clang-tools: Improve wrapper script, add tests

pkgs/development/compilers/llvm/common/clang-tools/default.nix

@@ -1,6 +1,8 @@
 {
   lib,
   stdenv,
+  runCommand,
+  writeText,
   clang-unwrapped,
   clang,
   libcxxClang,
@@ -10,9 +12,7 @@
   enableLibcxx ? false,
 }:
 
-stdenv.mkDerivation {
-  unwrapped = clang-unwrapped;
-
+stdenv.mkDerivation (finalAttrs: {
   pname = "clang-tools";
   version = lib.getVersion clang-unwrapped;
   dontUnpack = true;
@@ -23,37 +23,69 @@ stdenv.mkDerivation {
 
     mkdir -p $out/bin
 
-    for tool in $unwrapped/bin/clang-*; do
-      tool=$(basename "$tool")
-
-      # Compilers have their own derivation, no need to include them here:
-      if [[ $tool == "clang-cl" || $tool == "clang-cpp" ]]; then
-        continue
-      fi
+    for toolPath in ${clang-unwrapped}/bin/clangd ${clang-unwrapped}/bin/clang-*; do
+      toolName=$(basename "$toolPath")
 
-      # Clang's derivation produces a lot of binaries, but the tools we are
-      # interested in follow the `clang-something` naming convention - except
-      # for clang-$version (e.g. clang-13), which is the compiler again:
-      if [[ ! $tool =~ ^clang\-[a-zA-Z_\-]+$ ]]; then
+      # Compilers have their own derivations, no need to include them here
+      if [[ $toolName == "clang-cl" || $toolName == "clang-cpp" || $toolName =~ ^clang\-[0-9]+$ ]]; then
         continue
       fi
 
-      ln -s $out/bin/clangd $out/bin/$tool
+      cp $toolPath $out/bin/$toolName-unwrapped
+      substituteAll ${./wrapper} $out/bin/$toolName
+      chmod +x $out/bin/$toolName
     done
 
-    if [[ -z "$(ls -A $out/bin)" ]]; then
-      echo "Found no binaries - maybe their location or naming convention changed?"
-      exit 1
-    fi
-
-    substituteAll ${./wrapper} $out/bin/clangd
-    chmod +x $out/bin/clangd
+    # clangd etc. find standard header files by looking at the directory the
+    # tool is located in and appending `../lib` to the search path. Since we
+    # are copying the binaries, they expect to find `$out/lib` present right
+    # within this derivation, containing `stddef.h` and so on.
+    #
+    # Note that using `ln -s` instead of `cp` in the loop above wouldn't avoid
+    # this problem, since it's `clang-unwrapped` which separates libs into a
+    # different output in the first place - here we are merely "merging" the
+    # directories back together, as expected by the tools.
+    ln -s ${clang-unwrapped.lib}/lib $out/lib
 
     runHook postInstall
   '';
 
+  passthru.tests.smokeOk =
+    let
+      src = writeText "main.cpp" ''
+        #include <iostream>
+
+        int main() {
+          std::cout << "Hi!";
+        }
+      '';
+
+    in
+    runCommand "clang-tools-test-smoke-ok" { } ''
+      ${finalAttrs.finalPackage}/bin/clangd  --check=${src}
+      touch $out
+    '';
+
+  passthru.tests.smokeErr =
+    let
+      src = writeText "main.cpp" ''
+        #include <iostream>
+
+        int main() {
+           std::cout << "Hi!";
+        }
+      '';
+
+    in
+    runCommand "clang-tools-test-smoke-err" { } ''
+      (${finalAttrs.finalPackage}/bin/clangd --query-driver='**' --check=${src} 2>&1 || true) \
+          | grep 'use of undeclared identifier'
+
+      touch $out
+    '';
+
   meta = llvm_meta // {
     description = "Standalone command line tools for C++ development";
     maintainers = with lib.maintainers; [ patryk27 ];
   };
-}
+})

pkgs/development/compilers/llvm/common/clang-tools/wrapper

@@ -18,10 +18,23 @@ buildcpath() {
   echo $path${after:+':'}$after
 }
 
-export CPATH=${CPATH}${CPATH:+':'}$(buildcpath ${NIX_CFLAGS_COMPILE} \
-                                               $(<@clang@/nix-support/libc-cflags)):@clang@/resource-root/include
-export CPLUS_INCLUDE_PATH=${CPLUS_INCLUDE_PATH}${CPLUS_INCLUDE_PATH:+':'}$(buildcpath ${NIX_CFLAGS_COMPILE} \
-                                                                                      $(<@clang@/nix-support/libcxx-cxxflags) \
-                                                                                      $(<@clang@/nix-support/libc-cflags)):@clang@/resource-root/include
+# When user passes `--query-driver`, avoid extending `CPATH` et al, since we
+# don't want to infect user-specified toolchain and headers with our stuff.
+extendcpath=true
 
-exec -a "$0" @unwrapped@/bin/$(basename $0) "$@"
+for arg in "$@"; do
+  if [[ "${arg}" == \-\-query\-driver* ]]; then
+    extendcpath=false
+  fi
+done
+
+if [ "$extendcpath" = true ]; then
+  export CPATH=${CPATH}${CPATH:+':'}$(buildcpath ${NIX_CFLAGS_COMPILE} \
+                                                 $(<@clang@/nix-support/libc-cflags))
+
+  export CPLUS_INCLUDE_PATH=${CPLUS_INCLUDE_PATH}${CPLUS_INCLUDE_PATH:+':'}$(buildcpath ${NIX_CFLAGS_COMPILE} \
+                                                                                        $(<@clang@/nix-support/libcxx-cxxflags) \
+                                                                                        $(<@clang@/nix-support/libc-cflags))
+fi
+
+@out@/bin/$(basename $0)-unwrapped "$@"