Remove union from SkFontStyle.

This is prompted by a bug in vc++ reported at
https://developercommunity.visualstudio.com/content/problem/86829/constexpr-initializing-struct-in-union-only-zero-i.html

Visual C++ will not properly constexpr initialize a struct inside a
union. Removing this construct also allows us to avoid writing and
reading from different members of a union.

Change-Id: I76e069ecce77ef21b7ad3821bf9c29e1b0843618
Reviewed-on: https://skia-review.googlesource.com/28300
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>

1 files changed, 11 insertions, 18 deletions

diff --git a/include/core/SkFontStyle.h b/include/core/SkFontStyle.h
index 306895d78f..a5e3034e1d 100644
--- a/include/core/SkFontStyle.h
+++ b/include/core/SkFontStyle.h
@@ -44,23 +44,23 @@ public:
         kOblique_Slant,
     };
 
-    SkFontStyle();
+    constexpr SkFontStyle(int weight, int width, Slant slant) : fValue(
+        (SkTPin<int>(weight, kInvisible_Weight, kExtraBlack_Weight)) +
+        (SkTPin<int>(width, kUltraCondensed_Width, kUltraExpanded_Width) << 16) +
+        (SkTPin<int>(slant, kUpright_Slant, kOblique_Slant) << 24)
+     ) { }
 
-    constexpr SkFontStyle(int weight, int width, Slant slant) : fUnion {{
-        static_cast<uint16_t>(SkTPin<int>(weight, kInvisible_Weight, kExtraBlack_Weight)),
-        static_cast<uint8_t >(SkTPin<int>(width, kUltraCondensed_Width, kUltraExpanded_Width)),
-        static_cast<uint8_t >(SkTPin<int>(slant, kUpright_Slant, kOblique_Slant))
-    }} { }
+    constexpr SkFontStyle() : SkFontStyle{kNormal_Weight, kNormal_Width, kUpright_Slant} { }
 
     static SkFontStyle FromOldStyle(unsigned oldStyle);
 
     bool operator==(const SkFontStyle& rhs) const {
-        return fUnion.fU32 == rhs.fUnion.fU32;
+        return fValue == rhs.fValue;
     }
 
-    int weight() const { return fUnion.fR.fWeight; }
-    int width() const { return fUnion.fR.fWidth; }
-    Slant slant() const { return (Slant)fUnion.fR.fSlant; }
+    int weight() const { return fValue & 0xFFFF; }
+    int width() const { return (fValue >> 16) & 0xFF; }
+    Slant slant() const { return (Slant)((fValue >> 24) & 0xFF); }
 
     static constexpr SkFontStyle Normal() {
         return SkFontStyle(kNormal_Weight, kNormal_Width, kUpright_Slant);
@@ -76,14 +76,7 @@ public:
     }
 
 private:
-    union {
-        struct {
-            uint16_t fWeight;   // 100 .. 900
-            uint8_t  fWidth;    // 1 .. 9
-            uint8_t  fSlant;    // 0 .. 2
-        } fR;
-        uint32_t    fU32;
-    } fUnion;
+    uint32_t fValue;
 };
 
 #endif