From 78449b6d980fc78d418f9b44d815781eda7587f7 Mon Sep 17 00:00:00 2001
From: kcbanner <kcbanner@gmail.com>
Date: Wed, 26 Jul 2023 22:10:22 -0400
Subject: [PATCH] debug: skip unwind error printing on platforms that don't
 have_ucontext

---
 lib/std/debug.zig | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index 05657a2fbf..ddd0f0ec95 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -242,8 +242,7 @@ pub fn dumpStackTraceFromBase(context: *const ThreadContext) void {
         printSourceAtAddress(debug_info, stderr, it.unwind_state.?.dwarf_context.pc, tty_config) catch return;
 
         while (it.next()) |return_address| {
-            if (it.getLastError()) |unwind_error|
-                printUnwindError(debug_info, stderr, unwind_error.address, unwind_error.err, tty_config) catch {};
+            printLastUnwindError(&it, debug_info, stderr, tty_config);
 
             // On arm64 macOS, the address of the last frame is 0x0 rather than 0x1 as on x86_64 macOS,
             // therefore, we do a check for `return_address == 0` before subtracting 1 from it to avoid
@@ -252,10 +251,7 @@ pub fn dumpStackTraceFromBase(context: *const ThreadContext) void {
             // same behaviour for x86-windows-msvc
             const address = if (return_address == 0) return_address else return_address - 1;
             printSourceAtAddress(debug_info, stderr, address, tty_config) catch return;
-        } else {
-            if (it.getLastError()) |unwind_error|
-                printUnwindError(debug_info, stderr, unwind_error.address, unwind_error.err, tty_config) catch {};
-        }
+        } else printLastUnwindError(&it, debug_info, stderr, tty_config);
     }
 }
 
@@ -734,8 +730,7 @@ pub fn writeCurrentStackTrace(
     defer it.deinit();
 
     while (it.next()) |return_address| {
-        if (it.getLastError()) |unwind_error|
-            try printUnwindError(debug_info, out_stream, unwind_error.address, unwind_error.err, tty_config);
+        printLastUnwindError(&it, debug_info, out_stream, tty_config);
 
         // On arm64 macOS, the address of the last frame is 0x0 rather than 0x1 as on x86_64 macOS,
         // therefore, we do a check for `return_address == 0` before subtracting 1 from it to avoid
@@ -744,10 +739,7 @@ pub fn writeCurrentStackTrace(
         // same behaviour for x86-windows-msvc
         const address = if (return_address == 0) return_address else return_address - 1;
         try printSourceAtAddress(debug_info, out_stream, address, tty_config);
-    } else {
-        if (it.getLastError()) |unwind_error|
-            try printUnwindError(debug_info, out_stream, unwind_error.address, unwind_error.err, tty_config);
-    }
+    } else printLastUnwindError(&it, debug_info, out_stream, tty_config);
 }
 
 pub noinline fn walkStackWindows(addresses: []usize, existing_context: ?*const windows.CONTEXT) usize {
@@ -885,7 +877,14 @@ fn printUnknownSource(debug_info: *DebugInfo, out_stream: anytype, address: usiz
     );
 }
 
-pub fn printUnwindError(debug_info: *DebugInfo, out_stream: anytype, address: usize, err: UnwindError, tty_config: io.tty.Config) !void {
+fn printLastUnwindError(it: *StackIterator, debug_info: *DebugInfo, out_stream: anytype, tty_config: io.tty.Config) void {
+    if (!have_ucontext) return;
+    if (it.getLastError()) |unwind_error| {
+        printUnwindError(debug_info, out_stream, unwind_error.address, unwind_error.err, tty_config) catch {};
+    }
+}
+
+fn printUnwindError(debug_info: *DebugInfo, out_stream: anytype, address: usize, err: UnwindError, tty_config: io.tty.Config) !void {
     const module_name = debug_info.getModuleNameForAddress(address) orelse "???";
     try tty_config.setColor(out_stream, .dim);
     if (err == error.MissingDebugInfo) {