From 679f5a7d64637de9a1cf46db57d93832a3727e3d Mon Sep 17 00:00:00 2001
From: Relintai <relintai@protonmail.com>
Date: Fri, 29 Jul 2022 23:18:06 +0200
Subject: [PATCH] Ported:  SCons: Refactor Linux linker options with
 linker=<bfd|gold|lld|mold> The new option is `linker` and lets the user
 specify the argument to the`-fuse_ld=` linker flag directly. The supported
 options are: - `default`: No change, typically uses GNU ld (bfd) unless the
 user or   distro picked a different default `/usr/bin/ld`. - `bfd`: GNU ld
 from binutils - `gold`: GNU gold from binutils - `lld`: lld from LLVM -
 `mold`: mold, an extremely fast modern linker, not (yet) intended for   use
 in production but great for development speed. Provided by distro   `mold`
 package or needs to be compiled from source and installed to   `/usr`
 otherwise. Deprecates the `use_lld=yes` option, and make lld actually usable
 with GCC too. Not all the above are compatible or recommend for LTO, we
 recommend using GNU ld with GCC LTO, or lld with LLVM ThinLTO. - akien-mga
 https://github.com/godotengine/godot/commit/5bb3063eecc44ae19e4f679c866c42014e8f495d

---
 platform/x11/detect.py | 55 ++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 16 deletions(-)

diff --git a/platform/x11/detect.py b/platform/x11/detect.py
index b7fc68059..6fadcca55 100644
--- a/platform/x11/detect.py
+++ b/platform/x11/detect.py
@@ -64,9 +64,10 @@ def get_opts():
     from SCons.Variables import BoolVariable, EnumVariable
 
     return [
+        EnumVariable("linker", "Linker program", "default", ("default", "bfd", "gold", "lld", "mold")),
         BoolVariable("use_llvm", "Use the LLVM compiler", False),
-        BoolVariable("use_lld", "Use the LLD linker", False),
-        BoolVariable("use_thinlto", "Use ThinLTO", False),
+        BoolVariable("use_lld", "Use the LLD linker (deprecated, use `linker=lld` instead).", False),
+        BoolVariable("use_thinlto", "Use ThinLTO (LLVM only, requires linker=lld, implies use_lto=yes)", False),
         BoolVariable("use_static_cpp", "Link libgcc and libstdc++ statically for better portability", True),
         BoolVariable("use_ubsan", "Use LLVM/GCC compiler undefined behavior sanitizer (UBSAN)", False),
         BoolVariable("use_asan", "Use LLVM/GCC compiler address sanitizer (ASAN))", False),
@@ -146,14 +147,37 @@ def configure(env):
         env.extra_suffix = ".llvm" + env.extra_suffix
 
     if env["use_lld"]:
-        if env["use_llvm"]:
-            env.Append(LINKFLAGS=["-fuse-ld=lld"])
-            if env["use_thinlto"]:
-                # A convenience so you don't need to write use_lto too when using SCons
-                env["use_lto"] = True
-        else:
-            print("Using LLD with GCC is not supported yet. Try compiling with 'use_llvm=yes'.")
+        if env["linker"] != "default":
+            print("Can't specify both `use_lld=yes` and a non-default `linker`. Remove `use_lld=yes`.")
             sys.exit(255)
+        print("The `use_lld=yes` option is deprecated, use `linker=lld` instead.")
+        env["linker"] == "lld"
+
+    if env["linker"] != "default":
+        print("Using linker program: " + env["linker"])
+        if env["linker"] == "mold" and using_gcc(env):  # GCC < 12.1 doesn't support -fuse-ld=mold.
+            cc_semver = tuple(get_compiler_version(env))
+            if cc_semver < (12, 1):
+                found_wrapper = False
+                for path in ["/usr/libexec", "/usr/local/libexec", "/usr/lib", "/usr/local/lib"]:
+                    if os.path.isfile(path + "/mold/ld"):
+                        env.Append(LINKFLAGS=["-B" + path + "/mold"])
+                        found_wrapper = True
+                        break
+                if not found_wrapper:
+                    print("Couldn't locate mold installation path. Make sure it's installed in /usr or /usr/local.")
+                    sys.exit(255)
+            else:
+                env.Append(LINKFLAGS=["-fuse-ld=mold"])
+        else:
+            env.Append(LINKFLAGS=["-fuse-ld=%s" % env["linker"]])
+
+    if env["use_thinlto"]:
+        if not env["use_llvm"] or env["linker"] != "lld":
+            print("ThinLTO is only compatible with LLVM and the LLD linker, use `use_llvm=yes linker=lld`.")
+            sys.exit(255)
+        else:
+            env["use_lto"] = True  # ThinLTO implies LTO
 
     if env["use_ubsan"] or env["use_asan"] or env["use_lsan"] or env["use_tsan"] or env["use_msan"]:
         env.extra_suffix += "s"
@@ -192,16 +216,15 @@ def configure(env):
             env.Append(LINKFLAGS=["-fsanitize=memory"])
 
     if env["use_lto"]:
-        if not env["use_llvm"] and env.GetOption("num_jobs") > 1:
+        if env["use_thinlto"]:
+            env.Append(CCFLAGS=["-flto=thin"])
+            env.Append(LINKFLAGS=["-flto=thin"])
+        elif not env["use_llvm"] and env.GetOption("num_jobs") > 1:
             env.Append(CCFLAGS=["-flto"])
             env.Append(LINKFLAGS=["-flto=" + str(env.GetOption("num_jobs"))])
         else:
-            if env["use_lld"] and env["use_thinlto"]:
-                env.Append(CCFLAGS=["-flto=thin"])
-                env.Append(LINKFLAGS=["-flto=thin"])
-            else:
-                env.Append(CCFLAGS=["-flto"])
-                env.Append(LINKFLAGS=["-flto"])
+            env.Append(CCFLAGS=["-flto"])
+            env.Append(LINKFLAGS=["-flto"])
 
         if not env["use_llvm"]:
             env["RANLIB"] = "gcc-ranlib"