set default linker to lld for Amazon Linux 2023

Author: futurejones

CMakeLists.txt

@@ -948,6 +948,10 @@ if(XCODE)
   swift_common_xcode_cxx_config()
 endif()
 
+# Check what linux distribution is being used.
+# This can be used to determine the default linker to use.
+cmake_host_system_information(RESULT DISTRO_NAME  QUERY DISTRIB_PRETTY_NAME)
+
 # Which default linker to use. Prefer LLVM_USE_LINKER if it set, otherwise use
 # our own defaults. This should only be possible in a unified (not stand alone)
 # build environment.
@@ -959,6 +963,8 @@ elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows" AND NOT CMAKE_HOST_SYSTEM_NAME STREQ
   set(SWIFT_USE_LINKER_default "lld")
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   set(SWIFT_USE_LINKER_default "")
+elseif(DISTRO_NAME STREQUAL "Amazon Linux 2023")
+  set(SWIFT_USE_LINKER_default "lld")
 else()
   set(SWIFT_USE_LINKER_default "gold")
 endif()

lib/Driver/UnixToolChains.cpp

@@ -9,6 +9,8 @@
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//
+#include <iostream>
+#include <fstream>
 
 #include "ToolChains.h"
 
@@ -108,8 +110,22 @@ ToolChain::InvocationInfo toolchains::GenericUnix::constructInvocation(
 
   return II;
 }
-
+// Amazon Linux 2023 requires lld as the default linker.
 std::string toolchains::GenericUnix::getDefaultLinker() const {
+  if (getTriple().isOSLinux()) {
+    std::ifstream file("/etc/os-release");
+    std::string line;
+
+    while (std::getline(file, line)) {
+      if (line.substr(0, 12) == "PRETTY_NAME=") {
+        if (line.substr(12) == "\"Amazon Linux 2023\"") {
+          file.close();
+          return "lld";
+        }
+      }
+    }
+  }
+
   if (getTriple().isAndroid())
     return "lld";