ProjectExplorer: Allow gcc autodetection on docker devices

This uses a separate branch for the remote detection and leaves the
local development host path untouched.

Ideally the code should be identical, but currently the environment
handling on remote devices is not on par with the local cases, yet
good enough to find normal gcc installations.

Change-Id: I6762299d8ddfdf2aceb0d57cc77ab71fcc83788b
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/projectexplorer/gcctoolchain.cpp

@@ -1035,23 +1035,47 @@ QList<ToolChain *> GccToolChainFactory::detectForImport(const ToolChainDescripti
     return QList<ToolChain *>();
 }
 
-QList<ToolChain *> GccToolChainFactory::autoDetectToolchains(
+
+static FilePaths findCompilerCandidates(const IDevice::Ptr &device,
                                         const QString &compilerName,
-        DetectVariants detectVariants,
+                                        bool detectVariants)
-        const Id language,
-        const Id requiredTypeId,
-        const QList<ToolChain *> &alreadyKnown,
-        const IDevice::Ptr &device,
-        const ToolchainChecker &checker)
 {
-    Q_UNUSED(device)
+    const QFileInfo fi(compilerName);
+    if (device.isNull() && fi.isAbsolute() && fi.isFile())
+        return {FilePath::fromString(compilerName)};
+
+    QStringList nameFilters(compilerName);
+    if (detectVariants) {
+        nameFilters
+                << compilerName + "-[1-9]*" // "clang-8", "gcc-5"
+                << ("*-" + compilerName) // "avr-gcc", "avr32-gcc"
+                << ("*-" + compilerName + "-[1-9]*")// "avr-gcc-4.8.1", "avr32-gcc-4.4.7"
+                << ("*-*-*-" + compilerName) // "arm-none-eabi-gcc"
+                << ("*-*-*-" + compilerName + "-[1-9]*") // "arm-none-eabi-gcc-9.1.0"
+                << ("*-*-*-*-" + compilerName) // "x86_64-pc-linux-gnu-gcc"
+                << ("*-*-*-*-" + compilerName
+                    + "-[1-9]*"); // "x86_64-pc-linux-gnu-gcc-7.4.1"
+    }
 
     FilePaths compilerPaths;
-    QFileInfo fi(compilerName);
+
-    if (fi.isAbsolute()) {
+    if (!device.isNull()) {
-        if (fi.isFile())
+        // FIXME: Merge with block below
-            compilerPaths << FilePath::fromString(compilerName);
+        FilePaths searchPaths = device->systemEnvironment().path();
+        for (const FilePath &deviceDir : qAsConst(searchPaths)) {
+            static const QRegularExpression regexp(binaryRegexp);
+            const FilePath globalDir = device->mapToGlobalPath(deviceDir);
+            const FilePaths fileNames = device->directoryEntries(globalDir, nameFilters,
+                                                                 QDir::Files | QDir::Executable);
+            for (const FilePath &fileName : fileNames) {
+                if (fileName.fileName() == compilerName)
+                    compilerPaths << fileName;
+                else if (regexp.match(fileName.path()).hasMatch())
+                    compilerPaths << fileName;
+            }
+        }
     } else {
+        // The normal, local host case.
         FilePaths searchPaths = Environment::systemEnvironment().path();
         searchPaths << gnuSearchPathsFromRegistry();
         searchPaths << atmelSearchPathsFromRegistry();
@@ -1066,18 +1090,6 @@ QList<ToolChain *> GccToolChainFactory::autoDetectToolchains(
         for (const FilePath &dir : qAsConst(searchPaths)) {
             static const QRegularExpression regexp(binaryRegexp);
             QDir binDir(dir.toString());
-            QStringList nameFilters(compilerName);
-            if (detectVariants == DetectVariants::Yes) {
-                nameFilters
-                        << compilerName + "-[1-9]*" // "clang-8", "gcc-5"
-                        << ("*-" + compilerName) // "avr-gcc", "avr32-gcc"
-                        << ("*-" + compilerName + "-[1-9]*")// "avr-gcc-4.8.1", "avr32-gcc-4.4.7"
-                        << ("*-*-*-" + compilerName) // "arm-none-eabi-gcc"
-                        << ("*-*-*-" + compilerName + "-[1-9]*") // "arm-none-eabi-gcc-9.1.0"
-                        << ("*-*-*-*-" + compilerName) // "x86_64-pc-linux-gnu-gcc"
-                        << ("*-*-*-*-" + compilerName
-                            + "-[1-9]*"); // "x86_64-pc-linux-gnu-gcc-7.4.1"
-            }
             nameFilters = transform(nameFilters, [](const QString &baseName) {
                 return HostOsInfo::withExecutableSuffix(baseName);
             });
@@ -1093,6 +1105,21 @@ QList<ToolChain *> GccToolChainFactory::autoDetectToolchains(
         }
     }
 
+    return compilerPaths;
+}
+
+QList<ToolChain *> GccToolChainFactory::autoDetectToolchains(
+        const QString &compilerName,
+        DetectVariants detectVariants,
+        const Id language,
+        const Id requiredTypeId,
+        const QList<ToolChain *> &alreadyKnown,
+        const IDevice::Ptr &device,
+        const ToolchainChecker &checker)
+{
+    const FilePaths compilerPaths =
+        findCompilerCandidates(device, compilerName, detectVariants == DetectVariants::Yes);
+
     QList<ToolChain *> existingCandidates
             = filtered(alreadyKnown, [requiredTypeId, language, &checker](const ToolChain *tc) {
         if (tc->typeId() != requiredTypeId)