frontend: fix "any" default resolution ambiguity

In Compilation.create, update the resolved config to account for the
default resolution of the root module. This makes it so that, for
example, reading comp.config.any_non_single_threaded is valid in order
to determine whether any module has single_threaded=false.

1 files changed, 12 insertions, 1 deletions

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 00d6ec3193..15b507b7a4 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -1198,7 +1198,12 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
 
         const use_llvm = options.config.use_llvm;
 
-        const any_unwind_tables = options.config.any_unwind_tables;
+        // The "any" values provided by resolved config only account for
+        // explicitly-provided settings. We now make them additionally account
+        // for default setting resolution.
+        const any_unwind_tables = options.config.any_unwind_tables or options.root_mod.unwind_tables;
+        const any_non_single_threaded = options.config.any_non_single_threaded or !options.root_mod.single_threaded;
+        const any_sanitize_thread = options.config.any_sanitize_thread or options.root_mod.sanitize_thread;
 
         const link_eh_frame_hdr = options.link_eh_frame_hdr or any_unwind_tables;
         const build_id = options.build_id orelse .none;
@@ -1503,6 +1508,12 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
             .native_system_include_paths = options.native_system_include_paths,
         };
 
+        // Prevent some footguns by making the "any" fields of config reflect
+        // the default Module settings.
+        comp.config.any_unwind_tables = any_unwind_tables;
+        comp.config.any_non_single_threaded = any_non_single_threaded;
+        comp.config.any_sanitize_thread = any_sanitize_thread;
+
         const lf_open_opts: link.File.OpenOptions = .{
             .linker_script = options.linker_script,
             .z_nodelete = options.linker_z_nodelete,