From 6361daa76f55474226cb78551b4a082e9d2c1e35 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Wed, 18 Jun 2025 08:53:46 +0200
Subject: [PATCH] feat: `EQUIV{...}` replaced with `[...]` in the text output
 of common units

---
 docs/users_guide/framework_basics/text_output.md |  8 ++++----
 src/core/include/mp-units/framework/unit.h       |  4 ++--
 test/static/unit_symbol_test.cpp                 | 10 +++++-----
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/docs/users_guide/framework_basics/text_output.md b/docs/users_guide/framework_basics/text_output.md
index c931028b..9c3f02ce 100644
--- a/docs/users_guide/framework_basics/text_output.md
+++ b/docs/users_guide/framework_basics/text_output.md
@@ -304,10 +304,10 @@ std::cout << 1 * rad + 1 * deg << "\n";
 prints:
 
 ```text
-40771 EQUIV{[1/25146 mi], [1/15625 km]}
-108167 EQUIV{[1/50292 mi], [1/57875 nmi]}
-23 EQUIV{[1/5 km/h], [1/18 m/s]}
-183.142 EQUIV{[1/π°], [1/180 rad]}
+40771 [(1/25146 mi), (1/15625 km)]
+108167 [(1/50292 mi), (1/57875 nmi)]
+23 [(1/5 km/h), (1/18 m/s)]
+183.142 [(1/π°), (1/180 rad)]
 ```
 
 Thanks to the above, it might be easier for the user to reason about the magnitude of the resulting
diff --git a/src/core/include/mp-units/framework/unit.h b/src/core/include/mp-units/framework/unit.h
index 0eec635b..aa10d2d7 100644
--- a/src/core/include/mp-units/framework/unit.h
+++ b/src/core/include/mp-units/framework/unit.h
@@ -802,7 +802,7 @@ template<typename CharT, std::output_iterator<CharT> Out, typename U, typename..
 constexpr Out unit_symbol_impl(Out out, const common_unit<U, Rest...>&, const unit_symbol_formatting& fmt,
                                bool negative_power)
 {
-  constexpr std::string_view prefix("EQUIV{");
+  constexpr std::string_view prefix("[");
   constexpr std::string_view separator(", ");
   auto print_unit = [&]<Unit Arg>(Arg) {
     constexpr auto u = get_common_unit_in(common_unit<U, Rest...>{}, Arg{});
@@ -814,7 +814,7 @@ constexpr Out unit_symbol_impl(Out out, const common_unit<U, Rest...>&, const un
     detail::copy(std::begin(separator), std::end(separator), out);
     print_unit(Arg{});
   });
-  *out++ = '}';
+  *out++ = ']';
   return out;
 }
 
diff --git a/test/static/unit_symbol_test.cpp b/test/static/unit_symbol_test.cpp
index 03e44477..dbd4c465 100644
--- a/test/static/unit_symbol_test.cpp
+++ b/test/static/unit_symbol_test.cpp
@@ -204,13 +204,13 @@ static_assert(unit_symbol(mag<2> / (mag<π> * mag<e>)*one) == "(2 e⁻¹ π⁻¹
 static_assert(unit_symbol<usf{.solidus = always}>(mag<2> / (mag<π> * mag<e>)*one) == "(2/(e π))");
 
 // common units
-static_assert(unit_symbol(get_common_unit(kilo<metre>, mile)) == "EQUIV{(1/25146 mi), (1/15625 km)}");
-static_assert(unit_symbol(get_common_unit(kilo<metre> / hour, metre / second)) == "EQUIV{(1/5 km/h), (1/18 m/s)}");
+static_assert(unit_symbol(get_common_unit(kilo<metre>, mile)) == "[(1/25146 mi), (1/15625 km)]");
+static_assert(unit_symbol(get_common_unit(kilo<metre> / hour, metre / second)) == "[(1/5 km/h), (1/18 m/s)]");
 static_assert(unit_symbol(get_common_unit(kilo<metre> / hour, metre / second) / second) ==
-              "EQUIV{(1/5 km/h), (1/18 m/s)}/s");
+              "[(1/5 km/h), (1/18 m/s)]/s");
 static_assert(unit_symbol(get_common_unit(kilo<metre> / hour, metre / second) * second) ==
-              "EQUIV{(1/5 km/h), (1/18 m/s)} s");
-static_assert(unit_symbol(get_common_unit(radian, degree)) == "EQUIV{(1/π°), (1/180 rad)}");
+              "[(1/5 km/h), (1/18 m/s)] s");
+static_assert(unit_symbol(get_common_unit(radian, degree)) == "[(1/π°), (1/180 rad)]");
 
 // derived units
 static_assert(unit_symbol(one) == "");  // NOLINT(readability-container-size-empty)