# HG changeset patch
# Parent  9cabcb4411acac5ff1397e11fd84cae756c8e405
Issue #23404: Add make BOOT="#" option to disable regenerating existing files

diff -r 9cabcb4411ac Makefile.pre.in
--- a/Makefile.pre.in	Tue Sep 13 11:41:45 2016 +0000
+++ b/Makefile.pre.in	Tue Sep 13 11:55:31 2016 +0000
@@ -218,6 +218,10 @@
 COVERAGE_REPORT=$(abs_builddir)/lcov-report
 COVERAGE_REPORT_OPTIONS=--no-branch-coverage --title "CPython lcov report"
 
+# Run <make BOOT="#"> to avoid regenerating existing files, as an
+# alternative to the "make touch" rule.
+BOOT=
+
 # === Definitions added by makesetup ===
 
 
@@ -680,10 +684,10 @@
 Modules/pwdmodule.o: $(srcdir)/Modules/pwdmodule.c $(srcdir)/Modules/posixmodule.h
 
 $(GRAMMAR_H): @GENERATED_COMMENT@ $(GRAMMAR_INPUT) $(PGEN)
-	@$(MKDIR_P) Include
-	$(PGEN) $(GRAMMAR_INPUT) $(GRAMMAR_H) $(GRAMMAR_C)
+	@$(BOOT)$(MKDIR_P) Include
+	$(BOOT)$(PGEN) $(GRAMMAR_INPUT) $(GRAMMAR_H) $(GRAMMAR_C)
 $(GRAMMAR_C): @GENERATED_COMMENT@ $(GRAMMAR_H)
-	touch $(GRAMMAR_C)
+	$(BOOT)touch $(GRAMMAR_C)
 
 $(PGEN):	$(PGENOBJS)
 		$(CC) $(OPT) $(LDFLAGS) $(PGENOBJS) $(LIBS) -o $(PGEN)
@@ -698,12 +702,12 @@
 Parser/pgenmain.o:	$(srcdir)/Include/parsetok.h
 
 $(AST_H): $(AST_ASDL) $(ASDLGEN_FILES)
-	$(MKDIR_P) $(AST_H_DIR)
-	$(ASDLGEN) -h $(AST_H_DIR) $(AST_ASDL)
+	$(BOOT)$(MKDIR_P) $(AST_H_DIR)
+	$(BOOT)$(ASDLGEN) -h $(AST_H_DIR) $(AST_ASDL)
 
 $(AST_C): $(AST_ASDL) $(ASDLGEN_FILES)
-	$(MKDIR_P) $(AST_C_DIR)
-	$(ASDLGEN) -c $(AST_C_DIR) $(AST_ASDL)
+	$(BOOT)$(MKDIR_P) $(AST_C_DIR)
+	$(BOOT)$(ASDLGEN) -c $(AST_C_DIR) $(AST_ASDL)
 
 Python/compile.o Python/symtable.o Python/ast.o: $(GRAMMAR_H) $(AST_H)
 
@@ -741,7 +745,7 @@
 				$(STRINGLIB_HEADERS)
 
 $(OPCODETARGETS_H): $(OPCODETARGETGEN_FILES)
-	$(OPCODETARGETGEN) $(OPCODETARGETS_H)
+	$(BOOT)$(OPCODETARGETGEN) $(OPCODETARGETS_H)
 
 Python/ceval.o: $(OPCODETARGETS_H)
 
@@ -1376,7 +1380,7 @@
 	etags Include/*.h; \
 	for i in $(SRCDIRS); do etags -a $$i/*.[ch]; done
 
-# Touch generated files
+# Touch generated files.  Alternative to setting BOOT="#".
 touch:
 	cd $(srcdir); \
 	touch Include/Python-ast.h Python/Python-ast.c