[lldb] Turn on OSC 9;4 graphical progress in supported terminals

[JDevlieghere]

In #162162, I added support for OSC 9;4 graphical progress. I put it behind the show-progress setting because I didn't have a reliable way to detect whether the escape code was supported by the terminal.

Since then, more tools have added support for it, most notably Claude Code and Homebrew. While I still don't have a good way to detect this, there are a handful of known terminals that are easy enough to identify.

This PR toggles the default of show-progress to on again and puts showing the progress behind a check for those known terminals (Windows Terminal, ConEmu & Ghostty).

This means that if you're running in one of those, you'll get the visual progress by default unless you set show-progress to off. The downside is that if you're on an unrecognized terminal, you can't force it on any longer by setting show-progress to on. I think that's a fair trade-off as the setting wasn't really advertised and I doubt many people are using that. As a workaround, they can set OSC_PROGRESS to spoof an OSC-supporting terminal.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Jonas Devlieghere (JDevlieghere)

Changes

In #162162, I added support for OSC 9;4 graphical progress. I put it behind the show-progress setting because I didn't have a reliable way to detect whether the escape code was supported by the terminal.

Since then, more tools have added support for it, most notably Claude Code and Homebrew. While I still don't have a good way to detect this, there are a handful of known terminals that are easy enough to identify.

This PR toggles the default of show-progress to on again and puts showing the progress behind a check for those known terminals (Windows Terminal, ConEmu & Ghostty).

This means that if you're running in one of those, you'll get the visual progress by default unless you set show-progress to off. The downside is that if you're on an unrecognized terminal, you can't force it on any longer by setting show-progress to on. I think that's a fair trade-off as the setting wasn't really advertised and I doubt many people are using that. As a workaround, they can set OSC_PROGRESS to spoof an OSC-supporting terminal.

---

Full diff: https://github.com/llvm/llvm-project/pull/185541.diff

2 Files Affected:

• (modified) lldb/source/Core/CoreProperties.td (+1-1)
• (modified) lldb/source/Core/Debugger.cpp (+26-1)

diff --git a/lldb/source/Core/CoreProperties.td b/lldb/source/Core/CoreProperties.td
index c9141959a50f2..03326b130e067 100644
--- a/lldb/source/Core/CoreProperties.td
+++ b/lldb/source/Core/CoreProperties.td
@@ -184,7 +184,7 @@ let Definition = "debugger", Path = "" in {
   def ShowProgress
       : Property<"show-progress", "Boolean">,
         Global,
-        DefaultFalse,
+        DefaultTrue,
         Desc<"Whether to show progress using Operating System Command (OSC) "
              "Sequences in supporting terminal emulators.">;
   def ShowProgressAnsiPrefix: Property<"show-progress-ansi-prefix", "String">,
diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
index 05c2ed13374ae..a993e17162f73 100644
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -2077,6 +2077,30 @@ void Debugger::CancelForwardEvents(const ListenerSP &listener_sp) {
   m_forward_listener_sp.reset();
 }
 
+/// Conservative heuristic to detect whether OSC 9;4 progress is supported by
+/// the current terminal.
+static bool TerminalSupportsOSCProgress() {
+  static std::once_flag g_once_flag;
+  static bool g_supports_osc_progress = false;
+
+  std::call_once(g_once_flag, []() {
+    std::array<const char *, 4> g_known_env_vars = {
+        "WT_SESSION",            // Windows Terminal
+        "ConEmuPID",             // ConEmu
+        "GHOSTTY_RESOURCES_DIR", // Ghostty
+        "OSC_PROGRESS",          // Override
+    };
+    for (const char *env_var : g_known_env_vars) {
+      if (std::getenv(env_var)) {
+        g_supports_osc_progress = true;
+        return;
+      }
+    }
+  });
+
+  return g_supports_osc_progress;
+}
+
 bool Debugger::IsEscapeCodeCapableTTY() {
   if (lldb::LockableStreamFileSP stream_sp = GetOutputStreamSP()) {
     File &file = stream_sp->GetUnlockedFile();
@@ -2305,7 +2329,8 @@ void Debugger::HandleProgressEvent(const lldb::EventSP &event_sp) {
     }
 
     // Show progress using Operating System Command (OSC) sequences.
-    if (GetShowProgress() && IsEscapeCodeCapableTTY()) {
+    if (GetShowProgress() && IsEscapeCodeCapableTTY() &&
+        TerminalSupportsOSCProgress()) {
       if (lldb::LockableStreamFileSP stream_sp = GetOutputStreamSP()) {
 
         // Clear progress if this was the last progress event.