CLI: ignore -lgcc_s when it is redundant with compiler-rt

For some projects, they can't help themselves, -lgcc_s ends up on the
compiler command line even though it does not belong there. In Zig we
know what -lgcc_s does. It's an alternative to compiler-rt. With this
commit we emit a warning telling that it is unnecessary to put such
thing on the command line, and happily ignore it, since we will fulfill
the dependency with compiler-rt.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/main.zig b/src/main.zig
index 3f38fd1f78..75655d6a2a 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -2010,6 +2010,11 @@ fn buildOutputType(
                 _ = system_libs.orderedRemove(lib_name);
                 continue;
             }
+            if (target_util.is_compiler_rt_lib_name(target_info.target, lib_name)) {
+                std.log.warn("ignoring superfluous library '{s}': this dependency is fulfilled instead by compiler-rt which zig unconditionally provides", .{lib_name});
+                _ = system_libs.orderedRemove(lib_name);
+                continue;
+            }
             if (std.fs.path.isAbsolute(lib_name)) {
                 fatal("cannot use absolute path as a system library: {s}", .{lib_name});
             }