Update to 2025-10-24 google3 version (#465)

* Remove `S2_DEFINE_*` flags macros and use `ABSL_FLAG` directly
* Modernize `ExactFloat` interface
  * Replace `exactfloat::is_nan()` with `isnan(const ExactFloat&)`
  * Replace `ToDouble()` with `explicit operator double()`
  * Add `fpclassify(const ExactFloat&)`
* Add exactfloat_underflow_test
* New `S2Cell::IsDistanceLess` and related predicates
* Do not use `#pragma STDC FP_CONTRACT off` for gcc to try to
  prevent warnings.  gcc has its own pragma (which was always
  used)
* Switch some `ABSL_LOG(ERROR)`s to `DFATAL`

Author: jmr

CMakeLists.txt

@@ -91,7 +91,7 @@ else()
     # match [-Wattributes]
     add_definitions(-Wno-attributes)
     add_definitions(-Wno-deprecated-declarations)
-    # `base/port.h` uses sized deallocation, which should be enabled by
+    # Some files use sized deallocation, which should be enabled by
     # default for C++14 and later.  There appears to be a bug with clang
     # < 19 causing this not to be enabled.
     # https://github.com/google/s2geometry/issues/411#issuecomment-2726949607
@@ -432,11 +432,8 @@ if(S2_ENABLE_INSTALL)
                 src/s2/internal/s2meta.h
           DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/s2/internal")
   install(FILES src/s2/base/casts.h
-                src/s2/base/commandlineflags.h
-                src/s2/base/commandlineflags_declare.h
                 src/s2/base/log_severity.h
                 src/s2/base/malloc_extension.h
-                src/s2/base/port.h
                 src/s2/base/spinlock.h
           DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/s2/base")
   install(FILES src/s2/testing/gtest_prod.h
@@ -622,7 +619,8 @@ if (BUILD_TESTS)
       src/s2/s2wrapped_shape_test.cc
       src/s2/sequence_lexicon_test.cc
       src/s2/value_lexicon_test.cc
-      src/s2/util/math/exactfloat/exactfloat_test.cc)
+      src/s2/util/math/exactfloat/exactfloat_test.cc
+      src/s2/util/math/exactfloat/exactfloat_underflow_test.cc)
 
   enable_testing()
 

doc/examples/point_index.cc

@@ -9,18 +9,18 @@
 #include <random>
 #include <vector>
 
-#include "s2/base/commandlineflags.h"
-#include "s2/s2earth.h"
 #include "absl/flags/flag.h"
 #include "absl/strings/str_format.h"
+
 #include "s2/s1angle.h"
 #include "s2/s2closest_point_query.h"
+#include "s2/s2earth.h"
 #include "s2/s2point_index.h"
 #include "s2/s2random.h"
 
-S2_DEFINE_int32(num_index_points, 10000, "Number of points to index");
-S2_DEFINE_int32(num_queries, 10000, "Number of queries");
-S2_DEFINE_double(query_radius_km, 100, "Query radius in kilometers");
+ABSL_FLAG(int32_t, num_index_points, 10000, "Number of points to index");
+ABSL_FLAG(int32_t, num_queries, 10000, "Number of queries");
+ABSL_FLAG(double, query_radius_km, 100, "Query radius in kilometers");
 
 int main(int argc, char **argv) {
   std::mt19937_64 bitgen;

doc/examples/term_index.cc

@@ -16,23 +16,20 @@
 #include <string>
 #include <vector>
 
-#include "s2/base/commandlineflags.h"
-#include "s2/s2earth.h"
 #include "absl/container/btree_set.h"
 #include "absl/container/flat_hash_map.h"
 #include "absl/flags/flag.h"
 #include "absl/strings/str_format.h"
 #include "s2/s1angle.h"
 #include "s2/s2cap.h"
+#include "s2/s2earth.h"
 #include "s2/s2point.h"
 #include "s2/s2random.h"
 #include "s2/s2region_term_indexer.h"
 
-using std::string;
-
-S2_DEFINE_int32(num_documents, 10000, "Number of documents");
-S2_DEFINE_int32(num_queries, 10000, "Number of queries");
-S2_DEFINE_double(query_radius_km, 100, "Query radius in kilometers");
+ABSL_FLAG(int32_t, num_documents, 10000, "Number of documents");
+ABSL_FLAG(int32_t, num_queries, 10000, "Number of queries");
+ABSL_FLAG(double, query_radius_km, 100, "Query radius in kilometers");
 
 // A prefix added to spatial terms to distinguish them from other index terms
 // (e.g. representing words or phrases).

src/BUILD.bazel

@@ -236,9 +236,7 @@ cc_library(
         "//s2:value_lexicon.h",
     ],
     deps = [
-        "//s2/base:commandlineflags",
         "//s2/base:logging",
-        "//s2/base:port",
         "//s2/base:spinlock",
         "//s2/testing",
         "//s2/util/bitmap",
@@ -387,7 +385,6 @@ cc_library(
     includes = ["src"],
     deps = [
         ":s2",
-        "//s2/base:commandlineflags",
         "//s2/base:timer",
         "@abseil-cpp//absl/base",
         "@abseil-cpp//absl/flags:flag",

src/s2/_fp_contract_off.h

@@ -41,13 +41,14 @@
 // appears before the first non-inline function definition.  It is
 // named with an underscore so that it is included first among the S2 headers.
 
-// Assume all compilers support or ignore the standard pragma.
-#pragma STDC FP_CONTRACT OFF
-
 #if defined(__GNUC__) && !defined(__clang__)
 // GCC defines its own pragma that operates at the function level rather than
 // the statement level.
 #pragma GCC optimize("fp-contract=off")
+#else
+// Assume all other compilers support or ignore the standard pragma.
+// Avoid gcc `-Wunknown-pragmas` warnings by not using this for gcc.
+#pragma STDC FP_CONTRACT OFF
 #endif
 
 #endif  // S2__FP_CONTRACT_OFF_H_

src/s2/base/BUILD

@@ -29,22 +29,6 @@ cc_library(
     ],
 )
 
-cc_library(
-    name = "port",
-    hdrs = ["port.h"],
-)
-
-cc_library(
-    name = "commandlineflags",
-    hdrs = [
-        "commandlineflags.h",
-        "commandlineflags_declare.h",
-    ],
-    deps = [
-        "@abseil-cpp//absl/flags:flag",
-    ],
-)
-
 cc_library(
     name = "timer",
     hdrs = [

src/s2/base/commandlineflags.h

@@ -114,7 +114,7 @@ void EncodeS2PointVector(Span<const S2Point> points, CodingHint hint,
       return EncodeS2PointVectorCompact(points, encoder);
 
     default:
-      ABSL_LOG(ERROR) << "Unknown CodingHint: " << static_cast<int>(hint);
+      ABSL_LOG(DFATAL) << "Unknown CodingHint: " << static_cast<int>(hint);
   }
 }
 
@@ -236,7 +236,7 @@ bool EncodedS2PointVector::InitUncompressedFormat(Decoder* decoder) {
     // Maybe the compiler is smart enough that we can do this all the time,
     // but more likely we will need two cases using the #ifdef above.
     // (Note that even ARMv7 does not support unaligned 64-bit loads.)
-    ABSL_LOG(ERROR)
+    ABSL_LOG(DFATAL)
         << "Needs architecture with 64-bit little-endian unaligned loads";
     return false;
   }

src/s2/base/port.h

@@ -63,7 +63,7 @@ class EncodedS2PointVector {
   //
   // Encoded types do not necessarily read all of their data when calling
   // Init(), instead only data necessary to decode further is read, which means
-  // that encoded types may in general log ERROR errors when reading from an
+  // that encoded types may in general log DFATAL errors when reading from an
   // untrusted byte stream using unchecked accessors (e.g. operator[]).
   //
   // Checked accessors such as Decode(S2Error&) will instead set an error
@@ -182,7 +182,7 @@ inline S2Point EncodedS2PointVector::operator[](int i) const {
   S2Error error;
   S2Point point = At(i, error);
   if (!error.ok()) {
-    ABSL_LOG(ERROR) << error.message();
+    ABSL_LOG(DFATAL) << error.message();
   }
   return point;
 #else