gnu: llvm: Add 10.0.0.

* gnu/packages/llvm.scm (llvm-10, clang-runtime-10, clang-10)
(clang-toolchain-10, llvm-9, clang-runtime-9, clang-9)
(clang-toolchain-9): New variables.
(llvm, clang, clang-runtime, clang-toolchain): Redefine as aliases to
the '-9' bindings.
* gnu/packages/patches/clang-10.0-libc-search-path.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu/local.mk

@@ -805,6 +805,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/clang-6.0-libc-search-path.patch		\
   %D%/packages/patches/clang-7.0-libc-search-path.patch		\
   %D%/packages/patches/clang-9.0-libc-search-path.patch		\
+  %D%/packages/patches/clang-10.0-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/classpath-aarch64-support.patch		\

gnu/packages/llvm.scm

@@ -1,7 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2014, 2016, 2018 Eric Bavier <bavier@member.fsf.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
-;;; Copyright © 2015, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2016 Dennis Mungai <dmngaie@gmail.com>
 ;;; Copyright © 2016, 2018, 2019, 2020 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2017 Roel Janssen <roel@gnu.org>
@@ -84,17 +84,17 @@ as \"x86_64-linux\"."
       (string-append "https://releases.llvm.org/" version "/" component "-"
                      version ".src.tar.xz")))
 
-(define-public llvm
+(define-public llvm-10
   (package
     (name "llvm")
-    (version "9.0.1")
+    (version "10.0.0")
     (source
      (origin
       (method url-fetch)
       (uri (llvm-download-uri "llvm" version))
       (sha256
        (base32
-        "16hwp3qa54c3a3v7h8nlw0fh5criqh0hlr1skybyk0cz70gyx880"))))
+        "1pwgm6cr0xr5a0hrbqs1zvsvvjvy0yq1y47c96804wcs795s90yz"))))
     (build-system cmake-build-system)
     (native-inputs
      `(("python" ,python-2) ;bytes->str conversion in clang>=3.7 needs python-2
@@ -368,23 +368,49 @@ output), and Binutils.")
               ("libc-debug" ,glibc "debug")
               ("libc-static" ,glibc "static")))))
 
-(define-public clang-runtime
+(define-public clang-runtime-10
   (clang-runtime-from-llvm
-   llvm
+   llvm-10
+   "0x9c531k6ww21s2mkdwqx1vbdjmx6d4wmfb8gdbj0wqa796sczba"))
+
+(define-public clang-10
+  (clang-from-llvm llvm-10 clang-runtime-10
+                   "08fbxa2a0kr3ni35ckppj0kyvlcyaywrhpqwcdrdy0z900mhcnw8"
+                   #:patches '("clang-10.0-libc-search-path.patch")))
+
+(define-public clang-toolchain-10
+  (make-clang-toolchain clang-10))
+
+(define-public llvm-9
+  (package
+    (inherit llvm-10)
+    (version "9.0.1")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (llvm-download-uri "llvm" version))
+       (sha256
+        (base32
+         "16hwp3qa54c3a3v7h8nlw0fh5criqh0hlr1skybyk0cz70gyx880"))))))
+
+(define-public clang-runtime-9
+  (clang-runtime-from-llvm
+   llvm-9
    "0xwh79g3zggdabxgnd0bphry75asm1qz7mv3hcqihqwqr6aspgy2"))
 
-(define-public clang
-  (clang-from-llvm llvm clang-runtime
+(define-public clang-9
+  (clang-from-llvm llvm-9 clang-runtime-9
                    "0ls2h3iv4finqyflyhry21qhc9cm9ga7g1zq21020p065qmm2y2p"
                    #:patches '("clang-9.0-libc-search-path.patch")))
 
-(define-public clang-toolchain
-  (make-clang-toolchain clang))
+(define-public clang-toolchain-9
+  (make-clang-toolchain clang-9))
 
-(define-public llvm-9 llvm)
-(define-public clang-runtime-9 clang-runtime)
-(define-public clang-9 clang)
-(define-public clang-toolchain-9 clang-toolchain)
+;; Default LLVM and Clang version.
+(define-public llvm llvm-9)
+(define-public clang-runtime clang-runtime-9)
+(define-public clang clang-9)
+(define-public clang-toolchain clang-toolchain-9)
 
 (define-public llvm-8
   (package

gnu/packages/patches/clang-10.0-libc-search-path.patch

@@ -0,0 +1,84 @@
+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 non-Guix systems.
+
+diff --git a/lib/Driver/ToolChains/Linux.cpp b/lib/Driver/ToolChains/Linux.cpp
+index bff1ab10..79e1477e 100644
+--- a/lib/Driver/ToolChains/Linux.cpp
++++ b/lib/Driver/ToolChains/Linux.cpp
+@@ -240,6 +240,9 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+                          .str());
+   }
+ 
++// 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()) {
+@@ -306,6 +309,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+ 
+   if (IsAndroid || Distro.IsOpenSUSE())
+     ExtraOpts.push_back("--enable-new-dtags");
++#endif	// Guix
+ 
+   // The selection of paths to try here is designed to match the patterns which
+   // the GCC driver itself uses, as this is part of the GCC-compatible driver.
+@@ -363,7 +367,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+     // the cross. Note that GCC does include some of these directories in some
+     // configurations but this seems somewhere between questionable and simply
+     // a bug.
+-    if (StringRef(LibPath).startswith(SysRoot)) {
++    if (0) {
+       addPathIfExists(D, LibPath + "/" + MultiarchTriple, Paths);
+       addPathIfExists(D, LibPath + "/../" + OSLibDir, Paths);
+     }
+@@ -382,6 +386,8 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+   addPathIfExists(D, SysRoot + "/lib/" + MultiarchTriple, Paths);
+   addPathIfExists(D, SysRoot + "/lib/../" + OSLibDir, Paths);
+ 
++// This requires the commented distro tweaks above.
++#if 0
+   if (IsAndroid) {
+     // Android sysroots contain a library directory for each supported OS
+     // version as well as some unversioned libraries in the usual multiarch
+@@ -410,10 +416,15 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+     addPathIfExists(D, SysRoot + "/" + OSLibDir + "/" + ABIName, Paths);
+     addPathIfExists(D, SysRoot + "/usr/" + OSLibDir + "/" + ABIName, Paths);
+   }
++#endif
+ 
+   // Try walking via the GCC triple path in case of biarch or multiarch GCC
+   // installations with strange symlinks.
+   if (GCCInstallation.isValid()) {
++
++// The following code would end up adding things like
++// "/usr/lib/x86_64-unknown-linux-gnu/../../lib64" to the search path.
++#if 0
+     addPathIfExists(D,
+                     SysRoot + "/usr/lib/" + GCCInstallation.getTriple().str() +
+                         "/../../" + OSLibDir,
+@@ -426,6 +437,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+                              BiarchSibling.gccSuffix(),
+                       Paths);
+     }
++#endif
+ 
+     // See comments above on the multilib variant for details of why this is
+     // included even from outside the sysroot.
+@@ -450,8 +462,9 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+   if (StringRef(D.Dir).startswith(SysRoot))
+     addPathIfExists(D, D.Dir + "/../lib", Paths);
+ 
+-  addPathIfExists(D, SysRoot + "/lib", Paths);
+-  addPathIfExists(D, SysRoot + "/usr/lib", Paths);
++  // 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);
+ }
+ 
+ ToolChain::CXXStdlibType Linux::GetDefaultCXXStdlibType() const {