Issue #15819: Fix out-of-tree builds from a readonly source.

Makefile.pre.in

@@ -59,6 +59,8 @@ INSTALL_DATA=	@INSTALL_DATA@
 # Also, making them read-only seems to be a good idea...
 INSTALL_SHARED= ${INSTALL} -m 555
 
+MKDIR_P=	@MKDIR_P@
+
 MAKESETUP=      $(srcdir)/Modules/makesetup
 
 # Compiler options
@@ -223,8 +225,8 @@ IO_OBJS=	\
 
 ##########################################################################
 # Grammar
-GRAMMAR_H=	$(srcdir)/Include/graminit.h
+GRAMMAR_H=	Include/graminit.h
-GRAMMAR_C=	$(srcdir)/Python/graminit.c
+GRAMMAR_C=	Python/graminit.c
 GRAMMAR_INPUT=	$(srcdir)/Grammar/Grammar
 
 
@@ -266,9 +268,9 @@ PGENOBJS=	$(PGENMAIN) $(POBJS) $(PGOBJS)
 
 ##########################################################################
 # AST
-AST_H_DIR=	$(srcdir)/Include
+AST_H_DIR=	Include
 AST_H=		$(AST_H_DIR)/Python-ast.h
-AST_C_DIR=	$(srcdir)/Python
+AST_C_DIR=	Python
 AST_C=		$(AST_C_DIR)/Python-ast.c
 AST_ASDL=	$(srcdir)/Parser/Python.asdl
 
@@ -609,9 +611,11 @@ Parser/tokenizer_pgen.o:	$(srcdir)/Parser/tokenizer.c
 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)
 
 $(AST_C): $(AST_ASDL) $(ASDLGEN_FILES)
+	$(MKDIR_P) $(AST_C_DIR)
 	$(ASDLGEN) -c $(AST_C_DIR) $(AST_ASDL)
 
 Python/compile.o Python/symtable.o Python/ast.o: $(GRAMMAR_H) $(AST_H)

Misc/NEWS

@@ -495,6 +495,9 @@ Tests
 Build
 -----
 
+- Issue #15819: Make sure we can build Python out-of-tree from a readonly
+  source directory.  (Somewhat related to Issue #9860.)
+
 - Issue #15645: Ensure 2to3 grammar pickles are properly installed.
 
 - Issue #15560: Fix building _sqlite3 extension on OS X with an SDK.

configure

@@ -641,6 +641,7 @@ BASECFLAGS
 OPT
 ABIFLAGS
 LN
+MKDIR_P
 INSTALL_DATA
 INSTALL_SCRIPT
 INSTALL_PROGRAM
@@ -5438,6 +5439,48 @@ test -z "$INSTALL_SCRIPT" && INSTALL_SCRIPT='${INSTALL}'
 
 test -z "$INSTALL_DATA" && INSTALL_DATA='${INSTALL} -m 644'
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for a thread-safe mkdir -p" >&5
+$as_echo_n "checking for a thread-safe mkdir -p... " >&6; }
+if test -z "$MKDIR_P"; then
+  if ${ac_cv_path_mkdir+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH$PATH_SEPARATOR/opt/sfw/bin
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_prog in mkdir gmkdir; do
+	 for ac_exec_ext in '' $ac_executable_extensions; do
+	   { test -f "$as_dir/$ac_prog$ac_exec_ext" && $as_test_x "$as_dir/$ac_prog$ac_exec_ext"; } || continue
+	   case `"$as_dir/$ac_prog$ac_exec_ext" --version 2>&1` in #(
+	     'mkdir (GNU coreutils) '* | \
+	     'mkdir (coreutils) '* | \
+	     'mkdir (fileutils) '4.1*)
+	       ac_cv_path_mkdir=$as_dir/$ac_prog$ac_exec_ext
+	       break 3;;
+	   esac
+	 done
+       done
+  done
+IFS=$as_save_IFS
+
+fi
+
+  test -d ./--version && rmdir ./--version
+  if test "${ac_cv_path_mkdir+set}" = set; then
+    MKDIR_P="$ac_cv_path_mkdir -p"
+  else
+    # As a last resort, use the slow shell script.  Don't cache a
+    # value for MKDIR_P within a source directory, because that will
+    # break other packages using the cache if that directory is
+    # removed, or if the value is a relative name.
+    MKDIR_P="$ac_install_sh -d"
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $MKDIR_P" >&5
+$as_echo "$MKDIR_P" >&6; }
+
 
 # Not every filesystem supports hard links
 
@@ -14567,6 +14610,7 @@ gives unlimited permission to copy, distribute and modify it."
 ac_pwd='$ac_pwd'
 srcdir='$srcdir'
 INSTALL='$INSTALL'
+MKDIR_P='$MKDIR_P'
 test -n "\$AWK" || AWK=awk
 _ACEOF
 
@@ -15134,6 +15178,11 @@ ac_abs_srcdir=$ac_abs_top_srcdir$ac_dir_suffix
   [\\/$]* | ?:[\\/]* ) ac_INSTALL=$INSTALL ;;
   *) ac_INSTALL=$ac_top_build_prefix$INSTALL ;;
   esac
+  ac_MKDIR_P=$MKDIR_P
+  case $MKDIR_P in
+  [\\/$]* | ?:[\\/]* ) ;;
+  */*) ac_MKDIR_P=$ac_top_build_prefix$MKDIR_P ;;
+  esac
 _ACEOF
 
 cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
@@ -15188,6 +15237,7 @@ s&@builddir@&$ac_builddir&;t t
 s&@abs_builddir@&$ac_abs_builddir&;t t
 s&@abs_top_builddir@&$ac_abs_top_builddir&;t t
 s&@INSTALL@&$ac_INSTALL&;t t
+s&@MKDIR_P@&$ac_MKDIR_P&;t t
 $ac_datarootdir_hack
 "
 eval sed \"\$ac_sed_extra\" "$ac_file_inputs" | $AWK -f "$ac_tmp/subs.awk" \

configure.ac

@@ -869,6 +869,7 @@ bsdos*|hp*|HP*)
 	fi
 esac
 AC_PROG_INSTALL
+AC_PROG_MKDIR_P
 
 # Not every filesystem supports hard links
 AC_SUBST(LN)