[libc++][format] Adds ABI tags to inline constexpr variables.

libcxx/include/__config

@@ -805,6 +805,12 @@ typedef __char32_t char32_t;
 // the implementation of a virtual function in an ABI-incompatible way in the first place,
 // since that would be an ABI break anyway. Hence, the lack of ABI tag should not be noticeable.
 //
+// The macro can be applied to record and enum types. When the tagged type is nested in
+// a record this "parent" record needs to have the macro too. Another use case for applying
+// this macro to records and unions is to apply an ABI tag to inline constexpr variables.
+// This can be useful for inline variables that are implementation details which are expected
+// to change in the future.
+//
 // TODO: We provide a escape hatch with _LIBCPP_NO_ABI_TAG for folks who want to avoid increasing
 //       the length of symbols with an ABI tag. In practice, we should remove the escape hatch and
 //       use compression mangling instead, see https://github.com/itanium-cxx-abi/cxx-abi/issues/70.

libcxx/include/__format/escaped_output_table.h

@@ -110,7 +110,7 @@ namespace __escaped_output_table {
 /// - bits [0, 10] The size of the range, allowing 2048 elements.
 /// - bits [11, 31] The lower bound code point of the range. The upper bound of
 ///   the range is lower bound + size.
-inline constexpr uint32_t __entries[893] = {
+_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[893] = {
     0x00000020,
     0x0003f821,
     0x00056800,

libcxx/include/__format/extended_grapheme_cluster_table.h

@@ -125,7 +125,7 @@ enum class __property : uint8_t {
 /// following benchmark.
 /// libcxx/benchmarks/std_format_spec_string_unicode.bench.cpp
 // clang-format off
-inline constexpr uint32_t __entries[1496] = {
+_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[1496] = {
     0x00000091,
     0x00005005,
     0x00005811,

libcxx/include/__format/parser_std_format_spec.h

@@ -129,8 +129,7 @@ _LIBCPP_HIDE_FROM_ABI constexpr uint32_t __substitute_arg_id(basic_format_arg<_C
 ///
 /// They default to false so when a new field is added it needs to be opted in
 /// explicitly.
-// TODO FMT Use an ABI tag for this struct.
-struct __fields {
+struct _LIBCPP_HIDE_FROM_ABI __fields {
   uint16_t __sign_                 : 1 {false};
   uint16_t __alternate_form_       : 1 {false};
   uint16_t __zero_padding_         : 1 {false};

libcxx/include/__format/width_estimation_table.h

@@ -119,7 +119,7 @@ namespace __width_estimation_table {
 /// - bits [0, 13] The size of the range, allowing 16384 elements.
 /// - bits [14, 31] The lower bound code point of the range. The upper bound of
 ///   the range is lower bound + size.
-inline constexpr uint32_t __entries[108] = {
+_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[108] = {
     0x0440005f /* 00001100 - 0000115f [   96] */, //
     0x08c68001 /* 0000231a - 0000231b [    2] */, //
     0x08ca4001 /* 00002329 - 0000232a [    2] */, //

libcxx/utils/generate_escaped_output_table.py

@@ -124,7 +124,7 @@ def compactPropertyRanges(input: list[PropertyRange]) -> list[PropertyRange]:
 /// - bits [0, 10] The size of the range, allowing 2048 elements.
 /// - bits [11, 31] The lower bound code point of the range. The upper bound of
 ///   the range is lower bound + size.
-inline constexpr uint32_t __entries[{size}] = {{
+_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[{size}] = {{
 {entries}}};
 
 /// At the end of the valid Unicode code points space a lot of code points are

libcxx/utils/generate_extended_grapheme_cluster_table.py

@@ -113,7 +113,7 @@ def compactPropertyRanges(input: list[PropertyRange]) -> list[PropertyRange]:
 /// following benchmark.
 /// libcxx/benchmarks/std_format_spec_string_unicode.bench.cpp
 // clang-format off
-inline constexpr uint32_t __entries[{size}] = {{
+_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[{size}] = {{
 {entries}}};
 // clang-format on
 

libcxx/utils/generate_width_estimation_table.py

@@ -143,7 +143,7 @@ def compactPropertyRanges(input: list[PropertyRange]) -> list[PropertyRange]:
 /// - bits [0, 13] The size of the range, allowing 16384 elements.
 /// - bits [14, 31] The lower bound code point of the range. The upper bound of
 ///   the range is lower bound + size.
-inline constexpr uint32_t __entries[{size}] = {{
+_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[{size}] = {{
 {entries}}};
 
 /// The upper bound entry of EastAsianWidth.txt.