[gcc r9-8174] libstdc++: Simplify makefile rule for largefile-config.h (PR91947)

[Jonathan Wakely]

https://gcc.gnu.org/g:e2bcf65feea9590e6f260862b3c740b5e803f851

commit r9-8174-ge2bcf65feea9590e6f260862b3c740b5e803f851
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Jan 24 11:13:55 2020 +0000

    libstdc++: Simplify makefile rule for largefile-config.h (PR91947)
    
    The previous rule could leave an incomplete file if the build was
    interrupted, which would then not be remade if make was run again.
    
    This makes the rule more robust by writing to a temporary file and only
    moving it into place as the final step. It also simplifies the rule so
    that only the essential macro definitions are written to the file, not
    the explanatory comments and commented out #undef lines.
    
    Also, the macro for enabling LFS on Mac OS X 10.5 is now set
    unconditionally, which is a bug fix from upstream autoconf.
    
    Backport from mainline
    2020-01-23  Jonathan Wakely  <jwakely@redhat.com>
    
    	PR libstdc++/91947
    	* include/Makefile.am (${host_builddir}/largefile-config.h): Simplify
    	rule.
    	* include/Makefile.in: Regenerate.

Diff:
---
 libstdc++-v3/ChangeLog           |  8 ++++++++
 libstdc++-v3/include/Makefile.am | 22 ++++++----------------
 libstdc++-v3/include/Makefile.in | 22 ++++++----------------
 3 files changed, 20 insertions(+), 32 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 5b25916..60f2101 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,6 +1,14 @@
 2020-01-24  Jonathan Wakely  <jwakely@redhat.com>
 
 	Backport from mainline
+	2020-01-23  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/91947
+	* include/Makefile.am (${host_builddir}/largefile-config.h): Simplify
+	rule.
+	* include/Makefile.in: Regenerate.
+
+	Backport from mainline
 	2020-01-20  Jonathan Wakely  <jwakely@redhat.com>
 
 	* doc/xml/faq.xml: Fix grammar.
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index f4d89db..7958f43 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -1285,22 +1285,12 @@ stamp-float128:
 endif
 
 # This header is not installed, it's only used to build libstdc++ itself.
-${host_builddir}/largefile-config.h: ${CONFIG_HEADER} \
-				     ${glibcxx_srcdir}/include/bits/c++config
-	@echo '#if defined _GLIBCXX_CXX_CONFIG_H || defined _FEATURES_H' > $@
-	@echo '# error "This file must be included before any others"' >> $@
-	@echo '#endif' >> $@
-	@echo >> $@
-	@echo '/* Enable large inode numbers on Mac OS X 10.5.  */' >> $@
-	@echo '#ifndef _DARWIN_USE_64_BIT_INODE' >> $@
-	@echo '# define _DARWIN_USE_64_BIT_INODE 1' >> $@
-	@echo '#endif' >> $@
-	@echo >> $@
-	@echo '/* Number of bits in a file offset, on hosts where this is settable. */' >> $@
-	@grep '_FILE_OFFSET_BITS' ${CONFIG_HEADER} >> $@
-	@echo >> $@
-	@echo '/* Define for large files, on AIX-style hosts. */' >> $@
-	@grep '_LARGE_FILES' ${CONFIG_HEADER} >> $@
+${host_builddir}/largefile-config.h: ${CONFIG_HEADER}
+	@rm -f $@.tmp
+	@-grep 'define _DARWIN_USE_64_BIT_INODE' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _FILE_OFFSET_BITS' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _LARGE_FILES' ${CONFIG_HEADER} >> $@.tmp
+	@mv $@.tmp $@
 
 # NB: The non-empty default ldbl_compat works around an AIX sed
 # oddity, see libstdc++/31957 for details.
diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in
index 40628e1..631c772 100644
--- a/libstdc++-v3/include/Makefile.in
+++ b/libstdc++-v3/include/Makefile.in
@@ -1767,22 +1767,12 @@ stamp-host: ${host_headers} ${bits_host_headers} ${ext_host_headers} ${host_head
 @ENABLE_FLOAT128_FALSE@	echo 'undef _GLIBCXX_USE_FLOAT128' > stamp-float128
 
 # This header is not installed, it's only used to build libstdc++ itself.
-${host_builddir}/largefile-config.h: ${CONFIG_HEADER} \
-				     ${glibcxx_srcdir}/include/bits/c++config
-	@echo '#if defined _GLIBCXX_CXX_CONFIG_H || defined _FEATURES_H' > $@
-	@echo '# error "This file must be included before any others"' >> $@
-	@echo '#endif' >> $@
-	@echo >> $@
-	@echo '/* Enable large inode numbers on Mac OS X 10.5.  */' >> $@
-	@echo '#ifndef _DARWIN_USE_64_BIT_INODE' >> $@
-	@echo '# define _DARWIN_USE_64_BIT_INODE 1' >> $@
-	@echo '#endif' >> $@
-	@echo >> $@
-	@echo '/* Number of bits in a file offset, on hosts where this is settable. */' >> $@
-	@grep '_FILE_OFFSET_BITS' ${CONFIG_HEADER} >> $@
-	@echo >> $@
-	@echo '/* Define for large files, on AIX-style hosts. */' >> $@
-	@grep '_LARGE_FILES' ${CONFIG_HEADER} >> $@
+${host_builddir}/largefile-config.h: ${CONFIG_HEADER}
+	@rm -f $@.tmp
+	@-grep 'define _DARWIN_USE_64_BIT_INODE' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _FILE_OFFSET_BITS' ${CONFIG_HEADER} >> $@.tmp
+	@-grep 'define _LARGE_FILES' ${CONFIG_HEADER} >> $@.tmp
+	@mv $@.tmp $@
 
 # NB: The non-empty default ldbl_compat works around an AIX sed
 # oddity, see libstdc++/31957 for details.