shader: Bug fix: index out of range at defining a var

internal/shader/shader.go

@@ -110,6 +110,21 @@ func (b *block) findLocalVariable(name string) (int, shaderir.Type, bool) {
 	return 0, shaderir.Type{}, false
 }
 
+func (b *block) findLocalVariableByIndex(idx int) (shaderir.Type, bool) {
+	bs := []*block{b}
+	for outer := b.outer; outer != nil; outer = outer.outer {
+		bs = append(bs, outer)
+	}
+	for i := len(bs) - 1; i >= 0; i-- {
+		if len(bs[i].vars) <= idx {
+			idx -= len(bs[i].vars)
+			continue
+		}
+		return bs[i].vars[idx].typ, true
+	}
+	return shaderir.Type{}, false
+}
+
 type ParseError struct {
 	errs []string
 }

internal/shader/stmt.go

@@ -268,7 +268,12 @@ func (cs *compileState) assign(block *block, pos token.Pos, lhs, rhs []ast.Expr,
 			stmts = append(stmts, ss...)
 
 			if r[0].Type == shaderir.NumberExpr {
-				switch block.vars[l[0].Index].typ.Main {
+				t, ok := block.findLocalVariableByIndex(l[0].Index)
+				if !ok {
+					cs.addError(pos, fmt.Sprintf("unexpected local variable index: %d", l[0].Index))
+					return nil, false
+				}
+				switch t.Main {
 				case shaderir.Int:
 					r[0].ConstType = shaderir.ConstTypeInt
 				case shaderir.Float:

internal/shader/testdata/blocks2.expected.vs

@@ -0,0 +1,12 @@
+void F0(out vec2 l0) {
+	bool l1 = false;
+	l1 = true;
+	{
+		int l2 = 0;
+		l2 = 0;
+		l0 = vec2(l2);
+		return;
+	}
+	l0 = vec2(1.0);
+	return;
+}

internal/shader/testdata/blocks2.go

@@ -0,0 +1,10 @@
+package main
+
+func Foo() vec2 {
+	x := true
+	{
+		x := 0
+		return vec2(x)
+	}
+	return vec2(1)
+}