Fix some gcc warnings and style suggestions

Building against gcc-10 produced warnings and style suggestions.
Fixed all the warnings, but only select style suggestions due to
readability and others appeared to be compiler confusion.

Tested: Compiled
    No functional impacts appear to have been made with these changes

Change-Id: I1adcce355b831ae8b178bfba9b89cc18fe4f3cf7
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/functor.hpp b/control/functor.hpp
index f631311..658c76a 100644
--- a/control/functor.hpp
+++ b/control/functor.hpp
@@ -87,7 +87,8 @@
     Properties& operator=(const Properties&) = default;
     Properties(Properties&&) = default;
     Properties& operator=(Properties&&) = default;
-    explicit Properties(U&& handler) : _handler(std::forward<U>(handler))
+    explicit Properties(U&& handler) :
+        _path(""), _intf(""), _prop(""), _handler(std::forward<U>(handler))
     {}
     Properties(const char* path, const char* intf, const char* prop,
                U&& handler) :
@@ -404,10 +405,11 @@
     void operator()(sdbusplus::bus::bus& bus, sdbusplus::message::message& msg,
                     Zone& zone) const
     {
-        std::string name;
-        bool hasOwner = false;
         if (msg)
         {
+            std::string name;
+            bool hasOwner = false;
+
             // Handle NameOwnerChanged signals
             msg.read(name);
 
diff --git a/control/zone.cpp b/control/zone.cpp
index 3c87654..9efb0c7 100644
--- a/control/zone.cpp
+++ b/control/zone.cpp
@@ -63,9 +63,9 @@
 {
     auto& fanDefs = std::get<fanListPos>(def);
 
-    for (auto& def : fanDefs)
+    for (auto& fanDef : fanDefs)
     {
-        _fans.emplace_back(std::make_unique<Fan>(bus, def));
+        _fans.emplace_back(std::make_unique<Fan>(bus, fanDef));
     }
 
     // Do not enable set speed events when in init mode
@@ -89,9 +89,9 @@
             _targetSpeed = _fans.front()->getTargetSpeed();
         }
         // Setup signal trigger for set speed events
-        for (auto& event : std::get<setSpeedEventsPos>(def))
+        for (auto& ssEvent : std::get<setSpeedEventsPos>(def))
         {
-            initEvent(event);
+            initEvent(ssEvent);
         }
         // Start timer for fan speed decreases
         _decTimer.restart(_decInterval);
@@ -523,7 +523,7 @@
     if (it != _persisted.end())
     {
         return std::any_of(it->second.begin(), it->second.end(),
-                           [&prop](auto& p) { return prop == p; });
+                           [&prop](const auto& p) { return prop == p; });
     }
 
     return persisted;
diff --git a/cooling-type/cooling_type.cpp b/cooling-type/cooling_type.cpp
index d996230..86b1385 100644
--- a/cooling-type/cooling_type.cpp
+++ b/cooling-type/cooling_type.cpp
@@ -102,9 +102,9 @@
     ObjectMap invObj = getObjectMap(objpath);
 
     // Update inventory
-    auto invMgrResponseMsg = util::SDBusPlus::lookupAndCallMethod(
+    static_cast<void>(util::SDBusPlus::lookupAndCallMethod(
         bus, util::INVENTORY_PATH, util::INVENTORY_INTF, "Notify",
-        std::move(invObj));
+        std::move(invObj)));
 }
 
 } // namespace type
diff --git a/cooling-type/cooling_type.hpp b/cooling-type/cooling_type.hpp
index 2622f6c..752c32c 100644
--- a/cooling-type/cooling_type.hpp
+++ b/cooling-type/cooling_type.hpp
@@ -44,7 +44,7 @@
      *
      * @param[in] bus - Dbus bus object
      */
-    CoolingType(sdbusplus::bus::bus& bus) : bus(bus)
+    explicit CoolingType(sdbusplus::bus::bus& bus) : bus(bus), gpioFd(-1)
     {
         // TODO: Issue openbmc/openbmc#1531 - means to default properties.
     }
@@ -75,7 +75,7 @@
     /** @brief Connection for sdbusplus bus */
     sdbusplus::bus::bus& bus;
     // File descriptor for the GPIO file we are going to read.
-    phosphor::fan::util::FileDescriptor gpioFd = -1;
+    phosphor::fan::util::FileDescriptor gpioFd;
     bool airCooled = false;
     bool waterCooled = false;
 
diff --git a/presence/tach.cpp b/presence/tach.cpp
index ee35878..3372d8e 100644
--- a/presence/tach.cpp
+++ b/presence/tach.cpp
@@ -119,12 +119,11 @@
 void Tach::propertiesChanged(size_t sensor,
                              const util::Properties<int64_t>& props)
 {
-    auto& s = state[sensor];
-
     // Find the Value property containing the speed.
     auto it = props.find(tachProperty);
     if (it != props.end())
     {
+        auto& s = state[sensor];
         std::get<int64_t>(s) = std::get<int64_t>(it->second);
 
         auto newState =
diff --git a/sdbusplus.hpp b/sdbusplus.hpp
index 9c3d08d..703895e 100644
--- a/sdbusplus.hpp
+++ b/sdbusplus.hpp
@@ -32,7 +32,7 @@
 class DBusError : public std::runtime_error
 {
   public:
-    DBusError(const char* msg) : std::runtime_error(msg)
+    explicit DBusError(const char* msg) : std::runtime_error(msg)
     {}
 };
 
diff --git a/utility.hpp b/utility.hpp
index 7db9047..4e8c226 100644
--- a/utility.hpp
+++ b/utility.hpp
@@ -40,7 +40,7 @@
     FileDescriptor& operator=(const FileDescriptor&) = delete;
     FileDescriptor& operator=(FileDescriptor&&) = default;
 
-    FileDescriptor(int fd) : fd(fd)
+    explicit FileDescriptor(int fd) : fd(fd)
     {}
 
     ~FileDescriptor()