Fix: Over-optimistic moving of variable declaration to first usage (when usage is on the rhs of a '+=').

Author: DeanEdisGG

ShaderShrinker/Shrinker.Parser/Optimizations/JoinVariableDeclarationsWithAssignmentsExtension.cs

@@ -146,9 +146,14 @@ public static void JoinVariableDeclarationsWithAssignments(this SyntaxNode rootN
 
                                       // Or separated only by declarations all assigned in the single next statement?
                                       // (Only possible if the next statement is a multi-param function with out params.)
-                                      if (nearestUseNode is FunctionCallSyntaxNode &&
-                                          declWithNoDefs.NextSiblings.TakeWhile(o => o != nearestUseNode).All(o => o is VariableDeclarationSyntaxNode))
-                                          break;
+                                      if (nearestUseNode is FunctionCallSyntaxNode)
+                                      {
+                                          var nodes = declWithNoDefs.NextSiblings.TakeWhile(o => o != nearestUseNode).ToList();
+                                          if (nodes.All(o => o is VariableDeclarationSyntaxNode))
+                                              break;
+                                          if (nodes.Any(o => o.Token is SymbolOperatorToken))
+                                              break;
+                                      }
 
                                       // Move declaration to before definition.
                                       declWithNoDefs.Remove();
@@ -158,7 +163,7 @@ public static void JoinVariableDeclarationsWithAssignments(this SyntaxNode rootN
                                   return true;
                               });
 
-            // Declare variables when first assigned, if it would reduce code size.
+            // Declare variables when first assigned if it would reduce code size.
             // (I.e. If Variable name is longer than the type name)
             foreach (var functionNode in rootNode.FunctionDefinitions())
             {

ShaderShrinker/UnitTests/ShrinkerTests.cs

@@ -344,6 +344,21 @@ public void CheckJoiningDeclarationsAndDefinitionsWhenUsingVectorAccess()
             Assert.That(rootNode.ToCode().ToSimple(), Is.EqualTo(Code));
         }
 
+        [Test]
+        public void CheckDeclarationIsNotJoinedWithDefinitionFromFunctionCallOutParam()
+        {
+            var lexer = new Lexer();
+            lexer.Load("void a(out vec3 v) { v = vec3(1); } void f() { int a; vec3 b = vec3(0); b += g(a); }");
+
+            var options = CustomOptions.None();
+            options.JoinVariableDeclarationsWithAssignments = true;
+            var rootNode = new Parser(lexer)
+                .Parse()
+                .Simplify(options);
+
+            Assert.That(rootNode.ToCode().ToSimple(), Is.EqualTo("void a(out vec3 v) { v = vec3(1); } void f() { int a; vec3 b = vec3(0); b += g(a); }"));
+        }
+
         [Test]
         public void CheckDeclarationIsNotMovedIfAssignedInBracedCodeBranch()
         {
@@ -417,8 +432,8 @@ public void CheckDeclarationIsNotJoinedWithDefinitionIfDeepWithinIfPragma()
                 .Simplify(options);
 
             Assert.That(rootNode.ToCode().ToSimple(), Is.EqualTo("void f() { #ifdef AA { vec2 v = vec2(1); #else vec2 v = vec2(2); #endif #ifdef AA } #endif }"));
-        }
-
+        }      
+        
         [Test, Sequential]
         public void CheckSimplifyingFloats(
             [Values("10.0", "1.1", "0.10", "0.0000", "-0.09", "100.0", "100.1", "1100000.", "1.23f", "-0.1f", ".0f", "0.f", "10.00F", "102.", "001.1", "3.141592653589793238462643383279502884197", "-3.141592653589793238462643383279502884197", "1.541182543454656e-4", "1e10", "0011.0", "-0011.0", "00.0", "0.00001", "0.00062")] string code,