From 1b55459da63e53b5dabef481f9d3f8b3bff21933 Mon Sep 17 00:00:00 2001
From: Jon Ross-Perkins <jperkins@google.com>
Date: Fri, 6 Jun 2025 10:29:08 -0700
Subject: [PATCH] Add filenames to stack traces (#5623)

To make it easier to identify crashing files when testing multiple.

```
(elided)
3.	Check::Context
          filename: duplicate_name_same_line.carbon
          NodeStack:
(elided)
```
---
 toolchain/check/context.cpp             | 3 +++
 toolchain/driver/compile_subcommand.cpp | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/toolchain/check/context.cpp b/toolchain/check/context.cpp
index 7bd093af4185..9d067589db2c 100644
--- a/toolchain/check/context.cpp
+++ b/toolchain/check/context.cpp
@@ -81,6 +81,9 @@ auto Context::PrintForStackDump(llvm::raw_ostream& output) const -> void {
   // spaces then add a couple to indent past the Context label.
   constexpr int Indent = 10;
 
+  output.indent(Indent);
+  output << "filename: " << tokens().source().filename() << "\n";
+
   node_stack_.PrintForStackDump(Indent, output);
   inst_block_stack_.PrintForStackDump(Indent, output);
   pattern_block_stack_.PrintForStackDump(Indent, output);
diff --git a/toolchain/driver/compile_subcommand.cpp b/toolchain/driver/compile_subcommand.cpp
index af5b14459f05..8e9a1427323e 100644
--- a/toolchain/driver/compile_subcommand.cpp
+++ b/toolchain/driver/compile_subcommand.cpp
@@ -845,6 +845,9 @@ auto CompilationUnit::GetParseTreeAndSubtrees()
 auto CompilationUnit::LogCall(llvm::StringLiteral logging_label,
                               llvm::StringLiteral timing_label,
                               llvm::function_ref<auto()->void> fn) -> void {
+  PrettyStackTraceFunction trace_file([&](llvm::raw_ostream& out) {
+    out << "filename: " << input_filename_ << "\n";
+  });
   CARBON_VLOG("*** {0}: {1} ***\n", logging_label, input_filename_);
   Timings::ScopedTiming timing(timings_ ? &*timings_ : nullptr, timing_label);
   fn();