Fix for the compiler path in compile_commands.json file

Compiler path was wrongly created when anything was set on the "Prefix"
option from "Cross Settings". The code needs to check if anything is set
there before creating the default path for the compiler.

Author: alicetrifu

build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/core/jsoncdb/generator/CompilationDatabaseGenerator.java

@@ -229,10 +229,10 @@ private List<CompilationDatabaseInformation> populateObjList(IProject project, I
 						outputLocation + "", inputStrings, sourceLocation, outputLocation); //$NON-NLS-1$
 
 				IBuildMacroProvider provider = ManagedBuildManager.getBuildMacroProvider();
-				String compilerName = CompilationDatabaseGenerator.getCompilerName(tool);
+				String compilerName = CompilationDatabaseGenerator.getCompilerName(tool, config, cmdLInfo);
 				String commandLine = cmdLInfo.getCommandLine();
 				commandLine = commandLine.replace(compilerName, "").trim(); //$NON-NLS-1$
-				String compilerPath = findCompilerInPath(tool, config);
+				String compilerPath = findCompilerInPath(tool, config, cmdLInfo);
 				String resolvedOptionFileContents;
 				if (compilerPath != null && !compilerPath.isEmpty()) {
 					resolvedOptionFileContents = provider.resolveValueToMakefileFormat(compilerPath + " " + commandLine, //$NON-NLS-1$
@@ -438,11 +438,11 @@ public boolean visit(IResourceProxy proxy) throws CoreException {
 
 	}
 
-	private String findCompilerInPath(ITool tool, IConfiguration config) {
+	private String findCompilerInPath(ITool tool, IConfiguration config, IManagedCommandLineInfo cmdLInfo) {
 		if (toolMap.containsKey(tool)) {
 			return "\"" + toolMap.get(tool) + "\""; //$NON-NLS-1$//$NON-NLS-2$
 		}
-		String compilerName = CompilationDatabaseGenerator.getCompilerName(tool);
+		String compilerName = CompilationDatabaseGenerator.getCompilerName(tool, config, cmdLInfo);
 		File pathToCompiler = new File(compilerName);
 
 		if (pathToCompiler.isAbsolute()) {
@@ -469,9 +469,9 @@ private String findCompilerInPath(ITool tool, IConfiguration config) {
 		return null;
 	}
 
-	private static String getCompilerName(ITool tool) {
-		String compilerCommand = tool.getToolCommand();
-		String[] arguments = CommandLineUtil.argumentsToArray(compilerCommand);
+	private static String getCompilerName(ITool tool, IConfiguration config, IManagedCommandLineInfo cmdLInfo) {
+		String commandLine = cmdLInfo.getCommandLine();
+		String[] arguments = CommandLineUtil.argumentsToArray(commandLine);
 		if (arguments.length == 0) {
 			return ""; //$NON-NLS-1$
 		}