LWG3834 Missing constexpr for std::intmax_t math functions in <cinttypes>

Author: burblebee

source/iostreams.tex

@@ -18515,15 +18515,15 @@
 namespace std {
   using imaxdiv_t = @\seebelow@;
 
-  intmax_t imaxabs(intmax_t j);
-  imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
+  constexpr intmax_t imaxabs(intmax_t j);
+  constexpr imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
   intmax_t strtoimax(const char* nptr, char** endptr, int base);
   uintmax_t strtoumax(const char* nptr, char** endptr, int base);
   intmax_t wcstoimax(const wchar_t* nptr, wchar_t** endptr, int base);
   uintmax_t wcstoumax(const wchar_t* nptr, wchar_t** endptr, int base);
 
-  intmax_t abs(intmax_t);               // optional, see below
-  imaxdiv_t div(intmax_t, intmax_t);    // optional, see below
+  constexpr intmax_t abs(intmax_t);             // optional, see below
+  constexpr imaxdiv_t div(intmax_t, intmax_t);  // optional, see below
 }
 
 #define PRId@\placeholdernc{N}@ @\seebelow@
@@ -18595,12 +18595,12 @@
 if and only if the type \tcode{intmax_t} designates an extended integer
 type\iref{basic.fundamental}, the following function signatures are added:
 \begin{codeblock}
-intmax_t abs(intmax_t);
-imaxdiv_t div(intmax_t, intmax_t);
+constexpr intmax_t abs(intmax_t);
+constexpr imaxdiv_t div(intmax_t, intmax_t);
 \end{codeblock}
 which shall have the same semantics as the function signatures
-\tcode{intmax_t imaxabs(intmax_t)} and
-\tcode{imaxdiv_t imaxdiv(intmax_t, intmax_t)}, respectively.
+\tcode{constexpr intmax_t imaxabs(intmax_t)} and
+\tcode{constexpr imaxdiv_t imaxdiv(intmax_t, intmax_t)}, respectively.
 \end{itemize}
 
 \xrefc{7.8}