gnu: Add llvm-16.

* gnu/packages/llvm.scm (llvm-16): New variable.
* gnu/packages/patches/clang-16.0-libc-search-path.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.

Change-Id: I27738152ca95aeeef8d8b7150fdf14825b6b0b4d

gnu/local.mk

@@ -1016,6 +1016,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/clang-13.0-libc-search-path.patch	\
   %D%/packages/patches/clang-14.0-libc-search-path.patch	\
   %D%/packages/patches/clang-15.0-libc-search-path.patch	\
+  %D%/packages/patches/clang-16.0-libc-search-path.patch	\
   %D%/packages/patches/clang-runtime-asan-build-fixes.patch	\
   %D%/packages/patches/clang-runtime-esan-build-fixes.patch	\
   %D%/packages/patches/clang-runtime-9-libsanitizer-mode-field.patch	\

gnu/packages/llvm.scm

@@ -590,11 +590,13 @@ output), and Binutils.")
 
 (define %llvm-monorepo-hashes
   '(("14.0.6" . "14f8nlvnmdkp9a9a79wv67jbmafvabczhah8rwnqrgd5g3hfxxxx")
-    ("15.0.7" . "12sggw15sxq1krh1mfk3c1f07h895jlxbcifpwk3pznh4m1rjfy2")))
+    ("15.0.7" . "12sggw15sxq1krh1mfk3c1f07h895jlxbcifpwk3pznh4m1rjfy2")
+    ("16.0.6" . "0jxmapg7shwkl88m4mqgfjv4ziqdmnppxhjz6vz51ycp2x4nmjky")))
 
 (define %llvm-patches
   '(("14.0.6" . ("clang-14.0-libc-search-path.patch"))
-    ("15.0.7" . ("clang-15.0-libc-search-path.patch"))))
+    ("15.0.7" . ("clang-15.0-libc-search-path.patch"))
+    ("16.0.6" . ("clang-16.0-libc-search-path.patch"))))
 
 (define (llvm-monorepo version)
   (origin
@@ -1450,6 +1452,12 @@ Library.")
                    #:legacy-build-shared-libs? #t
                    #:patches '("clang-3.5-libc-search-path.patch")))
 
+(define-public llvm-16
+  (package
+    (inherit llvm-15)
+    (version "16.0.6")
+    (source (llvm-monorepo version))))
+
 ;; Default LLVM and Clang version.
 (define-public libomp libomp-13)
 (define-public llvm llvm-13)

gnu/packages/patches/clang-16.0-libc-search-path.patch

@@ -0,0 +1,95 @@
+Clang attempts to guess file names based on the OS and distro (yes!),
+but unfortunately, that doesn't work for us.
+
+This patch makes it easy to insert libc's $libdir so that Clang passes the
+correct absolute file name of crt1.o etc. to 'ld'.  It also disables all
+the distro-specific stuff and removes the hard-coded FHS directory names
+to make sure Clang also works on foreign distros.
+
+diff --git a/clang/lib/Driver/Distro.cpp b/clang/lib/Driver/Distro.cpp
+index 87a0c5a58511..86ea82eda4b5 100644
+--- a/clang/lib/Driver/Distro.cpp
++++ b/clang/lib/Driver/Distro.cpp
+@@ -98,6 +98,10 @@ static Distro::DistroType DetectLsbRelease(llvm::vfs::FileSystem &VFS) {
+ }
+ 
+ static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS) {
++  // The compiler should always behave the same, even when used via Guix on a
++  // foreign distro.
++  return Distro::UnknownDistro;
++
+   Distro::DistroType Version = Distro::UnknownDistro;
+ 
+   // Newer freedesktop.org's compilant systemd-based systems
+diff --git a/clang/lib/Driver/ToolChains/Cuda.cpp b/clang/lib/Driver/ToolChains/Cuda.cpp
+index aa125bb308e8..8b86e144054c 100644
+--- a/clang/lib/Driver/ToolChains/Cuda.cpp
++++ b/clang/lib/Driver/ToolChains/Cuda.cpp
+@@ -124,6 +124,9 @@ CudaInstallationDetector::CudaInstallationDetector(
+     const Driver &D, const llvm::Triple &HostTriple,
+     const llvm::opt::ArgList &Args)
+     : D(D) {
++  // Don't look for CUDA in /usr.
++  return;
++
+   struct Candidate {
+     std::string Path;
+     bool StrictChecking;
+diff --git a/clang/lib/Driver/ToolChains/Linux.cpp b/clang/lib/Driver/ToolChains/Linux.cpp
+index c6fb290ffdb4..4736f4bb3392 100644
+--- a/clang/lib/Driver/ToolChains/Linux.cpp
++++ b/clang/lib/Driver/ToolChains/Linux.cpp
+@@ -189,6 +189,10 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+ 
+   Generic_GCC::PushPPaths(PPaths);
+ 
++  // Comment out the distro-specific tweaks so that they don't bite when
++  // using Guix on a foreign distro.
++#if 0
++
+   Distro Distro(D.getVFS(), Triple);
+ 
+   if (Distro.IsAlpineLinux() || Triple.isAndroid()) {
+@@ -249,6 +253,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+ 
+ #ifdef ENABLE_LINKER_BUILD_ID
+   ExtraOpts.push_back("--build-id");
++#endif
+ #endif
+ 
+   // The selection of paths to try here is designed to match the patterns which
+@@ -270,6 +275,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+   }
+   Generic_GCC::AddMultilibPaths(D, SysRoot, OSLibDir, MultiarchTriple, Paths);
+ 
++#if 0
+   addPathIfExists(D, concat(SysRoot, "/lib", MultiarchTriple), Paths);
+   addPathIfExists(D, concat(SysRoot, "/lib/..", OSLibDir), Paths);
+ 
+@@ -298,9 +304,11 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+     addPathIfExists(D, concat(SysRoot, "/", OSLibDir, ABIName), Paths);
+     addPathIfExists(D, concat(SysRoot, "/usr", OSLibDir, ABIName), Paths);
+   }
++#endif
+ 
+   Generic_GCC::AddMultiarchPaths(D, SysRoot, OSLibDir, Paths);
+ 
++#if 0
+   // The deprecated -DLLVM_ENABLE_PROJECTS=libcxx configuration installs
+   // libc++.so in D.Dir+"/../lib/". Detect this path.
+   // TODO Remove once LLVM_ENABLE_PROJECTS=libcxx is unsupported.
+@@ -310,6 +318,14 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+ 
+   addPathIfExists(D, concat(SysRoot, "/lib"), Paths);
+   addPathIfExists(D, concat(SysRoot, "/usr/lib"), Paths);
++#endif
++
++  // Add libc's lib/ directory to the search path, so that crt1.o, crti.o,
++  // and friends can be found.
++  addPathIfExists(D, "@GLIBC_LIBDIR@", Paths);
++
++  // Add GCC's lib/ directory so libstdc++.so can be found.
++  addPathIfExists(D, GCCInstallation.getParentLibPath(), Paths);
+ }
+ 
+ ToolChain::RuntimeLibType Linux::GetDefaultRuntimeLibType() const {