CMakePM: Allow using CMakeCache.txt as project file

The CMakeCache.txt file has CMAKE_HOME_DIRECTORY pointing to the
project source directory used to configure the project.

Use that as source directory, and the directory of CMakeCache.txt as the
build directory.

Task-number: QTCREATORBUG-24439
Task-number: QTCREATORBUG-30507
Change-Id: Ib032406b014f8f7ee5fc1d47bbe3796c6b8f8060
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/plugins/cmakeprojectmanager/CMakeProjectManager.json.in

@@ -38,6 +38,7 @@
         "    <sub-class-of type='text/x-cmake'/>",
         "    <comment>CMake Project file</comment>",
         "    <glob pattern='CMakeLists.txt'/>",
+        "    <glob pattern='CMakeCache.txt'/>",
         "  </mime-type>",
         "</mime-info>"
     ]

src/plugins/cmakeprojectmanager/builddirparameters.cpp

@@ -5,6 +5,7 @@
 
 #include "cmakebuildconfiguration.h"
 #include "cmakebuildsystem.h"
+#include "cmakeprojectconstants.h"
 #include "cmakekitaspect.h"
 #include "cmaketoolmanager.h"
 

src/plugins/cmakeprojectmanager/cmakeproject.cpp

@@ -29,11 +29,24 @@ using namespace CMakeProjectManager::Internal;
 
 namespace CMakeProjectManager {
 
+static FilePath cmakeListTxtFromFilePath(const FilePath &filepath)
+{
+    if (filepath.endsWith(Constants::CMAKE_CACHE_TXT)) {
+        QString errorMessage;
+        const CMakeConfig config = CMakeConfig::fromFile(filepath, &errorMessage);
+        const FilePath cmakeListsTxt = config.filePathValueOf("CMAKE_HOME_DIRECTORY")
+                                           .pathAppended(Constants::CMAKE_LISTS_TXT);
+        if (cmakeListsTxt.exists())
+            return cmakeListsTxt;
+    }
+    return filepath;
+}
+
 /*!
   \class CMakeProject
 */
 CMakeProject::CMakeProject(const FilePath &fileName)
-    : Project(Utils::Constants::CMAKE_MIMETYPE, fileName)
+    : Project(Utils::Constants::CMAKE_MIMETYPE, cmakeListTxtFromFilePath(fileName))
     , m_settings(this, true)
 {
     setId(CMakeProjectManager::Constants::CMAKE_PROJECT_ID);
@@ -47,6 +60,9 @@ CMakeProject::CMakeProject(const FilePath &fileName)
     setHasMakeInstallEquivalent(false);
 
     readPresets();
+
+    if (fileName.endsWith(Constants::CMAKE_CACHE_TXT))
+        m_buildDirToImport = fileName.parentDir();
 }
 
 CMakeProject::~CMakeProject()
@@ -332,6 +348,11 @@ void CMakeProject::readPresets()
     }
 }
 
+FilePath CMakeProject::buildDirectoryToImport() const
+{
+    return m_buildDirToImport;
+}
+
 bool CMakeProject::setupTarget(Target *t)
 {
     t->updateDefaultBuildConfigurations();

src/plugins/cmakeprojectmanager/cmakeproject.h

@@ -31,6 +31,7 @@ public:
 
     Internal::PresetsData presetsData() const;
     void readPresets();
+    Utils::FilePath buildDirectoryToImport() const;
 
     void setOldPresetKits(const QList<ProjectExplorer::Kit *> &presetKits) const;
     QList<ProjectExplorer::Kit *> oldPresetKits() const;
@@ -54,6 +55,7 @@ private:
     ProjectExplorer::Tasks m_issues;
     Internal::PresetsData m_presetsData;
     Internal::CMakeSpecificSettings m_settings;
+    Utils::FilePath m_buildDirToImport;
 };
 
 } // namespace CMakeProjectManager

src/plugins/cmakeprojectmanager/cmakeprojectimporter.cpp

@@ -167,6 +167,9 @@ static QString displayPresetName(const QString &presetName)
 
 FilePaths CMakeProjectImporter::importCandidates()
 {
+    if (!m_project->buildDirectoryToImport().isEmpty())
+        return {m_project->buildDirectoryToImport()};
+
     FilePaths candidates = presetCandidates();
 
     if (candidates.isEmpty()) {
@@ -299,6 +302,13 @@ static QVariant findOrRegisterDebugger(
 
 Target *CMakeProjectImporter::preferredTarget(const QList<Target *> &possibleTargets)
 {
+    if (!m_project->buildDirectoryToImport().isEmpty()) {
+        return Utils::findOrDefault(possibleTargets, [this](const Target *t) {
+            return t->activeBuildConfiguration()->buildDirectory()
+                   == m_project->buildDirectoryToImport();
+        });
+    }
+
     for (Kit *kit : m_project->oldPresetKits()) {
         const bool haveKit = Utils::contains(possibleTargets, [kit](const auto &target) {
             return target->kit() == kit;