[clang] [Distro] Support detecting Gentoo

[mgorny]

Summary

Add support for distinguishing plain Gentoo distribution, and a unit
test for it. This is going to be used to introduce distro-specific
customizations in the driver code; most notably, it is going to be used
to disable -faddrsig.

[phosek]

LGTM

include/clang/Driver/Distro.h

118

Shall we also introduce the IsGentoo() predicate for convenience?

[mgorny]

include/clang/Driver/Distro.h

118

Hmm, I originally thought they only make sense when there's 1+ distro value for it. But I guess more distros are doing it for some reason.

[mgorny]

Now with IsGentoo() predicate.

include/clang/Driver/Distro.h

enum DistroType {
     DebianJessie,
     DebianStretch,
     DebianBuster,
     Exherbo,
     RHEL5,
     RHEL6,
     RHEL7,
     Fedora,
+    Gentoo,
     OpenSUSE,
     UbuntuHardy,
     UbuntuIntrepid,
     UbuntuJaunty,
     UbuntuKarmic,
     UbuntuLucid,
     UbuntuMaverick,
     UbuntuNatty,
public:
 
   bool IsOpenSUSE() const {
     return DistroVal == OpenSUSE;
   }
 
   bool IsDebian() const {
     return DistroVal >= DebianLenny && DistroVal <= DebianBuster;
   }
 
   bool IsUbuntu() const {
     return DistroVal >= UbuntuHardy && DistroVal <= UbuntuDisco;
   }
 
   bool IsAlpineLinux() const {
     return DistroVal == AlpineLinux;
   }
 
   /// @}
 };
 
 } // end namespace driver
 } // end namespace clang
 
 #endif

lib/Driver/Distro.cpp

if (VFS.exists("/etc/exherbo-release"))
     return Distro::Exherbo;
 
   if (VFS.exists("/etc/alpine-release"))
     return Distro::AlpineLinux;
 
   if (VFS.exists("/etc/arch-release"))
     return Distro::ArchLinux;
 
+  if (VFS.exists("/etc/gentoo-release"))
+    return Distro::Gentoo;
+
   return Distro::UnknownDistro;
 }
 
 Distro::Distro(llvm::vfs::FileSystem &VFS) : DistroVal(DetectDistro(VFS)) {}

unittests/Driver/DistroTest.cpp

TEST(DistroTest, DetectArchLinux) {
   Distro ArchLinux{ArchLinuxFileSystem};
   ASSERT_EQ(Distro(Distro::ArchLinux), ArchLinux);
   ASSERT_FALSE(ArchLinux.IsUbuntu());
   ASSERT_FALSE(ArchLinux.IsRedhat());
   ASSERT_FALSE(ArchLinux.IsOpenSUSE());
   ASSERT_FALSE(ArchLinux.IsDebian());
 }
 
+TEST(DistroTest, DetectGentoo) {
+  llvm::vfs::InMemoryFileSystem GentooFileSystem;
+  GentooFileSystem.addFile(
+      "/etc/gentoo-release", 0,
+      llvm::MemoryBuffer::getMemBuffer("Gentoo Base System release 2.6"));
+  GentooFileSystem.addFile(
+      "/etc/os-release", 0,
+      llvm::MemoryBuffer::getMemBuffer(
+          "NAME=Gentoo\n"
+          "ID=gentoo\n"
+          "PRETTY_NAME=\"Gentoo/Linux\"\n"
+          "ANSI_COLOR=\"1;32\"\n"
+          "HOME_URL=\"https://www.gentoo.org/\"\n"
+          "SUPPORT_URL=\"https://www.gentoo.org/support/\"\n"
+          "BUG_REPORT_URL=\"https://bugs.gentoo.org/\"\n"));
+
+  Distro Gentoo{GentooFileSystem};
+  ASSERT_EQ(Distro(Distro::Gentoo), Gentoo);
+  ASSERT_FALSE(Gentoo.IsUbuntu());
+  ASSERT_FALSE(Gentoo.IsRedhat());
+  ASSERT_FALSE(Gentoo.IsOpenSUSE());
+  ASSERT_FALSE(Gentoo.IsDebian());
+}
+
 } // end anonymous namespace