[PATCH v2] html: Set CONTENTS_OUTPUT_LOCATION=inline if makeinfo supports it

["Arsen Arsenović" <arsen@aarsen.me>]

This flag allows us to restore old (pre-6.8) behavior of the
@{summary,}content commands, so that texi2any continues to emit
summarycontents first.

maintainer-scripts/ChangeLog:

	* update_web_docs_git: Set CONTENTS_OUTPUT_LOCATION=inline in
	order to put @shortcontents above contents.

gcc/ChangeLog:

	* configure.ac: Add check for the Texinfo 6.8
	CONTENTS_OUTPUT_LOCATION customization variable and set it if
	supported.
	* configure: Regenerate.
	* Makefile.in (MAKEINFO_TOC_INLINE_FLAG): New variable.  Set by
	configure.ac to -c CONTENTS_OUTPUT_LOCATION=inline if
	CONTENTS_OUTPUT_LOCATION support is detected, empty otherwise.
	($(build_htmldir)/%/index.html): Pass MAKEINFO_TOC_INLINE_FLAG.
---
Here's an updated version of that patch, for review.  I'm sending it
separately and properly to not accidentally alienate potential
reviewers.

 gcc/Makefile.in                        |  6 ++++-
 gcc/configure                          | 35 ++++++++++++++++++++++++--
 gcc/configure.ac                       | 21 ++++++++++++++++
 maintainer-scripts/update_web_docs_git |  2 +-
 4 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 6001c9e3b55..d8b76d83d68 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -787,6 +787,9 @@ INSTALL_HEADERS=install-headers install-mkheaders
 # Control whether Info documentation is built and installed.
 BUILD_INFO = @BUILD_INFO@
 
+# Control flags for @contents placement in HTML output
+MAKEINFO_TOC_INLINE_FLAG = @MAKEINFO_TOC_INLINE_FLAG@
+
 # Control whether manpages generated by texi2pod.pl can be rebuilt.
 GENERATED_MANPAGES = @GENERATED_MANPAGES@
 
@@ -3461,7 +3464,8 @@ html:: $(HTMLS_BUILD)
 $(build_htmldir)/%/index.html: %.texi
 	$(mkinstalldirs) $(@D)
 	rm -f $(@D)/*
-	$(TEXI2HTML) -I $(abs_docdir) -I $(abs_docdir)/include -o $(@D) $<
+	$(TEXI2HTML) $(MAKEINFO_TOC_INLINE_FLAG) \
+		-I $(abs_docdir) -I $(abs_docdir)/include -o $(@D) $<
 
 # Duplicate entry to handle renaming of gccinstall
 $(build_htmldir)/gccinstall/index.html: $(TEXI_GCCINSTALL_FILES)
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 62bc908b991..120151c474a 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -1242,6 +1242,27 @@ else
 fi
 AC_SUBST(BUILD_INFO)
 
+# Determine whether makeinfo supports the CONTENTS_OUTPUT_LOCATION variable.
+# If it does, we want to pass it to makeinfo in order to restore the old
+# behavior of @{summary,}contents placement.
+MAKEINFO_TOC_INLINE_FLAG=
+AS_IF([test x"$MAKEINFO" != x], [
+  AC_CACHE_CHECK([for CONTENTS_OUTPUT_LOCATION support in $MAKEINFO],
+  		 [gcc_cv_texi_add_toc_inline_flags], [
+    # Detect the unknown variable CONTENTS_OUTPUT_LOCATION warning
+    if "$MAKEINFO" -c CONTENTS_OUTPUT_LOCATION=inline </dev/null 2>&1 \
+       | grep CONTENTS_OUTPUT_LOCATION >/dev/null; then
+      gcc_cv_texi_add_toc_inline_flags=no
+    else
+      gcc_cv_texi_add_toc_inline_flags=yes
+    fi
+  ])
+  if test x"$gcc_cv_texi_add_toc_inline_flags" = xyes; then
+    MAKEINFO_TOC_INLINE_FLAG='-c CONTENTS_OUTPUT_LOCATION=inline'
+  fi
+])
+AC_SUBST([MAKEINFO_TOC_INLINE_FLAG])
+
 # Is pod2man recent enough to regenerate manpages?
 AC_MSG_CHECKING([for recent Pod::Man])
 if (perl -e 'use 1.10 Pod::Man') >/dev/null 2>&1; then
diff --git a/maintainer-scripts/update_web_docs_git b/maintainer-scripts/update_web_docs_git
index 9ded1744df4..c9f14d1a4d1 100755
--- a/maintainer-scripts/update_web_docs_git
+++ b/maintainer-scripts/update_web_docs_git
@@ -169,7 +169,7 @@ for file in $MANUALS; do
     if [ "$file" = "gnat_ugn" ]; then
       includes="$includes -I gcc/gcc/ada -I gcc/gcc/ada/doc/gnat_ugn"
     fi
-    makeinfo --html --css-ref $CSS $includes -o ${file} ${filename}
+    makeinfo --html -c CONTENTS_OUTPUT_LOCATION=inline --css-ref $CSS $includes -o ${file} ${filename}
     tar cf ${file}-html.tar ${file}/*.html
     texi2dvi $includes -o ${file}.dvi ${filename} </dev/null >/dev/null && dvips -o ${file}.ps ${file}.dvi
     texi2pdf $includes -o ${file}.pdf ${filename} </dev/null
-- 
2.39.2