CLJS-2883: Instrumentation fails compilation with a large number of spec'd functions

When instrumenting, unstrumenting, or checking, we normally evaluate
the suppied form in order to convert it to an (unquoted) symbol or
collection of symbols. In the case that this is all speced vars or all
checkable syms, this quoted list can be large enough to cause eval to
fail. Fortunately, in this special case there is no need to actually
apply eval because we know the list of symbols is the second item in
the form.

Author: mfikes

src/main/cljs/cljs/spec/test/alpha.cljc

@@ -83,6 +83,17 @@ returns the set of all symbols naming vars in those nses."
           [sym])))
     (collectionize sym-or-syms)))
 
+(defn- form->sym-or-syms
+  "Helper for extracting a symbol or symbols from a (potentially
+  user-supplied) quoted form. In the case that the form has ::no-eval meta, we
+  know it was generated by us and we directly extract the result, assuming the
+  shape of the form. This avoids applying eval to extremely large forms in the
+  latter case."
+  [sym-or-syms]
+  (if (::no-eval (meta sym-or-syms))
+    (second sym-or-syms)
+    (eval sym-or-syms)))
+
 (defmacro instrument
   "Instruments the vars named by sym-or-syms, a symbol or collection
 of symbols, or all instrumentable vars if sym-or-syms is not
@@ -122,12 +133,12 @@ invokes the fn you provide, enabling arbitrary stubbing and mocking.
 
 Returns a collection of syms naming the vars instrumented."
   ([]
-   `(instrument '[~@(#?(:clj  s/speced-vars
-                        :cljs cljs.spec.alpha$macros/speced-vars))]))
+   `(instrument ^::no-eval '[~@(#?(:clj  s/speced-vars
+                                   :cljs cljs.spec.alpha$macros/speced-vars))]))
   ([xs]
    `(instrument ~xs nil))
   ([sym-or-syms opts]
-   (let [syms (sym-or-syms->syms (eval sym-or-syms))
+   (let [syms (sym-or-syms->syms (form->sym-or-syms sym-or-syms))
          opts-sym (gensym "opts")]
      `(let [~opts-sym ~opts]
         (reduce
@@ -148,9 +159,9 @@ Returns a collection of syms naming the vars instrumented."
 as in instrument. With no args, unstruments all instrumented vars.
 Returns a collection of syms naming the vars unstrumented."
   ([]
-   `(unstrument '[~@(deref instrumented-vars)]))
+   `(unstrument ^::no-eval '[~@(deref instrumented-vars)]))
   ([sym-or-syms]
-   (let [syms (sym-or-syms->syms (eval sym-or-syms))]
+   (let [syms (sym-or-syms->syms (form->sym-or-syms sym-or-syms))]
      `(reduce
         (fn [ret# f#]
           (let [sym# (f#)]
@@ -256,11 +267,11 @@ spec itself will have an ::s/failure value in ex-data:
 :instrument     invalid args detected by instrument
 "
   ([]
-   `(check '~(checkable-syms*)))
+   `(check ^::no-eval '~(checkable-syms*)))
   ([sym-or-syms]
    `(check ~sym-or-syms nil))
   ([sym-or-syms opts]
-   (let [syms (sym-or-syms->syms (eval sym-or-syms))
+   (let [syms (sym-or-syms->syms (form->sym-or-syms sym-or-syms))
          opts-sym (gensym "opts")]
      `(let [~opts-sym ~opts]
         [~@(->> syms