fix(coverage): bind json reader vars dynamically in simplecov parsers

The simplecov parse helpers let-bound json-object-type, json-array-type, and json-key-type around json-read-file to get string-keyed hash tables. Under lexical-binding the compiler hadn't seen json.el's defvars, so it compiled those as lexical bindings that never reached the reader; the compiled helpers got json.el's default symbol-keyed alist and then signaled wrong-type-argument hash-table-p in their maphash. Interpreted code happened to work because the in-function require made the vars special first. Add eval-when-compile (require 'json) so the compiler treats them as dynamic.

Claude-Session: https://claude.ai/code/session_01BqrdWUo9GcznYX2pZr76gZ

1 files changed, 9 insertions, 0 deletions

diff --git a/modules/coverage-core.el b/modules/coverage-core.el
index 9b102bb7b..e8f7a4740 100644
--- a/modules/coverage-core.el
+++ b/modules/coverage-core.el
@@ -25,6 +25,15 @@
 (require 'subr-x)
 (require 'system-lib)
 
+;; Make json.el's reader variables visible to the byte/native compiler so the
+;; `let' bindings of `json-object-type' / `json-array-type' / `json-key-type'
+;; in the parse helpers below bind dynamically.  Without this the compiler
+;; treats them as lexical (this file is lexical-binding), the bindings never
+;; reach `json-read-file', and it returns json.el's default alist instead of
+;; the hash tables the parsers maphash over.  The runtime `(require 'json)'
+;; inside each helper still keeps json off the load-time path.
+(eval-when-compile (require 'json))
+
 (defvar cj/coverage-backends nil
   "Registry of coverage backends in priority order.
 Each entry is a plist with at least :name, :detect, :run, and :report-path.