clang15/0002-clang-MinGW-Improve-detection-of-libstdc-headers-on-.patch

From d3b79c2950d590cb272648f1c6a9dd7646f57beb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
Date: Tue, 22 Nov 2022 14:39:39 +0200
Subject: [PATCH 2/2] [clang] [MinGW] Improve detection of libstdc++ headers on
 Fedora

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). 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.

Differential Revision: https://reviews.llvm.org/D138693
---
 clang/lib/Driver/ToolChains/MinGW.cpp | 19 +++++++++----------
 clang/lib/Driver/ToolChains/MinGW.h   |  1 +
 clang/test/Driver/mingw.cpp           |  5 ++++-
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/MinGW.cpp b/clang/lib/Driver/ToolChains/MinGW.cpp
index 0ebacea6e87f..2a9bf4b18f19 100644
--- a/clang/lib/Driver/ToolChains/MinGW.cpp
+++ b/clang/lib/Driver/ToolChains/MinGW.cpp
@@ -376,7 +376,7 @@ void toolchains::MinGW::findGccLibDir(const llvm::Triple &LiteralTriple) {
   SubdirNames.back() += "-w64-mingw32ucrt";
   SubdirNames.emplace_back("mingw32");
   if (SubdirName.empty()) {
-    SubdirName = getTriple().getArchName();
+    SubdirName = getTriple().getArchName().str();
     SubdirName += "-w64-mingw32";
   }
   // lib: Arch Linux, Ubuntu, Windows
@@ -459,9 +459,16 @@ toolchains::MinGW::MinGW(const Driver &D, const llvm::Triple &Triple,
 
   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());
 
@@ -470,8 +477,6 @@ toolchains::MinGW::MinGW(const Driver &D, const llvm::Triple &Triple,
       (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)
@@ -621,12 +626,6 @@ void toolchains::MinGW::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   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");
@@ -684,7 +683,7 @@ void toolchains::MinGW::AddClangCXXStdlibIncludeArgs(
     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;
diff --git a/clang/lib/Driver/ToolChains/MinGW.h b/clang/lib/Driver/ToolChains/MinGW.h
index bc17d273e776..ef9bfb29e175 100644
--- a/clang/lib/Driver/ToolChains/MinGW.h
+++ b/clang/lib/Driver/ToolChains/MinGW.h
@@ -106,6 +106,7 @@ private:
   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);
diff --git a/clang/test/Driver/mingw.cpp b/clang/test/Driver/mingw.cpp
index bde952fb3565..46ea55b9500d 100644
--- a/clang/test/Driver/mingw.cpp
+++ b/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
-- 
2.38.1