build: simplify clang(++) configuration

also introduce 'execClang' block

InteropExample/build.gradle

@@ -20,7 +20,7 @@ kotlinNativeInterop {
     llvm {
         defFile '../backend.native/llvm.def'
         compilerOpts "-I$llvmDir/include"
-        linkerOpts "-L$llvmDir/lib", "-B$sysrootDir/usr/bin"
+        linkerOpts "-L$llvmDir/lib"
     }
 
 }

backend.native/build.gradle

@@ -105,20 +105,19 @@ String[] linkerOpts1() {
              + ["-L$libffiDir/lib", "-lffi"])
     ArrayList<String> strldflags = new ArrayList<>()
     ldflags.forEach{strldflags.add(it.toString())}
-    strldflags.add("-B$sysrootDir/usr/bin".toString())
     return strldflags.toArray(new String[0])
 }
 
 kotlinNativeInterop {
    llvm {
      defFile 'llvm.def'
-     compilerOpts "-fPIC", "-I$llvmDir/include", "-B$sysrootDir/usr/bin"
+     compilerOpts "-fPIC", "-I$llvmDir/include"
      linkerOpts linkerOpts1()
    }
 
    hash { // TODO: copy-pasted from ':common:compileHash'
      compilerOpts '-fPIC'
-     linkerOpts '-fPIC', "-B$sysrootDir/usr/bin"
+     linkerOpts '-fPIC'
      linker 'clang++'
      linkOutputs ':common:compileHash'
 

backend.native/tests/build.gradle

@@ -11,8 +11,6 @@ abstract class KonanTest extends DefaultTask {
     def backendNative = project.project(":backend.native")
     def runtimeProject = project.project(":runtime")
     def llvmLlc = llvmTool("llc")
-    def llvmC = llvmTool("clang")
-    def llvmCAdditionalArgs = ["--sysroot=$project.sysrootDir"]
     def runtimeBc = new File("${runtimeProject.buildDir.canonicalPath}/runtime.bc")
     def mainC = 'main.c'
     String goldValue = null
@@ -100,22 +98,18 @@ abstract class KonanTest extends DefaultTask {
 class UnitKonanTest extends KonanTest {
     void compileTest(File sourceS, File runtimeS, File exe) {
         def testC = sourceS.absolutePath.replace(".kt.S", "-test.c")
-        project.exec {
-            commandLine "${llvmC}", "-B${project.sysrootDir}/usr/bin", "${testC}", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
+        project.execClang {
+            commandLine "clang", "${testC}", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
                     "-o", "${exe.absolutePath}"
-
-            args llvmCAdditionalArgs
         }
     }
 }
 
 class RunKonanTest extends KonanTest {
     void compileTest(File sourceS, File runtimeS, File exe) {
-        project.exec {
-            commandLine "${llvmC}", "-DRUN_TEST", "-B${project.sysrootDir}/usr/bin", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
+        project.execClang {
+            commandLine "clang", "-DRUN_TEST", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
                     "-o", "${exe.absolutePath}"
-
-            args llvmCAdditionalArgs
         }
     }
 }

build.gradle

@@ -11,15 +11,22 @@ allprojects {
         evaluationDependsOn(":dependencies")
     }
 
+    ext.clangArgs = ["--sysroot=$sysrootDir", "-B$sysrootDir/usr/bin"]
+    ext.clangPath = ["$llvmDir/bin"]
+
+    convention.plugins.execClang = new org.jetbrains.kotlin.ExecClang(project)
+
     plugins.withType(NativeComponentPlugin) {
         model {
             toolChains {
                 clang(Clang) {
-                    path "$llvmDir/bin"
+                    clangPath.each {
+                        path it
+                    }
+
                     eachPlatform { // TODO: will not work when cross-compiling
                         [cCompiler, cppCompiler, linker].each {
-                            it.withArguments { it << "--sysroot=$sysrootDir"}
-                            it.withArguments { it << "-B$sysrootDir/usr/bin"}
+                            it.withArguments { it.addAll(clangArgs) }
                         }
 
                     }

buildSrc/src/main/groovy/org/jetbrains/kotlin/CompileToBitcode.groovy

@@ -68,13 +68,11 @@ class CompileCppToBitcode extends DefaultTask {
         File objDir = this.getObjDir()
         objDir.mkdirs()
 
-        project.exec {
+        project.execClang {
             workingDir objDir
-            executable "$project.llvmDir/bin/clang++"
+            executable "clang++"
             args '-std=c++11'
 
-            args "--sysroot=$project.sysrootDir"
-
             args compilerArgs
 
             args "-I$headersDir"

buildSrc/src/main/groovy/org/jetbrains/kotlin/ExecClang.groovy

@@ -0,0 +1,50 @@
+package org.jetbrains.kotlin
+
+import org.gradle.api.Action
+import org.gradle.api.GradleException
+import org.gradle.api.Project
+import org.gradle.process.ExecResult
+import org.gradle.process.ExecSpec
+import org.gradle.util.ConfigureUtil
+
+class ExecClang {
+
+    private final Project project
+
+    ExecClang(Project project) {
+        this.project = project
+    }
+
+    public ExecResult execClang(Closure closure) {
+        return this.execClang(ConfigureUtil.configureUsing(closure));
+    }
+
+    public ExecResult execClang(Action<? super ExecSpec> action) {
+        Action<? super ExecSpec> extendedAction = new Action<ExecSpec>() {
+            @Override
+            void execute(ExecSpec execSpec) {
+                action.execute(execSpec)
+
+                execSpec.with {
+
+                    if (executable == null) {
+                        executable = 'clang'
+                    }
+
+                    if (executable in ['clang', 'clang++']) {
+                        executable = "${project.llvmDir}/bin/$executable"
+                    } else {
+                        throw new GradleException("unsupport clang executable: $executable")
+                    }
+
+                    environment["PATH"] = project.files(project.clangPath).asPath +
+                            File.pathSeparator + environment["PATH"]
+
+                    args project.clangArgs
+                }
+
+            }
+        }
+        return project.exec(extendedAction)
+    }
+}

buildSrc/src/main/groovy/org/jetbrains/kotlin/NativeInteropPlugin.groovy

@@ -174,9 +174,12 @@ class NamedNativeInteropConfig implements Named {
                     args "-linker:" + linker
                 }
 
-                String sysrootArg = "--sysroot=$project.sysrootDir"
-                compilerOpts += sysrootArg
-                linkerOpts   += sysrootArg
+                // TODO: the interop plugin should probably be reworked to execute clang from build scripts directly
+                environment['PATH'] = project.files(project.clangPath).asPath +
+                        File.pathSeparator + environment['PATH']
+
+                compilerOpts += project.clangArgs
+                linkerOpts   += project.clangArgs
 
                 args compilerOpts.collect { "-copt:$it" }
                 args linkerOpts.collect { "-lopt:$it" }