libstdc++: Inline all basic_string::compare overloads [PR59048]

Defining the compare member functions inline allows calls to
traits_type::length and std::min to be inlined, taking advantage of
constant expression arguments. When not inline, the compiler prefers to
use the explicit instantiation definitions in libstdc++.so and can't
take advantage of constant arguments.

libstdc++-v3/ChangeLog:

	PR libstdc++/59048
	* include/bits/basic_string.h (compare): Define inline.
	* include/bits/basic_string.tcc (compare): Remove out-of-line
	definitions.
	* include/bits/cow_string.h (compare): Define inline.
	* testsuite/21_strings/basic_string/operations/compare/char/3.cc:
	New test.

1 files changed, 7 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/compare/char/3.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/compare/char/3.cc
new file mode 100644
index 00000000000..8d2917c5145
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/compare/char/3.cc
@@ -0,0 +1,7 @@
+// { dg-options "-O1 -g0" }
+// { dg-do compile }
+// { dg-final { scan-assembler-not "12basic_stringIcSt11char_traitsIcESaIcEE7compare" } }
+
+#include <string>
+bool eq() { return std::string("blah") == "literal"; }
+bool lt() { return std::string("blah") < "literal"; }