Add gcc-backport and support git cherry pick.

* gcc-changelog/git_commit.py: Support cherry pick
	prefix.
	* gcc-changelog/test_email.py: Test it.
	* gcc-changelog/test_patches.txt: Add new patch.
	* gcc-git-customization.sh: Add gcc-backport.

contrib/ChangeLog

@@ -1,3 +1,11 @@
+2020-05-20  Martin Liska  <mliska@suse.cz>
+
+	* gcc-changelog/git_commit.py: Support cherry pick
+	prefix.
+	* gcc-changelog/test_email.py: Test it.
+	* gcc-changelog/test_patches.txt: Add new patch.
+	* gcc-git-customization.sh: Add gcc-backport.
+
 2020-05-19  Martin Liska  <mliska@suse.cz>
 
 	* mklog.py: Use REST API for bug title downloading.

contrib/gcc-changelog/git_commit.py

@@ -150,6 +150,7 @@ star_prefix_regex = re.compile(r'\t\*(?P<spaces>\ *)(?P<content>.*)')
 LINE_LIMIT = 100
 TAB_WIDTH = 8
 CO_AUTHORED_BY_PREFIX = 'co-authored-by: '
+CHERRY_PICK_PREFIX = '(cherry picked from commit '
 
 
 class Error:
@@ -349,6 +350,8 @@ class GitCommit:
                     author = self.format_git_author(name)
                     self.co_authors.append(author)
                     continue
+                elif line.startswith(CHERRY_PICK_PREFIX):
+                    continue
 
                 # ChangeLog name will be deduced later
                 if not last_entry:

contrib/gcc-changelog/test_email.py

@@ -258,3 +258,7 @@ class TestGccChangelog(unittest.TestCase):
         email = self.from_patch_glob('0020-IPA-Avoid')
         assert (email.errors[0].message
                 == 'first line should start with a tab, asterisk and space')
+
+    def test_cherry_pick_format(self):
+        email = self.from_patch_glob('0001-c-Alias.patch')
+        assert not email.errors

contrib/gcc-changelog/test_patches.txt

@@ -2382,3 +2382,32 @@ index 00000000000..66c87d48694
 -- 
 2.26.1
 
+=== 0001-c-Alias.patch ===
+From 3f1a149fc35cdba988464562e2fb824b10652d6b Mon Sep 17 00:00:00 2001
+From: Nathan Sidwell <nathan@acm.org>
+Date: Tue, 19 May 2020 13:29:19 -0700
+Subject: [PATCH] c++: Alias template instantiation template info
+
+I discovered that the alias instantiation machinery would setup
+template_info, and then sometime later overwrite that with equivalent
+info.  This broke modules, because the template info, once set, is
+logically immutable.  Let's just not do that.
+
+	* pt.c (lookup_template_class_1): Do not reinit template_info of an
+	alias here.
+
+(cherry picked from commit 74744bb1f2847b5b9ce3e97e0fec9c23bb0e499f)
+---
+ gcc/cp/pt.c | 17 +++++++++++++++--
+ 1 file changed, 15 insertions(+), 2 deletions(-)
+
+diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
+index b8f03d18541..7230ac724ba 100644
+--- a/gcc/cp/pt.c
++++ b/gcc/cp/pt.c
+@@ -1 +1,2 @@
+
++
+-- 
+2.26.2
+

contrib/gcc-git-customization.sh

@@ -26,6 +26,7 @@ git config alias.gcc-descr \!"f() { if test \${1:-no} = --full; then c=\${2:-mas
 git config alias.gcc-undescr \!"f() { o=\$(git config --get gcc-config.upstream); r=\$(echo \$1 | sed -n 's,^r\\([0-9]\\+\\)-[0-9]\\+\$,\\1,p'); n=\$(echo \$1 | sed -n 's,^r[0-9]\\+-\\([0-9]\\+\\)\$,\\1,p'); test -z \$r && echo Invalid id \$1 && exit 1; h=\$(git rev-parse --verify --quiet \${o:-origin}/releases/gcc-\$r); test -z \$h && h=\$(git rev-parse --verify --quiet \${o:-origin}/master); p=\$(git describe --all --match 'basepoints/gcc-'\$r \$h | sed -n 's,^\\(tags/\\)\\?basepoints/gcc-[0-9]\\+-\\([0-9]\\+\\)-g[0-9a-f]*\$,\\2,p;s,^\\(tags/\\)\\?basepoints/gcc-[0-9]\\+\$,0,p'); git rev-parse --verify \$h~\$(expr \$p - \$n); }; f"
 
 git config alias.gcc-verify '!f() { "`git rev-parse --show-toplevel`/contrib/gcc-changelog/git_check_commit.py" $@; } ; f'
+git config alias.gcc-backport '!f() { rev=$1; git cherry-pick -x $@; } ; f'
 
 git config alias.gcc-mklog '!f() { "`git rev-parse --show-toplevel`/contrib/mklog.py" $@; } ; f'