[Driver] Detect libstdc++ include paths for native gcc on 32-bit non-Debian Linux

[MaskRay]

Summary

Fixes https://bugs.llvm.org/show_bug.cgi?id=50303

I use archlinux32 as an example. Its gcc --print-multiarch is empty.

[lbenes]

Thanks for looking into this. On OpenSUSE i686, the failing tests are now fixed, but Driver/linux-cross.cpp fails with:

https://pastebin.com/uHfi3KD1

Would you like any more debugging info?

gcc --print-multiarch

is also empty.

[MaskRay]

In D106119#2884412, @lbenes wrote:

Thanks for looking into this. On OpenSUSE i686, the failing tests are now fixed, but Driver/linux-cross.cpp fails with:

https://pastebin.com/uHfi3KD1

"This page is no longer available. It has either expired, been removed by its creator, or removed by one of the Pastebin staff."

Would you like any more debugging info?

gcc --print-multiarch

is also empty.

[lbenes]

This one should work.
https://controlc.com/505d58d3

Please let me know if there's anything else that could help.

[MaskRay]

Add two .keep files to keep two directories

[MaskRay]

In D106119#2884915, @lbenes wrote:

This one should work.
https://controlc.com/505d58d3

Please let me know if there's anything else that could help.

Thanks. I forgot to add two .keep files to retain two otherwise empty directories. Should be good now.

[lbenes]

Still seeing the same failure on OpenSUSE. I'm still on gcc 10.3. Should I need to upgrade for this to work?

[lbenes]

Updated OpenSUSE which bumped gcc from 10 to 11. Still failing with the latest patch.

https://controlc.com/c4a19d64

[MaskRay]

fix test

[MaskRay]

If you can accept this, I'll submit it.

[lbenes]

LGTM. No more test failures or build errors. And the libreoffice .configure error has been resolved now too. Thanks!

clang/lib/Driver/ToolChains/Gnu.cpp

 bool Generic_GCC::addLibStdCXXIncludePaths(Twine IncludeDir, StringRef Triple,
                                            Twine IncludeSuffix,
                                            const llvm::opt::ArgList &DriverArgs,
                                            llvm::opt::ArgStringList &CC1Args,
                                            bool DetectDebian) const {
   if (!getVFS().exists(IncludeDir))
     return false;
 
-  // GPLUSPLUS_INCLUDE_DIR
-  addSystemInclude(DriverArgs, CC1Args, IncludeDir);
-  // GPLUSPLUS_TOOL_INCLUDE_DIR. If Triple is not empty, add a target-dependent
-  // include directory.
-  if (!Triple.empty()) {
-    if (DetectDebian) {
-      // Debian native gcc has an awful patch g++-multiarch-incdir.diff which
-      // uses include/x86_64-linux-gnu/c++/10$IncludeSuffix instead of
-      // include/c++/10/x86_64-linux-gnu$IncludeSuffix.
-      std::string Dir = IncludeDir.str();
-      StringRef Include =
-          llvm::sys::path::parent_path(llvm::sys::path::parent_path(Dir));
-      std::string Path =
-          (Include + "/" + Triple + Dir.substr(Include.size()) + IncludeSuffix)
-              .str();
-      if (getVFS().exists(Path))
-        addSystemInclude(DriverArgs, CC1Args, Path);
-      else
-        addSystemInclude(DriverArgs, CC1Args,
-                         IncludeDir + "/" + Triple + IncludeSuffix);
-    } else {
-      addSystemInclude(DriverArgs, CC1Args,
-                       IncludeDir + "/" + Triple + IncludeSuffix);
-    }
-  }
+  // Debian native gcc uses g++-multiarch-incdir.diff which uses
+  // include/x86_64-linux-gnu/c++/10$IncludeSuffix instead of
+  if (DetectDebian && !getVFS().exists(Path))
+    return false;
+
+  // GPLUSPLUS_INCLUDE_DIR
+  addSystemInclude(DriverArgs, CC1Args, IncludeDir);
+  // GPLUSPLUS_TOOL_INCLUDE_DIR. If Triple is not empty, add a target-dependent
+  // include directory.
+  if (DetectDebian)
+  else if (!Triple.empty())
   // GPLUSPLUS_BACKWARD_INCLUDE_DIR
   addSystemInclude(DriverArgs, CC1Args, IncludeDir + "/backward");
   return true;
 }
 
 bool Generic_GCC::addGCCLibStdCxxIncludePaths(
     const llvm::opt::ArgList &DriverArgs, llvm::opt::ArgStringList &CC1Args,
     StringRef DebianMultiarch) const {
   assert(GCCInstallation.isValid());
 
   // By default, look for the C++ headers in an include directory adjacent to
   // the lib directory of the GCC installation. Note that this is expect to be
   // equivalent to '/usr/include/c++/X.Y' in almost all cases.
   StringRef LibDir = GCCInstallation.getParentLibPath();
   StringRef InstallDir = GCCInstallation.getInstallPath();
   StringRef TripleStr = GCCInstallation.getTriple().str();
   const Multilib &Multilib = GCCInstallation.getMultilib();
   const GCCVersion &Version = GCCInstallation.getVersion();
 
-  // Try /../$triple/include/c++/$version then /../include/c++/$version.
+  // Try /../$triple/include/c++/$version (gcc --print-multiarch is not empty).
   if (addLibStdCXXIncludePaths(
           LibDir.str() + "/../" + TripleStr + "/include/c++/" + Version.Text,
           TripleStr, Multilib.includeSuffix(), DriverArgs, CC1Args))
     return true;
 
   // Detect Debian g++-multiarch-incdir.diff.
   if (addLibStdCXXIncludePaths(LibDir.str() + "/../include/c++/" + Version.Text,
                                DebianMultiarch, Multilib.includeSuffix(),
                                DriverArgs, CC1Args, /*Debian=*/true))
     return true;
 
+  // Try /../include/c++/$version (gcc --print-multiarch is empty).
+  if (addLibStdCXXIncludePaths(LibDir.str() + "/../include/c++/" + Version.Text,
+                               TripleStr, Multilib.includeSuffix(), DriverArgs,
+                               CC1Args))
+    return true;
+
   // Otherwise, fall back on a bunch of options which don't use multiarch
   // layouts for simplicity.
   const std::string LibStdCXXIncludePathCandidates[] = {
       // Gentoo is weird and places its headers inside the GCC install,
       // so if the first attempt to find the headers fails, try these patterns.
       InstallDir.str() + "/include/g++-v" + Version.Text,
       InstallDir.str() + "/include/g++-v" + Version.MajorStr + "." +
           Version.MinorStr,

clang/test/Driver/linux-cross.cpp

 // UNSUPPORTED: system-windows
 
+/// Test native GCC installation on Arch Linux i686.
+// RUN: %clang -### %s --target=i686-linux-gnu --sysroot=%S/Inputs/archlinux_i686_tree \
+// RUN:   -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin -resource-dir=%S/Inputs/resource_dir \
+// RUN:   --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=ARCH_I686
+// ARCH_I686:      "-resource-dir" "[[RESOURCE:[^"]+]]"
+// ARCH_I686:      "-internal-isystem"
+// ARCH_I686-SAME: {{^}} "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-pc-linux-gnu/11.1.0/../../../../include/c++/11.1.0"
+// ARCH_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-pc-linux-gnu/11.1.0/../../../../include/c++/11.1.0/i686-pc-linux-gnu"
+// ARCH_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-pc-linux-gnu/11.1.0/../../../../include/c++/11.1.0/backward"
+// ARCH_I686-SAME: {{^}} "-internal-isystem" "[[RESOURCE]]/include"
+// ARCH_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT]]/usr/local/include"
+/// This resolves to /usr/i686-linux-gnu/include. Because it does not exist,
+/// having it does no harm albeit not ideal.
+// ARCH_I686-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/i686-pc-linux-gnu/11.1.0/../../../../i686-pc-linux-gnu/include"
+// ARCH_I686:      "-internal-externc-isystem"
+// ARCH_I686-SAME: {{^}} "[[SYSROOT]]/include"
+// ARCH_I686-SAME: {{^}} "-internal-externc-isystem" "[[SYSROOT]]/usr/include"
+// ARCH_I686:      "-L
+// ARCH_I686-SAME: {{^}}[[SYSROOT]]/usr/lib/gcc/i686-pc-linux-gnu/11.1.0"
+// ARCH_I686-SAME: {{^}} "-L[[SYSROOT]]/lib"
+// ARCH_I686-SAME: {{^}} "-L[[SYSROOT]]/usr/lib"
+
 /// Test native x86-64 in the tree.
 // RUN: %clang -### %s --target=x86_64-linux-gnu --sysroot=%S/Inputs/debian_multiarch_tree \
 // RUN:   -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin -resource-dir=%S/Inputs/resource_dir \
 // RUN:   --stdlib=platform --rtlib=platform 2>&1 | FileCheck %s --check-prefix=DEBIAN_X86_64
 // DEBIAN_X86_64:      "-resource-dir" "[[RESOURCE:[^"]+]]"
 // DEBIAN_X86_64:      "-internal-isystem"
 // DEBIAN_X86_64-SAME: {{^}} "[[SYSROOT:[^"]+]]/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10"
 // DEBIAN_X86_64-SAME: {{^}} "-internal-isystem" "[[SYSROOT:[^"]+]]/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10"