Track some important design information as tests.

The Go Playground is also often a perfectly good home for these things;
I've also used "_rsrch" directories in other projects, especially if
benchmarks of nontrivial runtime and setup get involved; but this
will suffice for this quick factcheck here and now.

schema/gen/go/info_test.go

+package gengo
+
+import (
+	"testing"
+	"unsafe"
+)
+
+// This file contains some short informative tests that were useful to design.
+// It's stuff that probably would be just as suited to life in the go playground.
+
+func TestUnderstandingStructMemoryLayout(t *testing.T) {
+	t.Skip("This is for human information and not usually necessary to run.")
+
+	// This test informs why the additional bools for optional+nullable fields
+	// in structs are grouped together, even though it makes codegen more fiddly.
+
+	// https://go101.org/article/memory-layout.html also has a nice writeup.
+
+	t.Logf("%d\n", unsafe.Sizeof(struct {
+		x int32
+		y int32
+	}{})) // 8
+	t.Logf("%d\n", unsafe.Sizeof(struct {
+		x int32
+		a bool
+		y int32
+		b bool
+	}{})) // 16 ... !  word alignment.
+	t.Logf("%d\n", unsafe.Sizeof(struct {
+		a bool
+		b bool
+		x int32
+		y int32
+	}{})) // 12.  consecutive bools get packed.
+	t.Logf("%d\n", unsafe.Sizeof(struct {
+		x int32
+		y int32
+		a bool
+		b bool
+	}{})) // 12.  consecutive bool packing works anywhere.
+	t.Logf("%d\n", unsafe.Sizeof(struct {
+		x          int32
+		y          int32
+		a, b, c, d bool
+	}{})) // 12.  bool packing works up to four.
+	t.Logf("%d\n", unsafe.Sizeof(struct {
+		x             int32
+		y             int32
+		a, b, c, d, e bool
+	}{})) // 16 ... !  bools take a byte; the fifth triggers a new word.
+}