shader: Bug fix: Wrong local variable index in a block

internal/shader/expr.go

@@ -240,7 +240,7 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr) ([]shaderir.Expr,
 
 		var outParams []int
 		for _, p := range f.ir.OutParams {
-			idx := len(block.vars)
+			idx := block.totalLocalVariableNum()
 			block.vars = append(block.vars, variable{
 				typ: p,
 			})
@@ -257,7 +257,7 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr) ([]shaderir.Expr,
 				return nil, nil, nil, false
 			}
 
-			idx := len(block.vars)
+			idx := block.totalLocalVariableNum()
 			block.vars = append(block.vars, variable{
 				typ: t,
 			})
@@ -453,7 +453,7 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr) ([]shaderir.Expr,
 			return nil, nil, nil, false
 		}
 
-		idx := len(block.vars)
+		idx := block.totalLocalVariableNum()
 		block.vars = append(block.vars, variable{
 			typ: t,
 		})

internal/shader/shader.go

@@ -95,6 +95,14 @@ type block struct {
 	ir *shaderir.Block
 }
 
+func (b *block) totalLocalVariableNum() int {
+	c := len(b.vars)
+	if b.outer != nil {
+		c += b.outer.totalLocalVariableNum()
+	}
+	return c
+}
+
 func (b *block) findLocalVariable(name string) (int, shaderir.Type, bool) {
 	idx := 0
 	for outer := b.outer; outer != nil; outer = outer.outer {

internal/shader/testdata/for4.expected.vs

@@ -0,0 +1,21 @@
+void F0(in int l0, out int l1);
+void F1(out int l0);
+
+void F0(in int l0, out int l1) {
+	l1 = l0;
+	return;
+}
+
+void F1(out int l0) {
+	int l1 = 0;
+	l1 = 0;
+	for (int l2 = 0; l2 < 10; l2++) {
+		int l3 = 0;
+		int l4 = 0;
+		F0(l2, l3);
+		l4 = l3;
+		l1 = (l1) + (l4);
+	}
+	l0 = l1;
+	return;
+}

internal/shader/testdata/for4.go

@@ -0,0 +1,14 @@
+package main
+
+func Ident(x int) int {
+	return x
+}
+
+func Foo() int {
+	sum := 0
+	for i := 0; i < 10; i++ {
+		x := Ident(i)
+		sum += x
+	}
+	return sum
+}