From 358fd42aabec56e471ed3c8e6f3dccbc305ff6f7 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 23 Jan 2024 14:57:15 +0000
Subject: [PATCH] libstdc++: Add "ASCII" as an alias for
std::text_encoding::id::ASCII
As noted in LWG 4043, "ASCII" is not an alias for any known registered
character encoding, so std::text_encoding("ASCII").mib() == id::other.
Add the alias "ASCII" to the implementation-defined superset of aliases
for that encoding.
libstdc++-v3/ChangeLog:
* include/bits/text_encoding-data.h: Regenerate.
* scripts/gen_text_encoding_data.py: Add extra_aliases dict
containing "ASCII".
* testsuite/std/text_encoding/cons.cc: Check "ascii" is known.
Co-authored-by: Ewan Higgs <ewan.higgs@gmail.com>
Signed-off-by: Ewan Higgs <ewan.higgs@gmail.com>
---
.../include/bits/text_encoding-data.h | 3 ++-
.../scripts/gen_text_encoding_data.py | 24 ++++++++++++++++++-
.../testsuite/std/text_encoding/cons.cc | 5 ++++
3 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/libstdc++-v3/include/bits/text_encoding-data.h b/libstdc++-v3/include/bits/text_encoding-data.h
index 7ac2e9dc3d92..5041e738d214 100644
--- a/libstdc++-v3/include/bits/text_encoding-data.h
+++ b/libstdc++-v3/include/bits/text_encoding-data.h
@@ -14,6 +14,7 @@
{ 3, "IBM367" },
{ 3, "cp367" },
{ 3, "csASCII" },
+ { 3, "ASCII" }, // libstdc++ extension
{ 4, "ISO_8859-1:1987" },
{ 4, "iso-ir-100" },
{ 4, "ISO_8859-1" },
@@ -417,7 +418,7 @@
{ 104, "csISO2022CN" },
{ 105, "ISO-2022-CN-EXT" },
{ 105, "csISO2022CNEXT" },
-#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET 413
+#define _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET 414
{ 106, "UTF-8" },
{ 106, "csUTF8" },
{ 109, "ISO-8859-13" },
diff --git a/libstdc++-v3/scripts/gen_text_encoding_data.py b/libstdc++-v3/scripts/gen_text_encoding_data.py
index 2d6f3e4077a4..f0ebb42d8c20 100755
--- a/libstdc++-v3/scripts/gen_text_encoding_data.py
+++ b/libstdc++-v3/scripts/gen_text_encoding_data.py
@@ -36,6 +36,18 @@ print("#ifndef _GLIBCXX_GET_ENCODING_DATA")
print('# error "This is not a public header, do not include it directly"')
print("#endif\n")
+# We need to generate a list of initializers of the form { mib, alias }, e.g.,
+# { 3, "US-ASCII" },
+# { 3, "ISO646-US" },
+# { 3, "csASCII" },
+# { 4, "ISO_8859-1:1987" },
+# { 4, "latin1" },
+# The initializers must be sorted by the mib value. The first entry for
+# a given mib must be the primary name for the encoding. Any aliases for
+# the encoding come after the primary name.
+# We also define a macro _GLIBCXX_TEXT_ENCODING_UTF8_OFFSET which is the
+# offset into the list of the mib=106, alias="UTF-8" entry. This is used
+# to optimize the common case, so we don't need to search for "UTF-8".
charsets = {}
with open(sys.argv[1], newline='') as f:
@@ -52,10 +64,15 @@ with open(sys.argv[1], newline='') as f:
aliases.remove(name)
charsets[mib] = [name] + aliases
-# Remove "NATS-DANO" and "NATS-DANO-ADD"
+# Remove "NATS-DANO" and "NATS-DANO-ADD" as specified by the C++ standard.
charsets.pop(33, None)
charsets.pop(34, None)
+# This is not an official IANA alias, but we include it in the
+# implementation-defined superset of aliases for US-ASCII.
+# See also LWG 4043.
+extra_aliases = {3: ["ASCII"]}
+
count = 0
for mib in sorted(charsets.keys()):
names = charsets[mib]
@@ -64,6 +81,11 @@ for mib in sorted(charsets.keys()):
for name in names:
print(' {{ {:4}, "{}" }},'.format(mib, name))
count += len(names)
+ if mib in extra_aliases:
+ names = extra_aliases[mib]
+ for name in names:
+ print(' {{ {:4}, "{}" }}, // libstdc++ extension'.format(mib, name))
+ count += len(names)
# <text_encoding> gives an error if this macro is left defined.
# Do this last, so that the generated output is not usable unless we reach here.
diff --git a/libstdc++-v3/testsuite/std/text_encoding/cons.cc b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
index b9d93641de44..8fcc2ec8c3b9 100644
--- a/libstdc++-v3/testsuite/std/text_encoding/cons.cc
+++ b/libstdc++-v3/testsuite/std/text_encoding/cons.cc
@@ -53,6 +53,11 @@ test_construct_by_name()
VERIFY( e4.name() == s );
VERIFY( ! e4.aliases().empty() );
VERIFY( e4.aliases().front() == "US-ASCII"sv ); // primary name
+
+ s = "ascii";
+ std::text_encoding e5(s);
+ VERIFY( e5.mib() == std::text_encoding::ASCII );
+ VERIFY( e5.name() == s );
}
constexpr void
--
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