python/Python-parallel-make.patch

   1 --- misc/Python-2.6.1/Makefile.pre.in.fix-parallel-make 2010-07-22 15:01:39.567996932 -0400
   2 +++ misc/build/Python-2.6.1/Makefile.pre.in     2010-07-22 15:47:02.437998509 -0400
   3 @@ -207,6 +207,7 @@ SIGNAL_OBJS=        @SIGNAL_OBJS@
   4
   5  ##########################################################################
   6  # Grammar
   7 +GRAMMAR_STAMP= $(srcdir)/grammar-stamp
   8  GRAMMAR_H=     $(srcdir)/Include/graminit.h
   9  GRAMMAR_C=     $(srcdir)/Python/graminit.c
  10  GRAMMAR_INPUT= $(srcdir)/Grammar/Grammar
  11 @@ -530,10 +531,24 @@ Modules/getpath.o: $(srcdir)/Modules/get
  12  Modules/python.o: $(srcdir)/Modules/python.c
  13         $(MAINCC) -c $(PY_CFLAGS) -o $@ $(srcdir)/Modules/python.c
  14
  15 +# GNU "make" interprets rules with two dependents as two copies of the rule.
  16 +#
  17 +# In a parallel build this can lead to pgen being run twice, once for each of
  18 +# GRAMMAR_H and GRAMMAR_C, leading to race conditions in which the compiler
  19 +# reads a partially-overwritten copy of one of these files, leading to syntax
  20 +# errors (or linker errors if the fragment happens to be syntactically valid C)
  21 +#
  22 +# See http://www.gnu.org/software/hello/manual/automake/Multiple-Outputs.html
  23 +# for more information
  24 +#
  25 +# Introduce ".grammar-stamp" as a contrived single output from PGEN to avoid
  26 +# this:
  27 +$(GRAMMAR_H) $(GRAMMAR_C): $(GRAMMAR_STAMP)
  28
  29 -$(GRAMMAR_H) $(GRAMMAR_C): $(PGEN) $(GRAMMAR_INPUT)
  30 +$(GRAMMAR_STAMP): $(PGEN) $(GRAMMAR_INPUT)
  31                 -@$(INSTALL) -d Include
  32                 -$(PGEN) $(GRAMMAR_INPUT) $(GRAMMAR_H) $(GRAMMAR_C)
  33 +               touch $(GRAMMAR_STAMP)
  34
  35  $(PGEN):       $(PGENOBJS)
  36                 $(CC) $(OPT) $(LDFLAGS) $(PGENOBJS) $(LIBS) -o $(PGEN)