ProjectExplorer: Replace the fromMap error return value

... by some out-of-band mechanism, keeping previous functionality.

The driving reason is to get the same fromMap signature as in the
AspectContainer base, however, the whole mechanism seems rather useless:
There are only a few places that actually ever could report errors,
in those places "moving on" looks ok, too, and these few places
are not conceptually different than a lot others.

Removal of this (new) mechanism is left for later.

Change-Id: Ibe7a0456bc3b84a84e942231f14446e783372d76
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/mesonprojectmanager/mesonbuildconfiguration.cpp

@@ -144,14 +144,13 @@ void MesonBuildConfiguration::toMap(QVariantMap &map) const
     map[Constants::BuildConfiguration::PARAMETERS_KEY] = m_parameters;
 }
 
-bool MesonBuildConfiguration::fromMap(const QVariantMap &map)
+void MesonBuildConfiguration::fromMap(const QVariantMap &map)
 {
-    auto res = ProjectExplorer::BuildConfiguration::fromMap(map);
+    ProjectExplorer::BuildConfiguration::fromMap(map);
     m_buildSystem = new MesonBuildSystem{this};
     m_buildType = mesonBuildType(
         map.value(Constants::BuildConfiguration::BUILD_TYPE_KEY).toString());
     m_parameters = map.value(Constants::BuildConfiguration::PARAMETERS_KEY).toString();
-    return res;
 }
 
 class MesonBuildSettingsWidget : public NamedWidget

src/plugins/mesonprojectmanager/mesonbuildconfiguration.h

@@ -31,7 +31,8 @@ signals:
 
 private:
     void toMap(QVariantMap &map) const override;
-    bool fromMap(const QVariantMap &map) override;
+    void fromMap(const QVariantMap &map) override;
+
     MesonBuildType m_buildType;
     ProjectExplorer::NamedWidget *createConfigWidget() final;
     MesonBuildSystem *m_buildSystem = nullptr;

src/plugins/mesonprojectmanager/ninjabuildstep.cpp

@@ -206,7 +206,7 @@ void NinjaBuildStep::toMap(QVariantMap &map) const
     map.insert(TOOL_ARGUMENTS_KEY, m_commandArgs);
 }
 
-bool NinjaBuildStep::fromMap(const QVariantMap &map)
+void NinjaBuildStep::fromMap(const QVariantMap &map)
 {
     m_targetName = map.value(TARGETS_KEY).toString();
     m_commandArgs = map.value(TOOL_ARGUMENTS_KEY).toString();

src/plugins/mesonprojectmanager/ninjabuildstep.h

@@ -27,7 +27,7 @@ public:
     Q_SIGNAL void commandChanged();
 
     void toMap(QVariantMap &map) const override;
-    bool fromMap(const QVariantMap &map) override;
+    void fromMap(const QVariantMap &map) override;
 
 private:
     void update(bool parsingSuccessful);