[PATCH] c++: Fix Solaris bootstraps across midnight

[Jakub Jelinek <jakub@redhat.com>]

Hi!

When working on the PR109040 fix, I wanted to test it on some
WORD_REGISTER_OPERATIONS target and tried sparc-solaris on GCC Farm.
My bootstrap failed in comparison failure on cp/module.o, because
Solaris date doesn't support the -r option and one stage's cp/module.o
was built before midnight and next stage's cp/module.o after midnight,
so they had different -DMODULE_VERSION= value.

Now, I think the advice (don't bootstrap at midnight) is something
we shouldn't have, so the following patch stores the module version
(still generated through the same way, date -r cp/module.cc
if it works, otherwise just date) into a temporary file, makes sure
that temporary file is updated when cp/module.cc source is updated
and when date -r doesn't work copies file from previous stage
if it is newer than cp/module.cc.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2023-04-11  Jakub Jelinek  <jakub@redhat.com>

	* Make-lang.in (s-cp-module-version): New target.
	(cp/module.o): Depend on it.
	(MODULE_VERSION): Remove variable.
	(CFLAGS-cp/module.o): For -DMODULE_VERSION= argument just
	cat s-cp-module-version.

--- gcc/cp/Make-lang.in.jj	2023-01-16 11:52:16.057734447 +0100
+++ gcc/cp/Make-lang.in	2023-04-06 10:03:34.344469067 +0200
@@ -59,12 +59,21 @@ CFLAGS-cp/module.o += -DHOST_MACHINE=\"$
 
 # In non-release builds, use a date-related module version.
 ifneq ($(DEVPHASE_c),)
-# Some date's don't grok 'r', if so, simply use today's
-# date (don't bootstrap at midnight).
-MODULE_VERSION := $(shell date -r $(srcdir)/cp/module.cc '+%y%m%d-%H%M' \
-  2>/dev/null || date '+%y%m%d-0000' 2>/dev/null || echo 0)
-
-CFLAGS-cp/module.o += -DMODULE_VERSION='($(subst -,,$(MODULE_VERSION))U)'
+# Some date's don't grok 'r', if so, simply use today's date,
+# but use date from previous stage if bootstrapping to avoid breaking
+# bootstraps across midnight.
+s-cp-module-version: $(srcdir)/cp/module.cc
+	MODULE_VERSION=`if date -r $(srcdir)/cp/module.cc '+%y%m%d%H%M' \
+			  2>/dev/null; then :; \
+			elif test ../prev-gcc/s-cp-module-version -nt \
+			       $(srcdir)/cp/module.cc; then \
+			  cat ../prev-gcc/s-cp-module-version; \
+			else \
+			  date '+%y%m%d0000' 2>/dev/null; \
+			fi`; \
+	echo $${MODULE_VERSION}U > s-cp-module-version
+cp/module.o: s-cp-module-version
+CFLAGS-cp/module.o += -DMODULE_VERSION='$(shell cat s-cp-module-version)'
 endif
 
 # Create the compiler driver for g++.

	Jakub