Fix bug 'not a swizzle' with custom struct (#284)

Fixes #282

src/rewriter.fs

@@ -19,11 +19,9 @@ let private swizzleIndex = function
     | 'a' | 'w' | 'q' -> 3
     | c -> failwithf "not a swizzle (%c) " c
 
-let private renameSwizzle field =
-    field |> String.map (fun c -> options.canonicalFieldNames.[swizzleIndex c])
-
 let renameField field =
-    if isFieldSwizzle field then renameSwizzle field
+    if isFieldSwizzle field then
+        field |> String.map (fun c -> options.canonicalFieldNames.[swizzleIndex c])
     else field
 
 // Remove useless spaces in macros
@@ -250,7 +248,7 @@ let private simplifyVec (constr: Ident) args =
 
     // vec3(a.x, b.xy) => vec3(a.x, b)
     let rec dropLastSwizzle = function
-        | [Dot (expr, field) as last] ->
+        | [Dot (expr, field) as last] when isFieldSwizzle field ->
             match [for c in field -> swizzleIndex c] with
             | [0] | [0; 1] | [0; 1; 2] | [0; 1; 2; 3] -> [expr]
             | _ -> [last]

tests/commands.txt

@@ -20,7 +20,7 @@
 --no-remove-unused --format indented --no-renaming -o tests/unit/forward_declaration.frag.expected tests/unit/forward_declaration.frag
 --no-remove-unused --format indented --no-renaming --move-declarations -o tests/unit/conditionals.frag.expected tests/unit/conditionals.frag
 --no-renaming --no-inlining --format indented -o tests/unit/pi.frag.expected tests/unit/pi.frag
---no-renaming --no-inlining --format indented -o tests/unit/vectors.frag.expected tests/unit/vectors.frag
+ --no-remove-unused --no-renaming --no-inlining --format indented -o tests/unit/vectors.frag.expected tests/unit/vectors.frag
 --no-renaming --format indented -o tests/unit/deadcode.frag.expected tests/unit/deadcode.frag
 --no-renaming --no-inlining --format indented -o tests/unit/augmented.frag.expected tests/unit/augmented.frag
 --no-remove-unused --no-renaming -o tests/unit/loop.frag.expected tests/unit/loop.frag

tests/unit/vectors.frag

@@ -26,4 +26,15 @@ float withExtraComponents() {
     return v2.x + v3.x + v4.x;
 }
 
-void main() { swizzles(); constructor(); constructors(); withExtraComponents(); }
+struct S{
+  vec2 p1;
+  vec2 cp1;
+  vec2 cp2;
+  vec2 p2;
+};
+
+vec2 calc(S points, float t) {
+  // #282 - not a swizzle
+  vec4 m1m2 = mix(vec4(points.p1, points.cp1), vec4(points.cp1, points.cp2), t);
+  return m1m2.xy;
+}

tests/unit/vectors.frag.expected

@@ -22,11 +22,9 @@ float withExtraComponents()
   vec3 v3=vec3(1,2,v2);
   vec4 v4=vec4(v2,v3);
   return v2.x+v3.x+v4.x;
-}
-void main()
+}struct S{vec2 p1;vec2 cp1;vec2 cp2;vec2 p2;};
+vec2 calc(S points,float t)
 {
-  swizzles();
-  constructor();
-  constructors();
-  withExtraComponents();
+  vec4 m1m2=mix(vec4(points.p1,points.cp1),vec4(points.cp1,points.cp2),t);
+  return m1m2.xy;
 }