Closes #21480: better explanation of "hg touch" in the Makefile.

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 629835d16d84120900ccc4d03cd1d583f010a487..70db601e74140dda58bb7f32657c10de8d724954 100644 (file)
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -336,7 +336,8 @@ AST_C=              $(AST_C_DIR)/Python-ast.c
 AST_ASDL=      $(srcdir)/Parser/Python.asdl
 
 ASDLGEN_FILES= $(srcdir)/Parser/asdl.py $(srcdir)/Parser/asdl_c.py
-# XXX Note that a build now requires Python exist before the build starts
+# Note that a build now requires Python to exist before the build starts.
+# Use "hg touch" to fix up screwed up file mtimes in a checkout.
 ASDLGEN=       @ASDLGEN@ $(srcdir)/Parser/asdl_c.py
 
 ##########################################################################
@@ -1500,7 +1501,10 @@ TAGS::
        etags Include/*.h; \
        for i in $(SRCDIRS); do etags -a $$i/*.[ch]; done
 
-# Touch generated files
+# This fixes up the mtimes of checked-in generated files, assuming that they
+# only *appear* to be outdated because of checkout order.
+# This is run while preparing a source release tarball, and can be run manually
+# to avoid bootstrap issues.
 touch:
        cd $(srcdir); \
        hg --config extensions.touch=Tools/hg/hgtouch.py touch -v