Utils: Introduce a FilePath::withNewPath() convenience method

It's effectively the mirrored version of onDevice() with an
equally odd name which is a bit more straightforward to use
in some cases.

Change-Id: I0cfedeb58871a857c93144e2a0d734bad1bcd887
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/utils/fileutils.cpp

@@ -1384,6 +1384,26 @@ FilePath FilePath::onDevice(const FilePath &deviceTemplate) const
     return res;
 }
 
+/*!
+    Returns a FilePath with local path \a newPath on the same device
+    as the current object.
+
+    Example usage:
+    \code
+        devicePath = FilePath::fromString("docker://123/tmp");
+        newPath = devicePath.withNewPath("/bin/ls");
+        assert(realDir == FilePath::fromUrl("docker://123/bin/ls"))
+    \endcode
+*/
+FilePath FilePath::withNewPath(const QString &newPath) const
+{
+    FilePath res;
+    res.m_data = newPath;
+    res.m_host = m_host;
+    res.m_scheme = m_scheme;
+    return res;
+}
+
 /*!
     Searched a binary corresponding to this object in the PATH of
     the device implied by this object's scheme and host.

src/libs/utils/fileutils.h

@@ -113,6 +113,7 @@ public:
 
     QString toString() const;
     FilePath onDevice(const FilePath &deviceTemplate) const;
+    FilePath withNewPath(const QString &newPath) const;
 
     QFileInfo toFileInfo() const;
     QVariant toVariant() const;

src/plugins/cmakeprojectmanager/cmaketoolmanager.cpp

@@ -185,7 +185,7 @@ void CMakeToolManager::autoDetectCMakeForDevice(const FilePath &deviceRoot,
                                                 QString *logMessage)
 {
     QStringList messages{tr("Searching CMake binaries...")};
-    const FilePaths candidates = {FilePath::fromString("cmake").onDevice(deviceRoot)};
+    const FilePaths candidates = {deviceRoot.withNewPath("cmake")};
     const Environment env = deviceRoot.deviceEnvironment();
     for (const FilePath &candidate : candidates) {
         const FilePath cmake = candidate.searchOnDevice(env.path());

src/plugins/projectexplorer/gcctoolchain.cpp

@@ -238,13 +238,13 @@ static QString gccVersion(const FilePath &path,
     return QString::fromLocal8Bit(runGcc(path, arguments, env)).trimmed();
 }
 
-static FilePath gccInstallDir(const FilePath &path,
+static FilePath gccInstallDir(const FilePath &compiler,
                               const Environment &env,
                               const QStringList &extraArgs = {})
 {
     QStringList arguments = extraArgs;
     arguments << "-print-search-dirs";
-    QString output = QString::fromLocal8Bit(runGcc(path, arguments, env)).trimmed();
+    QString output = QString::fromLocal8Bit(runGcc(compiler, arguments, env)).trimmed();
     // Expected output looks like this:
     //   install: /usr/lib/gcc/x86_64-linux-gnu/7/
     //   ...
@@ -255,7 +255,7 @@ static FilePath gccInstallDir(const FilePath &path,
     const QString line = QTextStream(&output).readLine();
     if (!line.startsWith(prefix))
         return {};
-    return FilePath::fromString(QDir::cleanPath(line.mid(prefix.size()))).onDevice(path);
+    return compiler.withNewPath(QDir::cleanPath(line.mid(prefix.size())));
 }
 
 // --------------------------------------------------------------------------

src/plugins/webassembly/webassemblyemsdk.cpp

@@ -60,8 +60,7 @@ static QString emSdkEnvOutput(const FilePath &sdkRoot)
             emSdkEnv.setCommand(CommandLine(scriptFile));
         } else {
             // File needs to be source'd, not executed.
-            emSdkEnv.setCommand({FilePath::fromString("bash").onDevice(sdkRoot),
+            emSdkEnv.setCommand({sdkRoot.withNewPath("bash"), {"-c", ". " + scriptFile}});
-                                 {"-c", ". " + scriptFile}});
         }
         emSdkEnv.runBlocking();
         const QString output = emSdkEnv.allOutput();
@@ -108,8 +107,7 @@ QVersionNumber WebAssemblyEmSdk::version(const FilePath &sdkRoot)
         Environment env;
         WebAssemblyEmSdk::addToEnvironment(sdkRoot, env);
         QLatin1String scriptFile{sdkRoot.osType() == OsType::OsTypeWindows ? "emcc.bat" : "emcc"};
-        FilePath script =
+        FilePath script = sdkRoot.withNewPath(scriptFile).searchOnDevice(env.path());
-                FilePath::fromString(scriptFile).onDevice(sdkRoot).searchOnDevice(env.path());
         const CommandLine command(script, {"-dumpversion"});
         QtcProcess emcc;
         emcc.setCommand(command);

src/plugins/webassembly/webassemblytoolchain.cpp

@@ -162,7 +162,6 @@ QList<ToolChain *> WebAssemblyToolChainFactory::autoDetect(
         const IDevice::Ptr &device)
 {
     Q_UNUSED(alreadyKnown)
-    Q_UNUSED(device)
 
     const FilePath sdk = WebAssemblyEmSdk::registeredEmSdk();
     if (!WebAssemblyEmSdk::isValid(sdk))
@@ -187,8 +186,7 @@ QList<ToolChain *> WebAssemblyToolChainFactory::autoDetect(
         const bool cLanguage = languageId == ProjectExplorer::Constants::C_LANGUAGE_ID;
         const QString script = QLatin1String(cLanguage ? "emcc" : "em++")
                 + QLatin1String(sdk.osType() == OsTypeWindows ? ".bat" : "");
-        const FilePath scriptFile =
+        const FilePath scriptFile = sdk.withNewPath(script).searchOnDevice(env.path());
-                FilePath::fromString(script).onDevice(sdk).searchOnDevice(env.path());
         toolChain->setCompilerCommand(scriptFile);
 
         const QString displayName = WebAssemblyToolChain::tr("Emscripten Compiler %1 for %2")