Merge pull request #824 from owenv/owenv/swiftc-linker

Miscellaneous fixes for LINKER_DRIVER=auto

Author: owenv

Sources/SWBCore/SpecImplementations/Tools/LinkerTools.swift

@@ -362,6 +362,11 @@ public final class LdLinkerSpec : GenericLinkerSpec, SpecIdentifierType, @unchec
         return runpathSearchPaths
     }
 
+    private static func swiftcSupportsLinkingMachOType(_ type: String) -> Bool {
+        // swiftc does not currently support linking relocatable objects.
+        return type != "mh_object"
+    }
+
     static func resolveLinkerDriver(_ cbc: CommandBuildContext, usedTools: [CommandLineToolSpec: Set<FileTypeSpec>]) -> LinkerDriverChoice {
         switch cbc.scope.evaluate(BuiltinMacros.LINKER_DRIVER) {
         case .clang:
@@ -371,7 +376,7 @@ public final class LdLinkerSpec : GenericLinkerSpec, SpecIdentifierType, @unchec
         case .swiftc:
             return .swiftc
         case .auto:
-            if Self.isUsingSwift(usedTools) {
+            if Self.isUsingSwift(usedTools) && Self.swiftcSupportsLinkingMachOType(cbc.scope.evaluate(BuiltinMacros.MACH_O_TYPE)) {
                 return .swiftc
             } else {
                 return .clang

Sources/SWBUniversalPlatform/Specs/Ld.xcspec

@@ -444,9 +444,24 @@
                 Name = "LINK_WITH_STANDARD_LIBRARIES";
                 Type = Boolean;
                 DefaultValue = YES;
+            },
+            {
+                Name = "CLANG_LINK_WITH_STANDARD_LIBRARIES";
+                Type = Boolean;
+                DefaultValue = "$(LINK_WITH_STANDARD_LIBRARIES)";
                 CommandLineArgs = {
                     NO = ("-nostdlib");
                 };
+                Condition = "$(LINKER_DRIVER) == clang";
+            },
+            {
+                Name = "SWIFTC_LINK_WITH_STANDARD_LIBRARIES";
+                Type = Boolean;
+                DefaultValue = "$(LINK_WITH_STANDARD_LIBRARIES)";
+                CommandLineArgs = {
+                    NO = ("-Xclang-linker", "-nostdlib");
+                };
+                Condition = "$(LINKER_DRIVER) == swiftc";
             },
             {
                 Name = "KEEP_PRIVATE_EXTERNS";