diff --git a/src/citra_qt/main.h b/src/citra_qt/main.h
index c95ca9f86..bca836ca8 100644
--- a/src/citra_qt/main.h
+++ b/src/citra_qt/main.h
@@ -83,14 +83,6 @@ class GMainWindow : public QMainWindow {
     /// Max number of recently loaded items to keep track of
     static const int max_recent_files_item = 10;
 
-    // TODO: Make use of this!
-    enum {
-        UI_IDLE,
-        UI_EMU_BOOTING,
-        UI_EMU_RUNNING,
-        UI_EMU_STOPPING,
-    };
-
 public:
     void filterBarSetChecked(bool state);
     void UpdateUITheme();
diff --git a/src/common/bit_set.h b/src/common/bit_set.h
index 0598b60df..1e6b238bc 100644
--- a/src/common/bit_set.h
+++ b/src/common/bit_set.h
@@ -92,8 +92,6 @@ static inline int LeastSignificantSetBit(u64 val) {
 //   operation.)
 // - Counting set bits using .Count() - see comment on that method.
 
-// TODO: use constexpr when MSVC gets out of the Dark Ages
-
 template <typename IntTy>
 class BitSet {
     static_assert(!std::is_signed_v<IntTy>, "BitSet should not be used with signed types");
@@ -102,12 +100,12 @@ public:
     // A reference to a particular bit, returned from operator[].
     class Ref {
     public:
-        Ref(Ref&& other) : m_bs(other.m_bs), m_mask(other.m_mask) {}
-        Ref(BitSet* bs, IntTy mask) : m_bs(bs), m_mask(mask) {}
-        operator bool() const {
+        constexpr Ref(Ref&& other) : m_bs(other.m_bs), m_mask(other.m_mask) {}
+        constexpr Ref(BitSet* bs, IntTy mask) : m_bs(bs), m_mask(mask) {}
+        constexpr operator bool() const {
             return (m_bs->m_val & m_mask) != 0;
         }
-        bool operator=(bool set) {
+        constexpr bool operator=(bool set) {
             m_bs->m_val = (m_bs->m_val & ~m_mask) | (set ? m_mask : 0);
             return set;
         }
@@ -120,26 +118,26 @@ public:
     // A STL-like iterator is required to be able to use range-based for loops.
     class Iterator {
     public:
-        Iterator(const Iterator& other) : m_val(other.m_val) {}
-        Iterator(IntTy val) : m_val(val) {}
-        int operator*() {
+        constexpr Iterator(const Iterator& other) : m_val(other.m_val) {}
+        constexpr Iterator(IntTy val) : m_val(val) {}
+        constexpr int operator*() {
             // This will never be called when m_val == 0, because that would be the end() iterator
             return LeastSignificantSetBit(m_val);
         }
-        Iterator& operator++() {
+        constexpr Iterator& operator++() {
             // Unset least significant set bit
             m_val &= m_val - IntTy(1);
             return *this;
         }
-        Iterator operator++(int _) {
+        constexpr Iterator operator++(int) {
             Iterator other(*this);
             ++*this;
             return other;
         }
-        bool operator==(Iterator other) const {
+        constexpr bool operator==(Iterator other) const {
             return m_val == other.m_val;
         }
-        bool operator!=(Iterator other) const {
+        constexpr bool operator!=(Iterator other) const {
             return m_val != other.m_val;
         }
 
@@ -147,59 +145,59 @@ public:
         IntTy m_val;
     };
 
-    BitSet() : m_val(0) {}
-    explicit BitSet(IntTy val) : m_val(val) {}
-    BitSet(std::initializer_list<int> init) {
+    constexpr BitSet() : m_val(0) {}
+    constexpr explicit BitSet(IntTy val) : m_val(val) {}
+    constexpr BitSet(std::initializer_list<int> init) {
         m_val = 0;
         for (int bit : init)
             m_val |= (IntTy)1 << bit;
     }
 
-    static BitSet AllTrue(std::size_t count) {
+    constexpr static BitSet AllTrue(std::size_t count) {
         return BitSet(count == sizeof(IntTy) * 8 ? ~(IntTy)0 : (((IntTy)1 << count) - 1));
     }
 
-    Ref operator[](std::size_t bit) {
+    constexpr Ref operator[](std::size_t bit) {
         return Ref(this, (IntTy)1 << bit);
     }
-    const Ref operator[](std::size_t bit) const {
+    constexpr const Ref operator[](std::size_t bit) const {
         return (*const_cast<BitSet*>(this))[bit];
     }
-    bool operator==(BitSet other) const {
+    constexpr bool operator==(BitSet other) const {
         return m_val == other.m_val;
     }
-    bool operator!=(BitSet other) const {
+    constexpr bool operator!=(BitSet other) const {
         return m_val != other.m_val;
     }
-    bool operator<(BitSet other) const {
+    constexpr bool operator<(BitSet other) const {
         return m_val < other.m_val;
     }
-    bool operator>(BitSet other) const {
+    constexpr bool operator>(BitSet other) const {
         return m_val > other.m_val;
     }
-    BitSet operator|(BitSet other) const {
+    constexpr BitSet operator|(BitSet other) const {
         return BitSet(m_val | other.m_val);
     }
-    BitSet operator&(BitSet other) const {
+    constexpr BitSet operator&(BitSet other) const {
         return BitSet(m_val & other.m_val);
     }
-    BitSet operator^(BitSet other) const {
+    constexpr BitSet operator^(BitSet other) const {
         return BitSet(m_val ^ other.m_val);
     }
-    BitSet operator~() const {
+    constexpr BitSet operator~() const {
         return BitSet(~m_val);
     }
-    BitSet& operator|=(BitSet other) {
+    constexpr BitSet& operator|=(BitSet other) {
         return *this = *this | other;
     }
-    BitSet& operator&=(BitSet other) {
+    constexpr BitSet& operator&=(BitSet other) {
         return *this = *this & other;
     }
-    BitSet& operator^=(BitSet other) {
+    constexpr BitSet& operator^=(BitSet other) {
         return *this = *this ^ other;
     }
     operator u32() = delete;
-    operator bool() {
+    constexpr operator bool() {
         return m_val != 0;
     }
 
@@ -207,14 +205,14 @@ public:
     // Dolphin's official builds do not currently assume POPCNT support on x86,
     // so slower explicit bit twiddling is generated.  Still should generally
     // be faster than a loop.
-    unsigned int Count() const {
+    constexpr u32 Count() const {
         return CountSetBits(m_val);
     }
 
-    Iterator begin() const {
+    constexpr Iterator begin() const {
         return Iterator(m_val);
     }
-    Iterator end() const {
+    constexpr Iterator end() const {
         return Iterator(0);
     }