bpo-36733: Fix PYTHONPATH for make regen-add (GH-12969)

Add PYTHONPATH=$(srcdir) to run $(PYTHON_FOR_REGEN) -m Parser.pgen,
so it's possible to build Python from a different directory.

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 68ac7723556e4e980f743ec2af2fba57c5a78e95..d06ad0bc939c35fc5dfc7dd37400a23baa8d7b51 100644 (file)
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -791,7 +791,7 @@ regen-grammar: regen-token
        # Regenerate Include/graminit.h and Python/graminit.c
        # from Grammar/Grammar using pgen
        @$(MKDIR_P) Include
-       $(PYTHON_FOR_REGEN) -m Parser.pgen $(srcdir)/Grammar/Grammar \
+       PYTHONPATH=$(srcdir) $(PYTHON_FOR_REGEN) -m Parser.pgen $(srcdir)/Grammar/Grammar \
                $(srcdir)/Grammar/Tokens \
                $(srcdir)/Include/graminit.h.new \
                $(srcdir)/Python/graminit.c.new
@@ -849,7 +849,7 @@ regen-token:
 regen-keyword:
        # Regenerate Lib/keyword.py from Grammar/Grammar and Grammar/Tokens
        # using Parser/pgen
-       $(PYTHON_FOR_REGEN) -m Parser.pgen.keywordgen $(srcdir)/Grammar/Grammar \
+       PYTHONPATH=$(srcdir) $(PYTHON_FOR_REGEN) -m Parser.pgen.keywordgen $(srcdir)/Grammar/Grammar \
                $(srcdir)/Grammar/Tokens \
                $(srcdir)/Lib/keyword.py.new
        $(UPDATE_FILE) $(srcdir)/Lib/keyword.py $(srcdir)/Lib/keyword.py.new