From 5857c056276699c2b7ed1e8cc2a05cc4ff3bde5a Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 27 May 2024 11:04:03 -0700
Subject: [PROPOSED 2/2] * CONTRIBUTING: Document build assumptions.

---
 CONTRIBUTING | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/CONTRIBUTING b/CONTRIBUTING
index 6d800e4c..c8fdf013 100644
--- a/CONTRIBUTING
+++ b/CONTRIBUTING
@@ -63,12 +63,16 @@ If you use Git the following workflow may be helpful:
   * Edit source files.  Include commentary that justifies the
     changes by citing reliable sources.
 
-  * Debug the changes, e.g.:
+  * Debug the changes locally, e.g.:
 
-        make check
-        make install
+        make TOPDIR=$PWD/tz clean check install
         ./zdump -v America/Los_Angeles
 
+    Although builds assume only basic POSIX, they use extra features
+    if available.  'make check' accesses validator.w3.org unless you
+    lack 'curl' or use 'make CURL=:'.  If you have the latest GCC,
+    "make CFLAGS='$(GCC_DEBUG_FLAGS)'" does extra checking.
+
   * For each separable change, commit it in the new branch, e.g.:
 
         git add northamerica
-- 
2.43.0