ProjectExplorer: Prevent build directory on non-existing drive

A drive that is not actually there is apparently different enough from a
"normal" non-writable location to seriously throw off some build tools,
so spend some effort in preventing this.

Fixes: QTCREATORBUG-25633
Change-Id: I5a15b0b2a3a882a08f50866c23e4d45c93fd78c9
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/aspects.cpp

@@ -1010,6 +1010,8 @@ void StringAspect::setValidationFunction(const FancyLineEdit::ValidationFunction
     d->m_validator = validator;
     if (d->m_lineEditDisplay)
         d->m_lineEditDisplay->setValidationFunction(d->m_validator);
+    else if (d->m_pathChooserDisplay)
+        d->m_pathChooserDisplay->setValidationFunction(d->m_validator);
 }
 
 void StringAspect::setOpenTerminalHandler(const std::function<void ()> &openTerminal)
@@ -1060,6 +1062,8 @@ void StringAspect::addToLayout(LayoutBuilder &builder)
         d->m_pathChooserDisplay->setExpectedKind(d->m_expectedKind);
         if (!d->m_historyCompleterKey.isEmpty())
             d->m_pathChooserDisplay->setHistoryCompleter(d->m_historyCompleterKey);
+        if (d->m_validator)
+            d->m_pathChooserDisplay->setValidationFunction(d->m_validator);
         d->m_pathChooserDisplay->setEnvironment(d->m_environment);
         d->m_pathChooserDisplay->setBaseDirectory(d->m_baseFileName);
         d->m_pathChooserDisplay->setOpenTerminalHandler(d->m_openTerminal);

src/plugins/projectexplorer/buildaspects.cpp

@@ -34,6 +34,7 @@
 #include <utils/fileutils.h>
 #include <utils/infolabel.h>
 #include <utils/layoutbuilder.h>
+#include <utils/pathchooser.h>
 
 #include <QLayout>
 
@@ -56,6 +57,12 @@ BuildDirectoryAspect::BuildDirectoryAspect(const BuildConfiguration *bc) : d(new
     setLabelText(tr("Build directory:"));
     setDisplayStyle(PathChooserDisplay);
     setExpectedKind(Utils::PathChooser::Directory);
+    setValidationFunction([this](FancyLineEdit *edit, QString *error) {
+        const FilePath fixedDir = fixupDir(FilePath::fromString(edit->text()));
+        if (!fixedDir.isEmpty())
+            edit->setText(fixedDir.toUserOutput());
+        return pathChooser() ? pathChooser()->defaultValidationFunction()(edit, error) : true;
+    });
     setOpenTerminalHandler([this, bc] {
         Core::FileUtils::openTerminal(value(), bc->environment());
     });
@@ -123,6 +130,28 @@ void BuildDirectoryAspect::addToLayout(LayoutBuilder &builder)
     }
 }
 
+FilePath BuildDirectoryAspect::fixupDir(const FilePath &dir)
+{
+    if (dir.needsDevice() || !HostOsInfo::isWindowsHost())
+        return {};
+    const QString dirString = dir.toString().toLower();
+    if (dirString.length() < 2)
+        return {};
+    if (!dirString.at(0).isLetter())
+        return {};
+    const QStringList drives = Utils::transform(QDir::drives(), [](const QFileInfo &fi) {
+        return fi.absoluteFilePath().toLower().chopped(1);
+    });
+    if (!Utils::contains(drives, [&dirString](const QString &drive) {
+            return dirString.startsWith(drive);
+        }) && !drives.isEmpty()) {
+        QString newDir = dirString;
+        newDir.replace(0, 2, drives.first());
+        return FilePath::fromString(newDir);
+    }
+    return {};
+}
+
 void BuildDirectoryAspect::updateProblemLabel()
 {
     if (!d->problemLabel)

src/plugins/projectexplorer/buildaspects.h

@@ -47,6 +47,8 @@ public:
 
     void addToLayout(Utils::LayoutBuilder &builder) override;
 
+    static Utils::FilePath fixupDir(const Utils::FilePath &dir);
+
 private:
     void toMap(QVariantMap &map) const override;
     void fromMap(const QVariantMap &map) override;

src/plugins/projectexplorer/buildconfiguration.cpp

@@ -257,6 +257,9 @@ void BuildConfiguration::setBuildDirectory(const FilePath &dir)
     if (dir == d->m_buildDirectoryAspect->filePath())
         return;
     d->m_buildDirectoryAspect->setFilePath(dir);
+    const FilePath fixedDir = BuildDirectoryAspect::fixupDir(buildDirectory());
+    if (!fixedDir.isEmpty())
+        d->m_buildDirectoryAspect->setFilePath(fixedDir);
     emitBuildDirectoryChanged();
 }