Eclipse luna with nuwen: Toolchain “MinGW GCC” is not detected

安装完最新版（luna）的eclipse cpp(或eclipse java with cdt plugin)和nuwen后，新建ｃ++ project并没有显示支持mingw toolchain. 打开属性有所提示“Toolchain “MinGW GCC” is not detected”。

而之前的一些eclipse版本是支持的，且没有任何特殊配置。

通过eclipse源码分析可知：新的eclipse由简单的check mingw的路径存在与否改变成check对应32版本的mingw32-gcc.exe和对应64版本的x86_64-w64-mingw32-gcc.exe，而nuwen安装之后存在的仅仅是gcc.exe，将此文件复制成对应的文件名即可呈现支持mingw toolchain.所以这个问题是由eclipse本身的代码改变所引起，与其他无关。

同时从源码可以看出，eclipse 32仅匹配mingw 32,而eclipse 64可以匹配mingw 32和mingw 64.

MinGW 定位的全部源码

新版本的eclipse源码：

	@Override
	public boolean isSupported(IToolChain toolChain, Version version, String instance) {
		IEnvironmentVariable var = new EnvironmentVariableManagerToolChain(toolChain).getVariable(ENV_PATH, true);
		String envPath = var != null ? var.getValue() : null;
		return MinGW.isAvailable(envPath);
	}


}

	/**
	 * Check if MinGW is available in the path.
	 *
	 * @param envPath - list of directories to search for MinGW separated
	 *    by path separator (format of environment variable $PATH)
	 *    or {@code null} to use current $PATH.
	 * @return {@code true} if MinGW is available, {@code false} otherwise.
	 */
	public static boolean isAvailable(String envPath) {
		return isWindowsPlatform && findMingwInPath(envPath) != null;
	}

	private static String findMingwInPath(String envPath) {
		if (envPath == null) {
			// $PATH from user preferences
			IEnvironmentVariable varPath = CCorePlugin.getDefault().getBuildEnvironmentManager().getVariable(ENV_PATH, null, true);
			if (varPath != null) {
				envPath = varPath.getValue();
			}
		}

		String mingwLocation = mingwLocationCache.get(envPath);
		// check if WeakHashMap contains the key as null may be the cached value
		if (mingwLocation == null && !mingwLocationCache.containsKey(envPath)) {
			// Check for MinGW-w64 on Windows 64 bit, see http://mingw-w64.sourceforge.net/
			if (Platform.ARCH_X86_64.equals(Platform.getOSArch())) {
				IPath gcc64Loc = PathUtil.findProgramLocation("x86_64-w64-mingw32-gcc.exe", envPath); //$NON-NLS-1$
				if (gcc64Loc != null) {
					mingwLocation  = gcc64Loc.removeLastSegments(2).toOSString();
				}
			}

			// Look for mingw32-gcc.exe
			if (mingwLocation == null) {
				IPath gccLoc = PathUtil.findProgramLocation("mingw32-gcc.exe", envPath); //$NON-NLS-1$
				if (gccLoc != null) {
					mingwLocation = gccLoc.removeLastSegments(2).toOSString();
				}
			}
			mingwLocationCache.put(envPath, mingwLocation);
		}

		return mingwLocation;
	}

旧版本eclipse代码：

public class MingwIsToolChainSupported implements IManagedIsToolChainSupported {
	@Override
	public boolean isSupported(IToolChain toolChain, Version version, String instance) {
		// Only supported if we can find the mingw bin dir to run the compiler
		return MingwEnvironmentVariableSupplier.getBinDir() != null;
	}