CMake: Do not crash without a supported CMake

Do not crash when a CMake < 3.7 (no server-mode and no file-api) is
used.

Change-Id: I72a4ce6bb81d4fcf3d59508c72e46f422a8a00c0
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

4 files changed, 30 insertions, 23 deletions

diff --git a/src/plugins/cmakeprojectmanager/builddirmanager.cpp b/src/plugins/cmakeprojectmanager/builddirmanager.cpp
index 44aec2346e..2e99326d94 100644
--- a/src/plugins/cmakeprojectmanager/builddirmanager.cpp
+++ b/src/plugins/cmakeprojectmanager/builddirmanager.cpp
@@ -143,6 +143,13 @@ void BuildDirManager::updateReaderType(const BuildDirParameters &p,
         }
         m_reader = BuildDirReader::createReader(p);
 
+        if (!m_reader) {
+            TaskHub::addTask(BuildSystemTask(
+                Task::Error,
+                tr("The kit does not define a valid CMake tool to parse this project with.")));
+            return;
+        }
+
         connect(m_reader.get(),
                 &BuildDirReader::configurationStarted,
                 this,
diff --git a/src/plugins/cmakeprojectmanager/builddirreader.cpp b/src/plugins/cmakeprojectmanager/builddirreader.cpp
index 031f1ec6c7..091e6d1a6f 100644
--- a/src/plugins/cmakeprojectmanager/builddirreader.cpp
+++ b/src/plugins/cmakeprojectmanager/builddirreader.cpp
@@ -44,13 +44,14 @@ std::unique_ptr<BuildDirReader> BuildDirReader::createReader(const BuildDirParam
     CMakeTool *cmake = p.cmakeTool();
     QTC_ASSERT(p.isValid() && cmake, return {});
 
-    switch (cmake->readerType()) {
+    auto type = cmake->readerType();
+    if (!type)
+        return {};
+    switch (type.value()) {
     case CMakeTool::FileApi:
         return std::make_unique<FileApiReader>();
     case CMakeTool::ServerMode:
         return std::make_unique<ServerModeReader>();
-    default:
-        return {};
     }
 }
 
diff --git a/src/plugins/cmakeprojectmanager/cmaketool.cpp b/src/plugins/cmakeprojectmanager/cmaketool.cpp
index 8c77d3bccd..f487734b3d 100644
--- a/src/plugins/cmakeprojectmanager/cmaketool.cpp
+++ b/src/plugins/cmakeprojectmanager/cmaketool.cpp
@@ -69,10 +69,11 @@ static bool ignoreFileApi()
 
 static Utils::optional<CMakeTool::ReaderType> readerTypeFromString(const QString &input)
 {
+    // Do not try to be clever here, just use whatever is in the string!
     if (input == READER_TYPE_SERVERMODE)
         return CMakeTool::ServerMode;
     if (input == READER_TYPE_FILEAPI)
-        return ignoreFileApi() ? CMakeTool::ServerMode : CMakeTool::FileApi;
+        return CMakeTool::FileApi;
     return {};
 }
 
@@ -84,7 +85,6 @@ static QString readerTypeToString(const CMakeTool::ReaderType &type)
     case CMakeTool::FileApi:
         return QString(READER_TYPE_FILEAPI);
     }
-    return QString("<INVALID>");
 }
 
 // --------------------------------------------------------------------
@@ -120,9 +120,10 @@ public:
 ///////////////////////////
 // CMakeTool
 ///////////////////////////
-CMakeTool::CMakeTool(Detection d, const Core::Id &id) :
-    m_id(id), m_isAutoDetected(d == AutoDetection),
-    m_introspection(std::make_unique<Internal::IntrospectionData>())
+CMakeTool::CMakeTool(Detection d, const Core::Id &id)
+    : m_id(id)
+    , m_isAutoDetected(d == AutoDetection)
+    , m_introspection(std::make_unique<Internal::IntrospectionData>())
 {
     QTC_ASSERT(m_id.isValid(), m_id = Core::Id::fromString(QUuid::createUuid().toString()));
 }
@@ -198,7 +199,7 @@ bool CMakeTool::isValid() const
     if (!m_introspection->m_didAttemptToRun)
         supportedGenerators();
 
-    return m_introspection->m_didRun && (hasFileApi() || hasServerMode());
+    return m_introspection->m_didRun && readerType().has_value();
 }
 
 Utils::SynchronousProcessResponse CMakeTool::run(const QStringList &args, int timeoutS) const
@@ -223,7 +224,7 @@ QVariantMap CMakeTool::toMap() const
     data.insert(CMAKE_INFORMATION_QCH_FILE_PATH, m_qchFilePath.toString());
     data.insert(CMAKE_INFORMATION_AUTORUN, m_isAutoRun);
     data.insert(CMAKE_INFORMATION_AUTO_CREATE_BUILD_DIRECTORY, m_autoCreateBuildDirectory);
-    if (m_readerType.has_value())
+    if (m_readerType)
         data.insert(CMAKE_INFORMATION_READERTYPE,
                     Internal::readerTypeToString(m_readerType.value()));
     data.insert(CMAKE_INFORMATION_AUTODETECTED, m_isAutoDetected);
@@ -368,19 +369,17 @@ CMakeTool::PathMapper CMakeTool::pathMapper() const
     return [](const Utils::FilePath &fn) { return fn; };
 }
 
-CMakeTool::ReaderType CMakeTool::readerType() const
+Utils::optional<CMakeTool::ReaderType> CMakeTool::readerType() const
 {
-    if (!m_readerType.has_value()) {
-        // Find best possible reader type:
-        if (hasFileApi()) {
-            if (hasServerMode() && Internal::ignoreFileApi())
-                return ServerMode; // We were asked to fall back to server mode
-            return FileApi;
-        }
-        if (hasServerMode())
-            return ServerMode;
-    }
-    return m_readerType.value();
+    if (m_readerType)
+        return m_readerType; // Allow overriding the auto-detected value via .user files
+
+    // Find best possible reader type:
+    if (hasFileApi() && !Internal::ignoreFileApi())
+        return FileApi;
+    if (hasServerMode())
+        return ServerMode;
+    return {};
 }
 
 Utils::FilePath CMakeTool::searchQchFile(const Utils::FilePath &executable)
diff --git a/src/plugins/cmakeprojectmanager/cmaketool.h b/src/plugins/cmakeprojectmanager/cmaketool.h
index 40a79071cf..1d7bcde82e 100644
--- a/src/plugins/cmakeprojectmanager/cmaketool.h
+++ b/src/plugins/cmakeprojectmanager/cmaketool.h
@@ -110,7 +110,7 @@ public:
     void setPathMapper(const PathMapper &includePathMapper);
     PathMapper pathMapper() const;
 
-    ReaderType readerType() const;
+    Utils::optional<ReaderType> readerType() const;
 
     static Utils::FilePath searchQchFile(const Utils::FilePath &executable);