QmakeProjectManager: Try harder not to access nodes of in-parse project

For extra safety, do not touch the project nodes if any build system of
any build configuration is currently parsing.
This is a bit of a stab in the dark, as I cannot reproduce the crash
described in the linked bug report.

Task-number: QTCREATORBUG-23597
Change-Id: Ie62a94232e89d8fba5866ea3572535e2ab209924
Reviewed-by: hjk <hjk@qt.io>

src/plugins/projectexplorer/project.cpp

@@ -320,7 +320,7 @@ bool Project::removeTarget(Target *target)
     return true;
 }
 
-QList<Target *> Project::targets() const
+const QList<Target *> Project::targets() const
 {
     return Utils::toRawPointer<QList>(d->m_targets);
 }

src/plugins/projectexplorer/project.h

@@ -106,7 +106,7 @@ public:
     Target *addTargetForKit(Kit *kit);
     bool removeTarget(Target *target);
 
-    QList<Target *> targets() const;
+    const QList<Target *> targets() const;
     // Note: activeTarget can be 0 (if no targets are defined).
     Target *activeTarget() const;
     Target *target(Core::Id id) const;

src/plugins/qmakeprojectmanager/profileeditor.cpp

@@ -37,6 +37,7 @@
 #include <coreplugin/fileiconprovider.h>
 #include <extensionsystem/pluginmanager.h>
 #include <qtsupport/qtsupportconstants.h>
+#include <projectexplorer/buildconfiguration.h>
 #include <projectexplorer/projectexplorerconstants.h>
 #include <projectexplorer/target.h>
 #include <projectexplorer/session.h>
@@ -85,12 +86,24 @@ QString ProFileEditorWidget::checkForPrfFile(const QString &baseName) const
 {
     const FilePath projectFile = textDocument()->filePath();
     const QmakePriFileNode *projectNode = nullptr;
+
+    // FIXME: Remove this check once project nodes are fully "static".
     for (const Project * const project : SessionManager::projects()) {
-        if (Target *t = project->activeTarget()) {
+        static const auto isParsing = [](const Project *project) {
-            if (t->buildSystem()->isParsing())
+            for (const Target * const t : project->targets()) {
-                continue;
+                for (const BuildConfiguration * const bc : t->buildConfigurations()) {
+                    if (bc->buildSystem()->isParsing())
+                        return true;
                 }
-        projectNode = dynamic_cast<const QmakePriFileNode *>(project->rootProjectNode()
+            }
+            return false;
+        };
+        if (isParsing(project))
+            continue;
+
+        ProjectNode * const rootNode = project->rootProjectNode();
+        QTC_ASSERT(rootNode, continue);
+        projectNode = dynamic_cast<const QmakePriFileNode *>(rootNode
                 ->findProjectNode([&projectFile](const ProjectNode *pn) {
             return pn->filePath() == projectFile;
         }));