Set print-symbols-bare to t while saving the build cache

This fixes a bug where recipes may contain symbols with positions,
which have a printed representation but no read syntax, causing the
subsequent load of the build cache to fail. Symbols with positions may
be generated during the execution of the byte compiler.

straight.el

@@ -73,6 +73,15 @@
       "Non-nil means calls to ‘message’ are not displayed.
 They are still logged to the *Messages* buffer.")))
 
+;; Not defined before Emacs 29.1
+(eval-and-compile
+  (unless (boundp 'print-symbols-bare)
+    (defvar 'print-symbols-bare nil
+      "A flag to control printing of symbols with position.
+
+If the value is nil, print these objects complete with position.
+Otherwise print just the bare symbol.")))
+
 ;;;; Functions from other packages
 
 ;; `comp'
@@ -4260,11 +4269,15 @@ The name of the cache file is stored in
   (straight--log 'modification-detection "Saving build cache")
   (unless straight-safe-mode
     (with-temp-buffer
-      ;; Prevent mangling of the form being printed in the case that
-      ;; this function was called by an `eval-expression' invocation
-      ;; of `straight-use-package'.
-      (let ((print-level nil)
-            (print-length nil))
+      (let (;; Prevent mangling of the form being printed in the case that
+            ;; this function was called by an `eval-expression' invocation
+            ;; of `straight-use-package'.
+            (print-level nil)
+            (print-length nil)
+            ;; Print symbols with attached positions, which can occur
+            ;; during byte compilation, as bare symbols so they can be
+            ;; read when loading the cache.
+            (print-symbols-bare t))
         ;; The version of the build cache.
         (print straight--build-cache-version (current-buffer))
         ;; Record the current Emacs version. If a different version of