[Driver] Refactor DetectDistro() parameters to take VFS ref only. NFC

Refactor the DetectDistro() function to take a single vfs::FileSystem
reference only, instead of Driver and llvm::Triple::ArchType.
The ArchType parameter was not used anyway, and Driver was only used to
obtain the VFS.

Aside to making the API simpler and more transparent, it makes it
easier to add unit tests for the function in the future -- since
the tests would need only to provide an appropriate VFS.

Differential Revision: https://reviews.llvm.org/D25819

llvm-svn: 284774

clang/lib/Driver/ToolChains.cpp

@@ -3850,9 +3850,9 @@ static bool IsUbuntu(enum Distro Distro) {
   return Distro >= UbuntuHardy && Distro <= UbuntuYakkety;
 }
 
-static Distro DetectDistro(const Driver &D, llvm::Triple::ArchType Arch) {
+static Distro DetectDistro(vfs::FileSystem &VFS) {
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> File =
-      D.getVFS().getBufferForFile("/etc/lsb-release");
+      VFS.getBufferForFile("/etc/lsb-release");
   if (File) {
     StringRef Data = File.get()->getBuffer();
     SmallVector<StringRef, 16> Lines;
@@ -3884,7 +3884,7 @@ static Distro DetectDistro(const Driver &D, llvm::Triple::ArchType Arch) {
       return Version;
   }
 
-  File = D.getVFS().getBufferForFile("/etc/redhat-release");
+  File = VFS.getBufferForFile("/etc/redhat-release");
   if (File) {
     StringRef Data = File.get()->getBuffer();
     if (Data.startswith("Fedora release"))
@@ -3902,7 +3902,7 @@ static Distro DetectDistro(const Driver &D, llvm::Triple::ArchType Arch) {
     return UnknownDistro;
   }
 
-  File = D.getVFS().getBufferForFile("/etc/debian_version");
+  File = VFS.getBufferForFile("/etc/debian_version");
   if (File) {
     StringRef Data = File.get()->getBuffer();
     // Contents: < major.minor > or < codename/sid >
@@ -3931,13 +3931,13 @@ static Distro DetectDistro(const Driver &D, llvm::Triple::ArchType Arch) {
         .Default(UnknownDistro);
   }
 
-  if (D.getVFS().exists("/etc/SuSE-release"))
+  if (VFS.exists("/etc/SuSE-release"))
     return OpenSUSE;
 
-  if (D.getVFS().exists("/etc/exherbo-release"))
+  if (VFS.exists("/etc/exherbo-release"))
     return Exherbo;
 
-  if (D.getVFS().exists("/etc/arch-release"))
+  if (VFS.exists("/etc/arch-release"))
     return ArchLinux;
 
   return UnknownDistro;
@@ -4122,7 +4122,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
                          GCCInstallation.getTriple().str() + "/bin")
                        .str());
 
-  Distro Distro = DetectDistro(D, Arch);
+  Distro Distro = DetectDistro(D.getVFS());
 
   if (IsOpenSUSE(Distro) || IsUbuntu(Distro)) {
     ExtraOpts.push_back("-z");
@@ -4326,7 +4326,7 @@ std::string Linux::getDynamicLinker(const ArgList &Args) const {
   const llvm::Triple::ArchType Arch = getArch();
   const llvm::Triple &Triple = getTriple();
 
-  const enum Distro Distro = DetectDistro(getDriver(), Arch);
+  const enum Distro Distro = DetectDistro(getDriver().getVFS());
 
   if (Triple.isAndroid())
     return Triple.isArch64Bit() ? "/system/bin/linker64" : "/system/bin/linker";