # Reset the value, whether the test failed or not.
+            if previous_lang is not None:
+                os.environ["LANG"] = previous_lang
+            else:
+                del os.environ["LANG"]
+
+    return unicode_wrapped
+
+
 def no_debug_info_test(func):
     """Decorate the item as a test what don't use any debug info. If this annotation is specified
     then the test runner won't generate a separate test for each debug info format."""

lldb/source/Target/StackFrame.cpp

@@ -1945,7 +1945,7 @@ bool StackFrame::DumpUsingFormat(Stream &strm,
 }
 
 void StackFrame::DumpUsingSettingsFormat(Stream *strm, bool show_unique,
-                                         const char *frame_marker) {
+                                         const llvm::StringRef frame_marker) {
   if (strm == nullptr)
     return;
 
@@ -2044,7 +2044,8 @@ bool StackFrame::HasCachedData() const {
 }
 
 bool StackFrame::GetStatus(Stream &strm, bool show_frame_info, bool show_source,
-                           bool show_unique, const char *frame_marker) {
+                           bool show_unique,
+                           const llvm::StringRef frame_marker) {
   if (show_frame_info) {
     strm.Indent();
     DumpUsingSettingsFormat(&strm, show_unique, frame_marker);

lldb/source/Target/StackFrameList.cpp

@@ -27,6 +27,7 @@
 #include "lldb/Utility/LLDBLog.h"
 #include "lldb/Utility/Log.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Support/ConvertUTF.h"
 
 #include <memory>
 
@@ -928,11 +929,42 @@ StackFrameList::GetStackFrameSPForStackFramePtr(StackFrame *stack_frame_ptr) {
   return ret_sp;
 }
 
+bool StackFrameList::IsNextFrameHidden(lldb_private::StackFrame &frame) {
+  uint32_t frame_idx = frame.GetFrameIndex();
+  StackFrameSP frame_sp = GetFrameAtIndex(frame_idx + 1);
+  if (!frame_sp)
+    return false;
+  return frame_sp->IsHidden();
+}
+
+bool StackFrameList::IsPreviousFrameHidden(lldb_private::StackFrame &frame) {
+  uint32_t frame_idx = frame.GetFrameIndex();
+  if (frame_idx == 0)
+    return false;
+  StackFrameSP frame_sp = GetFrameAtIndex(frame_idx - 1);
+  if (!frame_sp)
+    return false;
+  return frame_sp->IsHidden();
+}
+
+std::wstring StackFrameList::FrameMarker(lldb::StackFrameSP frame_sp,
+                                         lldb::StackFrameSP selected_frame_sp) {
+  if (frame_sp == selected_frame_sp)
+    return Terminal::SupportsUnicode() ? L" * " : L"* ";
+  else if (!Terminal::SupportsUnicode())
+    return L"  ";
+  else if (IsPreviousFrameHidden(*frame_sp))
+    return L"﹉ ";
+  else if (IsNextFrameHidden(*frame_sp))
+    return L"﹍ ";
+  return L"   ";
+}
+
 size_t StackFrameList::GetStatus(Stream &strm, uint32_t first_frame,
                                  uint32_t num_frames, bool show_frame_info,
                                  uint32_t num_frames_with_source,
                                  bool show_unique, bool show_hidden,
-                                 const char *selected_frame_marker) {
+                                 bool show_selected_frame) {
   size_t num_frames_displayed = 0;
 
   if (num_frames == 0)
@@ -950,25 +982,17 @@ size_t StackFrameList::GetStatus(Stream &strm, uint32_t first_frame,
 
   StackFrameSP selected_frame_sp =
       m_thread.GetSelectedFrame(DoNoSelectMostRelevantFrame);
-  const char *unselected_marker = nullptr;
   std::string buffer;
-  if (selected_frame_marker) {
-    size_t len = strlen(selected_frame_marker);
-    buffer.insert(buffer.begin(), len, ' ');
-    unselected_marker = buffer.c_str();
-  }
-  const char *marker = nullptr;
+  std::wstring marker;
   for (frame_idx = first_frame; frame_idx < last_frame; ++frame_idx) {
     frame_sp = GetFrameAtIndex(frame_idx);
     if (!frame_sp)
       break;
 
-    if (selected_frame_marker != nullptr) {
-      if (frame_sp == selected_frame_sp)
-        marker = selected_frame_marker;
-      else
-        marker = unselected_marker;
-    }
+    if (show_selected_frame)
+      marker = FrameMarker(frame_sp, selected_frame_sp);
+    else
+      marker = FrameMarker(frame_sp, nullptr);
 
     // Hide uninteresting frames unless it's the selected frame.
     if (!show_hidden && frame_sp != selected_frame_sp && frame_sp->IsHidden())
@@ -982,10 +1006,11 @@ size_t StackFrameList::GetStatus(Stream &strm, uint32_t first_frame,
             m_thread.GetID(), num_frames_displayed))
       break;
 
-
+    std::string marker_utf8;
+    llvm::convertWideToUTF8(marker, marker_utf8);
     if (!frame_sp->GetStatus(strm, show_frame_info,
                              num_frames_with_source > (first_frame - frame_idx),
-                             show_unique, marker))
+                             show_unique, marker_utf8))
       break;
     ++num_frames_displayed;
   }

lldb/source/Target/Thread.cpp

@@ -1887,16 +1887,16 @@ size_t Thread::GetStatus(Stream &strm, uint32_t start_frame,
 
     const bool show_frame_info = true;
     const bool show_frame_unique = only_stacks;
-    const char *selected_frame_marker = nullptr;
+    bool show_selected_frame = false;
     if (num_frames == 1 || only_stacks ||
         (GetID() != GetProcess()->GetThreadList().GetSelectedThread()->GetID()))
       strm.IndentMore();
     else
-      selected_frame_marker = "* ";
+      show_selected_frame = true;
 
     num_frames_shown = GetStackFrameList()->GetStatus(
         strm, start_frame, num_frames, show_frame_info, num_frames_with_source,
-        show_frame_unique, show_hidden, selected_frame_marker);
+        show_frame_unique, show_hidden, show_selected_frame);
     if (num_frames == 1)
       strm.IndentLess();
     strm.IndentLess();

lldb/test/API/terminal/hidden_frame_markers/Makefile

@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

lldb/test/API/terminal/hidden_frame_markers/TestHiddenFrameMarkers.py

@@ -0,0 +1,52 @@
+"""
+Test that hidden frames are delimited with markers.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class HiddenFrameMarkerTest(TestBase):
+    @unicode_test
+    def test_hidden_frame_markers(self):
+        """Test that hidden frame markers are rendered in backtraces"""
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "// break here", lldb.SBFileSpec("main.cpp")
+        )
+        self.expect(
+            "bt",
+            substrs=[
+                "   * frame #0:",
+                "  ﹍ frame #1:",
+                "  ﹉ frame #7:",
+                "     frame #8:",
+                "     frame #9:",
+            ],
+        )
+
+        self.runCmd("f 1")
+        self.expect(
+            "bt",
+            substrs=[
+                "     frame #0:",
+                "   * frame #1:",
+                "  ﹉ frame #7:",
+                "     frame #8:",
+                "     frame #9:",
+            ],
+        )
+
+        self.runCmd("f 7")
+        self.expect(
+            "bt",
+            substrs=[
+                "     frame #0:",
+                "  ﹍ frame #1:",
+                "   * frame #7:",
+                "     frame #8:",
+                "     frame #9:",
+            ],
+        )

lldb/test/API/terminal/hidden_frame_markers/main.cpp

@@ -0,0 +1,12 @@
+#include <functional>
+#include <iostream>
+
+static void target() {
+  int a = 0; // break here
+}
+
+int main() {
+  std::function<void()> fn = [] { target(); };
+  fn();
+  return 0;
+}