Avoid evaluating quoted f-strings

Fixes #1844.

hy/compiler.py

@@ -606,7 +606,13 @@ class HyASTCompiler(object):
 
         elif isinstance(form, HyString):
             if form.is_format:
-                body.extend([HyKeyword("is_format"), form.is_format])
+                # Ensure that this f-string isn't evaluated right now.
+                body = [
+                    copy.copy(form),
+                    HyKeyword("is_format"),
+                    form.is_format,
+                ]
+                body[0].is_format = False
             if form.brackets is not None:
                 body.extend([HyKeyword("brackets"), form.brackets])
 

tests/native_tests/language.hy

@@ -1303,7 +1303,16 @@ cee\"} dee" "ey bee\ncee dee"))
   ; Format bracket strings
   (assert (= #[f[a{p !r :9}]f] "a'xyzzy'  "))
   (assert (= #[f-string[result: {value :{width}.{precision}}]f-string]
-    "result:      12.34")))
+    "result:      12.34"))
+
+  ; Quoting shouldn't evaluate the f-string immediately
+  ; https://github.com/hylang/hy/issues/1844
+  (setv quoted 'f"hello {world}")
+  (assert quoted.is-format)
+  (with [(pytest.raises NameError)]
+    (eval quoted))
+  (setv world "goodbye")
+  (assert (= (eval quoted) "hello goodbye")))
 
 
 (defn test-import-syntax []