[PATCH] D138693: [clang] [MinGW] Improve detection of libstdc++ headers on Fedora

[Martin Storsjö via Phabricator via cfe-commits]

mstorsjo created this revision.
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There's some variation in where different toolchain distributions
(and linux distributions) package the mingw sysroots - this is
so far handled by adding specific known subdirectory paths
to the include and lib directory lists.

There are multiple degrees of combinatorics involved here though;
the distros may use different locations such as
/usr/x86_64-w64-mingw32/include or
/usr/x86_64-w64-mingw32/sys-root/mingw/include.

So far, this setup has been treated as base=/usr, subdir=x86_64-w64-mingw32,
and the driver tries to add further subdirectories such as
<base>/<subdir>/include, <base>/<subdir>/sys-root/mingw/include.

When it comes to libstdc++ (and libc++), each of these come with
a large number of potential subdirectories. Instead of further
exploding the combinatorics another step by adding all combinations
of all paths, check whether <base>/<subdir>/sys-root/mingw/include
exists, and if it does, append that subpath into the subdir variable.

This allows finding libstdc++ headers in e.g.
/usr/x86_64-w64-mingw32/sys-root/mingw/include/c++/x86_64-w64-mingw32
on Fedora.

The same logic (where everything belonging to this target fits
under one expanded <subdir> path, with just /include and /lib
under it) doesn't seem to apply on Gentoo, where the includes
are found in <base>/<subdir>/usr/include while the libraries
are in <base>/<subdir>/mingw/lib (see
8e218026f8d5eabfdef9141ae5e26aa91d1933e6 <https://reviews.llvm.org/rG8e218026f8d5eabfdef9141ae5e26aa91d1933e6>). But apparently
the libstdc++ headers aren't installed under
<base>/<subdir>/usr/include, so that path hierarchy quirk doesn't
need to be taken into account in AddClangCXXStdlibIncludeArgs.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D138693

Files:
  clang/lib/Driver/ToolChains/MinGW.cpp
  clang/lib/Driver/ToolChains/MinGW.h
  clang/test/Driver/mingw.cpp


Index: clang/test/Driver/mingw.cpp
===================================================================
--- clang/test/Driver/mingw.cpp
+++ clang/test/Driver/mingw.cpp
@@ -40,7 +40,10 @@
 
 
 // RUN: %clang -target x86_64-pc-windows-gnu -rtlib=platform -stdlib=libstdc++ -c -### --sysroot=%S/Inputs/mingw_fedora_tree/usr %s 2>&1 | FileCheck -check-prefix=CHECK_MINGW_FEDORA_TREE %s
-// CHECK_MINGW_FEDORA_TREE: "[[BASE:[^"]+]]/Inputs/mingw_fedora_tree/usr{{/|\\\\}}x86_64-w64-mingw32ucrt/sys-root/mingw/include"
+// CHECK_MINGW_FEDORA_TREE: "[[BASE:[^"]+]]/Inputs/mingw_fedora_tree/usr{{/|\\\\}}x86_64-w64-mingw32ucrt/sys-root/mingw/include/c++"
+// CHECK_MINGW_FEDORA_TREE: "[[BASE]]/Inputs/mingw_fedora_tree/usr{{/|\\\\}}x86_64-w64-mingw32ucrt/sys-root/mingw/include/c++/x86_64-w64-mingw32ucrt"
+// CHECK_MINGW_FEDORA_TREE: "[[BASE]]/Inputs/mingw_fedora_tree/usr{{/|\\\\}}x86_64-w64-mingw32ucrt/sys-root/mingw/include/c++/backward"
+// CHECK_MINGW_FEDORA_TREE: "[[BASE]]/Inputs/mingw_fedora_tree/usr{{/|\\\\}}x86_64-w64-mingw32ucrt/sys-root/mingw/include"
 
 
 // RUN: %clang -target i686-pc-windows-gnu -rtlib=platform -stdlib=libstdc++ -c -### --sysroot=%S/Inputs/mingw_arch_tree/usr %s 2>&1 | FileCheck -check-prefix=CHECK_MINGW_ARCH_TREE %s
Index: clang/lib/Driver/ToolChains/MinGW.h
===================================================================
--- clang/lib/Driver/ToolChains/MinGW.h
+++ clang/lib/Driver/ToolChains/MinGW.h
@@ -111,6 +111,7 @@
   clang::driver::toolchains::Generic_GCC::GCCVersion GccVer;
   std::string Ver;
   std::string SubdirName;
+  std::string TripleDirName;
   mutable std::unique_ptr<tools::gcc::Preprocessor> Preprocessor;
   mutable std::unique_ptr<tools::gcc::Compiler> Compiler;
   void findGccLibDir(const llvm::Triple &LiteralTriple);
Index: clang/lib/Driver/ToolChains/MinGW.cpp
===================================================================
--- clang/lib/Driver/ToolChains/MinGW.cpp
+++ clang/lib/Driver/ToolChains/MinGW.cpp
@@ -470,9 +470,16 @@
 
   Base += llvm::sys::path::get_separator();
   findGccLibDir(LiteralTriple);
+  TripleDirName = SubdirName;
   // GccLibDir must precede Base/lib so that the
   // correct crtbegin.o ,cetend.o would be found.
   getFilePaths().push_back(GccLibDir);
+
+  // openSUSE/Fedora
+  std::string CandidateSubdir = SubdirName + "/sys-root/mingw";
+  if (getDriver().getVFS().exists(Base + CandidateSubdir))
+    SubdirName = CandidateSubdir;
+
   getFilePaths().push_back(
       (Base + SubdirName + llvm::sys::path::get_separator() + "lib").str());
 
@@ -481,8 +488,6 @@
       (Base + SubdirName + llvm::sys::path::get_separator() + "mingw/lib").str());
 
   getFilePaths().push_back(Base + "lib");
-  // openSUSE
-  getFilePaths().push_back(Base + SubdirName + "/sys-root/mingw/lib");
 
   NativeLLVMSupport =
       Args.getLastArgValue(options::OPT_fuse_ld_EQ, CLANG_DEFAULT_LINKER)
@@ -636,12 +641,6 @@
   if (DriverArgs.hasArg(options::OPT_nostdlibinc))
     return;
 
-  if (GetRuntimeLibType(DriverArgs) == ToolChain::RLT_Libgcc) {
-    // openSUSE
-    addSystemInclude(DriverArgs, CC1Args,
-                     Base + SubdirName + "/sys-root/mingw/include");
-  }
-
   addSystemInclude(DriverArgs, CC1Args,
                    Base + SubdirName + llvm::sys::path::get_separator() +
                        "include");
@@ -719,7 +718,7 @@
     for (auto &CppIncludeBase : CppIncludeBases) {
       addSystemInclude(DriverArgs, CC1Args, CppIncludeBase);
       CppIncludeBase += Slash;
-      addSystemInclude(DriverArgs, CC1Args, CppIncludeBase + SubdirName);
+      addSystemInclude(DriverArgs, CC1Args, CppIncludeBase + TripleDirName);
       addSystemInclude(DriverArgs, CC1Args, CppIncludeBase + "backward");
     }
     break;


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