Fix large shift in uint128_fallback

fmtlib · Jul 10, 2022 · 2a1b3ac · 2a1b3ac
1 parent e1d3d3a
commit 2a1b3ac
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Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/include/fmt/format.h b/include/fmt/format.h
@@ -366,10 +366,12 @@ class uint128_fallback {
   }
   FMT_CONSTEXPR auto operator>>(int shift) const -> uint128_fallback {
     if (shift == 64) return {0, hi_};
+    if (shift > 64) return uint128_fallback(0, hi_) >> (shift - 64);
     return {hi_ >> shift, (hi_ << (64 - shift)) | (lo_ >> shift)};
   }
   FMT_CONSTEXPR auto operator<<(int shift) const -> uint128_fallback {
     if (shift == 64) return {lo_, 0};
+    if (shift > 64) return uint128_fallback(lo_, 0) << (shift - 64);
     return {hi_ << shift | (lo_ >> (64 - shift)), (lo_ << shift)};
   }
   FMT_CONSTEXPR auto operator>>=(int shift) -> uint128_fallback& {

diff --git a/test/format-test.cc b/test/format-test.cc
@@ -59,6 +59,8 @@ TEST(uint128_test, shift) {
   EXPECT_EQ(static_cast<uint64_t>(n), 0x8000000000000000);
   n = n >> 62;
   EXPECT_EQ(static_cast<uint64_t>(n), 42);
+  EXPECT_EQ(uint128_fallback(1) << 112, uint128_fallback(0x1000000000000, 0));
+  EXPECT_EQ(uint128_fallback(0x1000000000000, 0) >> 112, uint128_fallback(1));
 }
 
 TEST(uint128_test, minus) {
@@ -234,7 +236,7 @@ TEST(util_test, format_system_error) {
     throws_on_alloc = true;
   }
   if (!throws_on_alloc) {
-    fmt::print("warning: std::allocator allocates {} chars", max_size);
+    fmt::print("warning: std::allocator allocates {} chars\n", max_size);
     return;
   }
 }