From 7856684f76c100155cad11b5b236fb31234b6e28 Mon Sep 17 00:00:00 2001
From: Khem Raj <raj.khem@gmail.com>
Date: Wed, 18 Mar 2015 00:49:28 +0000
Subject: [PATCH] eglibc: Help bootstrap cross toolchain

Taken from EGLIBC, r1484 + r1525

        2007-02-20  Jim Blandy  <jimb@codesourcery.com>

                * Makefile (install-headers): Preserve old behavior: depend on
                $(inst_includedir)/gnu/stubs.h only if install-bootstrap-headers
                is set; otherwise, place gnu/stubs.h on the 'install-others' list.

        2007-02-16  Jim Blandy  <jimb@codesourcery.com>

                * Makefile: Amend make install-headers to install everything
                necessary for building a cross-compiler.  Install gnu/stubs.h as
                part of 'install-headers', not 'install-others'.
                If install-bootstrap-headers is 'yes', install a dummy copy of
                gnu/stubs.h, instead of computing the real thing.
                * include/stubs-bootstrap.h: New file.

Upstream-Status: Pending
Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 Makefile                  | 22 +++++++++++++++++++++-
 include/stubs-bootstrap.h | 12 ++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 include/stubs-bootstrap.h

diff --git a/Makefile b/Makefile
index f98d5a9e67..c36d04da0f 100644
--- a/Makefile
+++ b/Makefile
@@ -79,9 +79,18 @@ subdir-dirs = include
 vpath %.h $(subdir-dirs)
 
 # What to install.
-install-others = $(inst_includedir)/gnu/stubs.h
 install-bin-script =
 
+# If we're bootstrapping, install a dummy gnu/stubs.h along with the
+# other headers, so 'make install-headers' produces a useable include
+# tree.  Otherwise, install gnu/stubs.h later, after the rest of the
+# build is done.
+ifeq ($(install-bootstrap-headers),yes)
+install-headers: $(inst_includedir)/gnu/stubs.h
+else
+install-others = $(inst_includedir)/gnu/stubs.h
+endif
+
 ifeq (yes,$(build-shared))
 headers += gnu/lib-names.h
 endif
@@ -415,6 +424,16 @@ others: $(common-objpfx)testrun.sh $(common-objpfx)debugglibc.sh
 
 subdir-stubs := $(foreach dir,$(subdirs),$(common-objpfx)$(dir)/stubs)
 
+# gnu/stubs.h depends (via the subdir 'stubs' targets) on all the .o
+# files in EGLIBC.  For bootstrapping a GCC/EGLIBC pair, an empty
+# gnu/stubs.h is good enough.
+ifeq ($(install-bootstrap-headers),yes)
+$(inst_includedir)/gnu/stubs.h: include/stubs-bootstrap.h $(+force)
+	$(make-target-directory)
+	$(INSTALL_DATA) $< $@
+
+installed-stubs =
+else
 ifndef abi-variants
 installed-stubs = $(inst_includedir)/gnu/stubs.h
 else
@@ -441,6 +460,7 @@ $(inst_includedir)/gnu/stubs.h: $(+force)
 
 install-others-nosubdir: $(installed-stubs)
 endif
+endif
 
 
 # Since stubs.h is never needed when building the library, we simplify the
diff --git a/include/stubs-bootstrap.h b/include/stubs-bootstrap.h
new file mode 100644
index 0000000000..1d2b669aff
--- /dev/null
+++ b/include/stubs-bootstrap.h
@@ -0,0 +1,12 @@
+/* Placeholder stubs.h file for bootstrapping.
+
+   When bootstrapping a GCC/EGLIBC pair, GCC requires that the EGLIBC
+   headers be installed, but we can't fully build EGLIBC without that
+   GCC.  So we run the command:
+
+      make install-headers install-bootstrap-headers=yes
+
+   to install the headers GCC needs, but avoid building certain
+   difficult headers.  The <gnu/stubs.h> header depends, via the
+   EGLIBC subdir 'stubs' make targets, on every .o file in EGLIBC, but
+   an empty stubs.h like this will do fine for GCC.  */