[Lldb-commits] [lldb] [lldb] Find the default source file's main by base name (PR #207043)

[Jonas Devlieghere via lldb-commits]

https://github.com/JDevlieghere created https://github.com/llvm/llvm-project/pull/207043

SourceManager::GetDefaultFileAndLine locates the executable's main to pick a default source file, used for input like "break set -l N" with no file specified. It searched for main by full name, but a function's linkage name can differ from its source name, in which case a full-name search for "main" does not find it and no default file is chosen.

For example, wasi-libc renames main to __main_argc_argv, so on WebAssembly the debug function for main was never matched and "break set -l N" failed with "no default file available".

Search by base name instead. The base name is "main" regardless of the linkage name, and where the two coincide the behavior is unchanged.

>From cebd971d1866bea6857e2a278b23f95ed8b20b6a Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jonas at devlieghere.com>
Date: Wed, 1 Jul 2026 10:59:36 -0700
Subject: [PATCH] [lldb] Find the default source file's main by base name

SourceManager::GetDefaultFileAndLine locates the executable's main to
pick a default source file, used for input like "break set -l N" with no
file specified. It searched for main by full name, but a function's
linkage name can differ from its source name, in which case a full-name
search for "main" does not find it and no default file is chosen.

For example, wasi-libc renames main to __main_argc_argv, so on
WebAssembly the debug function for main was never matched and "break set
-l N" failed with "no default file available".

Search by base name instead. The base name is "main" regardless of the
linkage name, and where the two coincide the behavior is unchanged.
---
 lldb/source/Core/SourceManager.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lldb/source/Core/SourceManager.cpp b/lldb/source/Core/SourceManager.cpp
index d3e1bb5d332f0..af73a2c571c0f 100644
--- a/lldb/source/Core/SourceManager.cpp
+++ b/lldb/source/Core/SourceManager.cpp
@@ -429,8 +429,11 @@ SourceManager::GetDefaultFileAndLine() {
         function_options.include_symbols =
             false; // Force it to be a debug symbol.
         function_options.include_inlines = true;
+        // The linkage name can differ from the source name, so match on the
+        // base name to find the function regardless of how it was mangled or
+        // renamed.
         executable_ptr->FindFunctions(main_name, CompilerDeclContext(),
-                                      lldb::eFunctionNameTypeFull,
+                                      lldb::eFunctionNameTypeBase,
                                       function_options, sc_list);
         for (const SymbolContext &sc : sc_list) {
           if (sc.function) {