attempt to fix an ASAN error. exercise smolscale usage in more test

src/smolscale-generic.c

@@ -1635,8 +1635,8 @@ scale_horizontal (const SmolScaleCtx *scale_ctx,
         row_in = (const char *) vertical_ctx->in_aligned;
     }
 
-    scale_ctx->unpack_row_func ((const uint32_t *) row_in,
-                                unpacked_in,
+    scale_ctx->unpack_row_func ((const void *) row_in,
+                                (void *)unpacked_in,
                                 scale_ctx->width_in);
     scale_ctx->hfilter_func (scale_ctx,
                              unpacked_in,
@@ -2316,7 +2316,7 @@ scale_outrow_copy (const SmolScaleCtx *scale_ctx,
                       inrow_ofs_to_pointer (scale_ctx, row_index),
                       vertical_ctx->parts_row [0]);
 
-    scale_ctx->pack_row_func (vertical_ctx->parts_row [0], row_out, scale_ctx->width_out);
+    scale_ctx->pack_row_func ((const void *)(vertical_ctx->parts_row [0]), (void *)row_out, scale_ctx->width_out);
 }
 
 /* --------------- *

tests/testthat/test-smolscale.R

@@ -0,0 +1,34 @@
+
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+# Exercise the library toensure there are no memory errors when 
+# used with R.
+# Any such errors will hopefully be picked up the test builds for:
+#   clang-asan, rchk, valgrind
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+test_that("smolscale works", {
+
+  nr <- nr_duplicate(deer_sprites[[1]])
+  for (w in c(10, 100, 400, 1000)) {
+    expect_no_error({
+      nr_resize(nr, w, w) 
+    })
+  }
+
+
+  orders <- c('RGBA', 'BGRA', 'ARGB', 'ABGR')
+
+
+  for (src_order in orders) {
+    for (target_order in orders) {
+      for (src_pm_alpha in c(TRUE, FALSE)) {
+        for (target_pm_alpha in c(TRUE, FALSE)) {
+          expect_no_error({
+            nr <- nr_duplicate(deer_sprites[[1]])
+            nr_swizzle(nr, order = src_order, pm_alpha = src_pm_alpha, 
+                       target_order = target_order, target_pm_alpha = target_pm_alpha) 
+          })
+        }
+      }
+    }
+  }
+})