Fix the handling of dot expressions with ""

Author: Kodiologist

NEWS.rst

@@ -9,6 +9,10 @@ New Features
 ------------------------------
 * New pragma `hy`.
 
+Bug Fixes
+------------------------------
+* Fixed a crash from using an empty string in a `(. …)` expression.
+
 1.0.0 ("Afternoon Review", released 2024-09-22)
 ======================================================================
 

hy/macros.py

@@ -357,7 +357,11 @@ def macroexpand(tree, module, compiler=None, once=False, result_ok=True):
     while isinstance(tree, Expression) and tree:
 
         fn = tree[0]
-        if isinstance(fn, Expression) and fn and fn[0] == Symbol("."):
+        if (
+                isinstance(fn, Expression) and
+                fn and
+                fn[0] == Symbol(".") and
+                all(isinstance(x, Symbol) for x in fn)):
             fn = ".".join(map(mangle, fn[1:]))
         elif isinstance(fn, Symbol):
             fn = mangle(fn)

tests/native_tests/dots.hy

@@ -35,6 +35,14 @@
   (assert (= (.__str__ :foo) ":foo")))
 
 
+(defn test-dot-empty-string []
+  ; https://github.com/hylang/hy/issues/2625
+  (assert (=
+    ((. "" join) ["aa" "bb" "cc"])
+    (.join "" ["aa" "bb" "cc"])
+    "aabbcc")))
+
+
 (defn test-dot-macro []
   (defclass mycls [object])