Fix RoboRIO Cross-Toolchain GCC Status (#405)

* Dedicated RoboRIO Toolchain, allow Toolchain Path to change

* Add cCompiler Tool to correctly discover RoboRIO GCC on Mac

* Add @333fred requests for GString and ToolChainPath

* Add Toolchain Path option to README

README.md

@@ -47,6 +47,12 @@ To build a specific subproject, such as WPILibC, you must access the subproject
 ./gradlew :wpilibc:build
 ```
 
+If you have installed the FRC Toolchain to a directory other than the default, or if the Toolchain location is not on your System PATH, you can pass the `toolChainPath` property to specify where it is located. Example:
+
+```bash
+./gradlew build -PtoolChainPath=some/path/to/frc/toolchain/bin
+```
+
 If you also want simulation to be built, add -PmakeSim. This requires gazebo_transport. We have tested on 14.04 and 15.05, but any correct install of Gazebo should work, even on Windows if you build Gazebo from source. Correct means CMake needs to be able to find gazebo-config.cmake. See [The Gazebo website](https://gazebosim.org/) for installation instructions.
 
 ```bash

cppSettings.gradle

@@ -72,6 +72,10 @@ task clean(type: Delete) {
     delete buildDir
 }
 
+if (!hasProperty("toolChainPath")) {
+    ext.toolChainPath = null
+}
+
 subprojects {
     ext.defineWpiUtilProperties = {
         ext.wpiUtil = wpiUtilUnzipLocation
@@ -165,8 +169,11 @@ subprojects {
             }
             // Adds a custom toolchain for our compiler prefix and options
             toolChains {
-                gcc(Gcc) {
-                    target('arm') {
+                roborioGcc(Gcc) {
+                    if (toolChainPath != null)
+                        path toolChainPath
+                    target('roborio-arm') {
+                        cCompiler.executable = compilerPrefix + cCompiler.executable
                         cppCompiler.executable = compilerPrefix + cppCompiler.executable
                         linker.executable = compilerPrefix + linker.executable
                         assembler.executable = compilerPrefix + assembler.executable
@@ -188,37 +195,10 @@ subprojects {
                         staticLibArchiver.executable = compilerPrefix + staticLibArchiver.executable
                     }
                 }
-                // Workaround for OS X. Macs for some reason want to use Xcode's gcc
-                // (which just wraps Clang), so we have to explicitly make it so
-                // that trying to compile with Clang will call gcc instead
-                macGcc(Clang) {
-                    target('arm') {
-                        cppCompiler.executable = compilerPrefix + 'g++'
-                        linker.executable = compilerPrefix + 'g++'
-                        assembler.executable = compilerPrefix + 'gcc'
-                        // Gradle auto-adds the -m32 argument to the linker and compiler. Our compiler only supports
-                        // arm, and doesn't understand this flag, so it is removed from both
-                        cppCompiler.withArguments { args ->
-                            args << '-std=c++1y' << '-Wformat=2' << '-Wall' << '-Wextra' << '-Werror' << '-pedantic'
-                            args << '-Wno-psabi' << '-Wno-unused-parameter' << '-fPIC' << '-Og' << '-g3' << '-rdynamic'
-                            //TODO: When the compiler allows us to actually call deprecated functions from within
-                            // deprecated function, remove this line (this will cause calling deprecated functions
-                            // to be treated as a warning rather than an error).
-                            args << '-Wno-error=deprecated-declarations'
-                            args.remove('-m32')
-                        }
-                        linker.withArguments { args ->
-                            args << '-rdynamic'
-                            args.remove('-m32')
-                        }
-                        staticLibArchiver.executable = compilerPrefix + 'ar'
-                    }
-                }
             }
 
-            // The only platform is arm linux
             platforms {
-                arm {
+                'roborio-arm' {
                     architecture 'arm'
                     operatingSystem 'linux'
                 }
@@ -228,6 +208,11 @@ subprojects {
         ext.niLibraryHeadersRoot = "${rootDir}/ni-libraries/include"
         ext.niLibraryHeadersChipObject = "${rootDir}/ni-libraries/include/FRC_FPGA_ChipObject"
 
+        ext.binTool = { tool ->
+            if (toolChainPath != null) return "${toolChainPath}/${compilerPrefix}${tool}"
+            return "${compilerPrefix}${tool}"
+        }
+
         // This task adds the appropriate linker flags for the NI libraries
         ext.addNiLibraryLinks = { linker, targetPlatform ->
             String architecture = targetPlatform.architecture
@@ -246,9 +231,9 @@ subprojects {
                         def library = task.outputFile.absolutePath
                         def debugLibrary = task.outputFile.absolutePath + ".debug"
                         task.doLast {
-                            exec { commandLine "${compilerPrefix}objcopy", '--only-keep-debug', library, debugLibrary }
-                            exec { commandLine "${compilerPrefix}strip", '-g', library }
-                            exec { commandLine "${compilerPrefix}objcopy", "--add-gnu-debuglink=$debugLibrary", library }
+                            exec { commandLine binTool('objcopy'), '--only-keep-debug', library, debugLibrary }
+                            exec { commandLine binTool('strip'), '-g', library }
+                            exec { commandLine binTool('objcopy'), "--add-gnu-debuglink=$debugLibrary", library }
                         }
                     }
                 }

hal/build.gradle

@@ -14,7 +14,7 @@ debugStripSetup(project)
 model {
     components {
         HALAthena(NativeLibrarySpec) {
-            targetPlatform 'arm'
+            targetPlatform 'roborio-arm'
             binaries.all {
                 tasks.withType(CppCompile) {
                     addNiLibraryLinks(linker, targetPlatform)

myRobotCpp/build.gradle

@@ -10,7 +10,7 @@ ext.hal = project(':hal').projectDir.getAbsolutePath()
 model {
     components {
         myRobotcpp(NativeExecutableSpec) {
-            targetPlatform 'arm'
+            targetPlatform 'roborio-arm'
             binaries.all {
                 tasks.withType(CppCompile) {
                     addNiLibraryLinks(linker, targetPlatform)

wpilibc/athena.gradle

@@ -9,7 +9,7 @@ def ntSourceDir = "$buildDir/ntSources"
 model {
     components {
         wpilibc(NativeLibrarySpec) {
-            targetPlatform 'arm'
+            targetPlatform 'roborio-arm'
             binaries.all {
                 tasks.withType(CppCompile) {
                     dependsOn generateCppVersion

wpilibcIntegrationTests/build.gradle

@@ -11,7 +11,7 @@ ext.hal = project(':hal').projectDir.getAbsolutePath()
 model {
     components {
         FRCUserProgram(NativeExecutableSpec) {
-            targetPlatform 'arm'
+            targetPlatform 'roborio-arm'
             binaries.all {
                 tasks.withType(CppCompile) {
                     cppCompiler.args "-DNAMESPACED_WPILIB"

wpilibj/athena.gradle

@@ -30,7 +30,7 @@ defineWpiUtilProperties()
 model {
     components {
         wpilibJavaJNI(NativeLibrarySpec) {
-            targetPlatform 'arm'
+            targetPlatform 'roborio-arm'
             binaries.all {
                 tasks.withType(CppCompile) {
                     dependsOn jniHeaders
@@ -197,7 +197,7 @@ task checkJNISymbols() {
     doLast {
         defineCrossCompilerProperties()
         exec {
-            commandLine "${compilerPrefix}nm", lib
+            commandLine binTool('nm'), lib
             standardOutput = nmOutput
         }
         // Remove '\r' so we can check for full string contents