[LLD] [MinGW] Support setting the subsystem version via the subsystem argument

[mstorsjo]

Summary

If a version is specified both with --{major,minor}-subsystem-version and with --subsystem <name>:<version>, the one specified last (that actually sets a version) takes precedance in GNU ld; thus doing the same here.

[mati865]

With BFD (tested version 2.35) the latter specified option takes precedence:

$ gcc clear.c -Wl,--subsystem,windows:7.8,--major-subsystem-version,2,--minor-subsystem-version,3
$ llvm-readobj -h a.exe | grep SubsystemVersion
  MajorSubsystemVersion: 2
  MinorSubsystemVersion: 3

$ gcc clear.c -Wl,--major-subsystem-version,2,--minor-subsystem-version,3,--subsystem,windows:7.8
$ llvm-readobj -h a.exe | grep SubsystemVersion
  MajorSubsystemVersion: 7
  MinorSubsystemVersion: 8

[mstorsjo]

In D88804#2311497, @mati865 wrote:

With BFD (tested version 2.35) the latter specified option takes precedence:

$ gcc clear.c -Wl,--subsystem,windows:7.8,--major-subsystem-version,2,--minor-subsystem-version,3
$ llvm-readobj -h a.exe | grep SubsystemVersion
  MajorSubsystemVersion: 2
  MinorSubsystemVersion: 3

$ gcc clear.c -Wl,--major-subsystem-version,2,--minor-subsystem-version,3,--subsystem,windows:7.8
$ llvm-readobj -h a.exe | grep SubsystemVersion
  MajorSubsystemVersion: 7
  MinorSubsystemVersion: 8

Oh, tricky. Will have to see if we can match that with reasonable effort...

[mstorsjo]

Updated to iterate over --{major,minor}-subsystem-version and --subsystem, to pick the version from the last one that specifies it.

lld/MinGW/Driver.cpp

if (auto *a = args.getLastArg(OPT_entry)) {
     else
       add("-entry:" + s);
   }
 
   if (args.hasArg(OPT_major_os_version, OPT_minor_os_version,
                   OPT_major_subsystem_version, OPT_minor_subsystem_version)) {
     StringRef majOSVer = args.getLastArgValue(OPT_major_os_version, "6");
     StringRef minOSVer = args.getLastArgValue(OPT_minor_os_version, "0");
-    StringRef majSubSysVer = args.getLastArgValue(OPT_major_subsystem_version, "6");
-    StringRef minSubSysVer = args.getLastArgValue(OPT_minor_subsystem_version, "0");
-    StringRef subSys = args.getLastArgValue(OPT_subs, "default");
+    StringRef majSubSysVer = "6";
+    StringRef minSubSysVer = "0";
+    StringRef subSysName = "default";
+    StringRef subSysVer;
+    // Iterate over --{major,minor}-subsystem-version and --subsystem, and pick
+    // the version number components from the last one of them that specifies
+    // a version.
+    for (auto *a : args.filtered(OPT_major_subsystem_version,
+                                 OPT_minor_subsystem_version, OPT_subs)) {
+      switch (a->getOption().getID()) {
+      case OPT_major_subsystem_version:
+        majSubSysVer = a->getValue();
+        break;
+      case OPT_minor_subsystem_version:
+        minSubSysVer = a->getValue();
+        break;
+      case OPT_subs:
+        std::tie(subSysName, subSysVer) = StringRef(a->getValue()).split(':');
+        if (!subSysVer.empty()) {
+          if (subSysVer.contains('.'))
+            std::tie(majSubSysVer, minSubSysVer) = subSysVer.split('.');
+          else
+            majSubSysVer = subSysVer;
+        }
+        break;
+      }
+    }
     add("-osversion:" + majOSVer + "." + minOSVer);
-    add("-subsystem:" + subSys + "," + majSubSysVer + "." + minSubSysVer);
-  } else if (auto *a = args.getLastArg(OPT_subs)) {
-    add("-subsystem:" + StringRef(a->getValue()));
+    add("-subsystem:" + subSysName + "," + majSubSysVer + "." + minSubSysVer);
+  } else if (args.hasArg(OPT_subs)) {
+    StringRef subSys = args.getLastArgValue(OPT_subs, "default");
+    StringRef subSysName, subSysVer;
+    std::tie(subSysName, subSysVer) = subSys.split(':');
+    StringRef sep = subSysVer.empty() ? "" : ",";
+    add("-subsystem:" + subSysName + sep + subSysVer);
   }
 
   if (auto *a = args.getLastArg(OPT_out_implib))
     add("-implib:" + StringRef(a->getValue()));
   if (auto *a = args.getLastArg(OPT_stack))
     add("-stack:" + StringRef(a->getValue()));
   if (auto *a = args.getLastArg(OPT_output_def))
     add("-output-def:" + StringRef(a->getValue()));

lld/test/MinGW/driver.test

 
 RUN: ld.lld -### foo.o -m i386pep --minor-subsystem-version 8 | FileCheck -check-prefix=SUBSYSTEM_DEFAULT_MAJOR %s
 SUBSYSTEM_DEFAULT_MAJOR: -subsystem:default,6.8
 
 RUN: ld.lld -### foo.o -m i386pep --major-subsystem-version 7 | FileCheck -check-prefix=SUBSYSTEM_DEFAULT_MINOR %s
 SUBSYSTEM_DEFAULT_MINOR: -subsystem:default,7.0
 
 RUN: ld.lld -### foo.o -m i386pep --subsystem windows --major-subsystem-version 7 --minor-subsystem-version 8 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
+RUN: ld.lld -### foo.o -m i386pep --major-subsystem-version 7 --minor-subsystem-version 8 --subsystem windows | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
+RUN: ld.lld -### foo.o -m i386pep --subsystem windows:7.8 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
+RUN: ld.lld -### foo.o -m i386pep --subsystem windows:2.3 --major-subsystem-version 7 --minor-subsystem-version 8 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
+RUN: ld.lld -### foo.o -m i386pep --subsystem windows:7.8 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
+RUN: ld.lld -### foo.o -m i386pep --major-subsystem-version 2 --minor-subsystem-version 3 --subsystem windows:7.8 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
+RUN: ld.lld -### foo.o -m i386pep --major-subsystem-version 2 --minor-subsystem-version 8 --subsystem windows:7 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
 SUBSYSTEM_WINDOWS: -subsystem:windows,7.8
 
 RUN: ld.lld -### foo.o -m i386pep -stack 4194304,8192 | FileCheck -check-prefix=STACK %s
 RUN: ld.lld -### foo.o -m i386pep --stack 4194304,8192 | FileCheck -check-prefix=STACK %s
 STACK: -stack:4194304,8192
 
 RUN: ld.lld -### foo.o -m i386pep -verbose | FileCheck -check-prefix=VERBOSE %s
 RUN: ld.lld -### foo.o -m i386pep --verbose | FileCheck -check-prefix=VERBOSE %s