[libcxx-commits] [PATCH] D138195: [libc++] Fix __regex_word value when using newlib/picolibc

[Alexander Richardson via Phabricator via libcxx-commits]

arichardson created this revision.
arichardson added reviewers: libc++, michaelplatings.
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arichardson requested review of this revision.
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The ctype mask for newlib/picolibc is fully saturated, so __regex_word
has to overlap with one of the values. This commit uses the same workaround
as bionic did (uint16_t for char_class_type inside regex_traits). It
should be possible to have libc++ provide the default rune table instead,
but that will require a new mechanism to detect newlib inside __config
since the header defining the newlib/picolibc macros has not been included
yet inside __config. This also avoids duplicating the ctype table for
newlib, reducing the global data size.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D138195

Files:
  libcxx/include/__locale
  libcxx/include/regex


Index: libcxx/include/regex
===================================================================
--- libcxx/include/regex
+++ libcxx/include/regex
@@ -1026,7 +1026,7 @@
     typedef _CharT                  char_type;
     typedef basic_string<char_type> string_type;
     typedef locale                  locale_type;
-#ifdef __BIONIC__
+#if defined(__BIONIC__) || defined(_NEWLIB_VERSION)
     // Originally bionic's ctype_base used its own ctype masks because the
     // builtin ctype implementation wasn't in libc++ yet. Bionic's ctype mask
     // was only 8 bits wide and already saturated, so it used a wider type here
@@ -1035,6 +1035,11 @@
     // implementation, but this was not updated to match. Since then Android has
     // needed to maintain a stable libc++ ABI, and this can't be changed without
     // an ABI break.
+    // We also need this workaround for newlib since _NEWLIB_VERSION is not
+    // defined yet inside __config, so we can't set the
+    // _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE macro. Additionally, newlib is
+    // often used for space constrained environments, so it makes sense not to
+    // duplicate the ctype table.
     typedef uint16_t char_class_type;
 #else
     typedef ctype_base::mask        char_class_type;
Index: libcxx/include/__locale
===================================================================
--- libcxx/include/__locale
+++ libcxx/include/__locale
@@ -512,7 +512,8 @@
     static const mask punct  = _P;
     static const mask xdigit = _X | _N;
     static const mask blank  = _B;
-    static const mask __regex_word = 0x80;
+    // mask is already fully saturated, use a different type in regex_type_traits.
+    static const unsigned short __regex_word = 0x100;
 # define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_PRINT
 # define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_ALPHA
 # define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_XDIGIT
@@ -551,7 +552,8 @@
 
     _LIBCPP_INLINE_VISIBILITY ctype_base() {}
 
-    static_assert((__regex_word & ~(space | print | cntrl | upper | lower | alpha | digit | punct | xdigit | blank)) == __regex_word,
+    static_assert((__regex_word & ~(std::make_unsigned<mask>::type)(space | print | cntrl | upper | lower | alpha |
+                                                                    digit | punct | xdigit | blank)) == __regex_word,
                   "__regex_word can't overlap other bits");
 };
 


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