Do not call isFileCaseCorrect that often

'qbs resolve qtcreator.qbs' results:
macOs: 0m31.510s -> 0m26.417s

Change-Id: Ibd69ba87f5515e99776e6af2f87587e711213b41
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

2 files changed, 16 insertions, 5 deletions

diff --git a/src/lib/corelib/language/moduleloader.cpp b/src/lib/corelib/language/moduleloader.cpp
index 4f00a634c..9f3a3a53e 100644
--- a/src/lib/corelib/language/moduleloader.cpp
+++ b/src/lib/corelib/language/moduleloader.cpp
@@ -3760,12 +3760,23 @@ QString ModuleLoader::findExistingModulePath(const QString &searchPath,
         const QualifiedId &moduleName)
 {
     QString dirPath = searchPath + QStringLiteral("/modules");
+
+    // isFileCaseCorrect is a very expensive call on macOS, so we cache the value for the
+    // modules and search paths we've already processed
+    auto &moduleInfo = m_existingModulePathCache[{searchPath, moduleName}];
+    if (moduleInfo.first) // poor man's std::optional<QString>
+        return moduleInfo.second;
+
     for (const QString &moduleNamePart : moduleName) {
         dirPath = FileInfo::resolvePath(dirPath, moduleNamePart);
-        if (!FileInfo::exists(dirPath) || !FileInfo::isFileCaseCorrect(dirPath))
-            return {};
+        if (!FileInfo::exists(dirPath) || !FileInfo::isFileCaseCorrect(dirPath)) {
+            moduleInfo.first = true;
+            return moduleInfo.second = QString();
+        }
     }
-    return dirPath;
+
+    moduleInfo.first = true;
+    return moduleInfo.second = dirPath;
 }
 
 QVariantMap ModuleLoader::moduleProviderConfig(ModuleLoader::ProductContext &product)
diff --git a/src/lib/corelib/language/moduleloader.h b/src/lib/corelib/language/moduleloader.h
index 204c93ed4..410b2dde2 100644
--- a/src/lib/corelib/language/moduleloader.h
+++ b/src/lib/corelib/language/moduleloader.h
@@ -338,8 +338,7 @@ private:
     QStringList readExtraSearchPaths(Item *item, bool *wasSet = nullptr);
     void copyProperties(const Item *sourceProject, Item *targetProject);
     Item *wrapInProjectIfNecessary(Item *item);
-    static QString findExistingModulePath(const QString &searchPath,
-            const QualifiedId &moduleName);
+    QString findExistingModulePath(const QString &searchPath, const QualifiedId &moduleName);
 
     enum class ModuleProviderLookup { Regular, Fallback };
     struct ModuleProviderResult
@@ -412,6 +411,7 @@ private:
     ItemReader *m_reader;
     Evaluator *m_evaluator;
     QMap<QString, QStringList> m_moduleDirListCache;
+    QHash<std::pair<QString, QualifiedId>, std::pair<bool, QString>> m_existingModulePathCache;
 
     // The keys are file paths, the values are module prototype items accompanied by a profile.
     std::unordered_map<QString, std::vector<std::pair<Item *, QString>>> m_modulePrototypes;