diff options
| -rw-r--r-- | CONFORMANCE | 30 |
1 files changed, 12 insertions, 18 deletions
diff --git a/CONFORMANCE b/CONFORMANCE index 6872308..8275aba 100644 --- a/CONFORMANCE +++ b/CONFORMANCE @@ -125,7 +125,9 @@ C99 added %a as another scanf format specifier for floating point values. This conflicts with the glibc extension where %as, %a[ and %aS mean to allocate the string for the data read. A strictly conforming C99 program using %as, %a[ or %aS in a scanf format string -will misbehave under glibc. +will misbehave under glibc if it does not include <stdio.h> and +instead declares scanf itself; if it gets the declaration of scanf +from <stdio.h>, it will use a C99-conforming version. Compiler limitations @@ -144,29 +146,21 @@ GCC doesn't support the optional imaginary types. Nor does it understand the keyword _Complex before GCC 3.0. This has the corresponding impact on the relevant headers. -glibc's use of extern inline conflicts with C99: in C99, extern inline -means that an external definition is generated as well as possibly an -inline definition, but in GCC it means that no external definition is -generated. When GCC's C99 mode implements C99 inline semantics, this -will break the uses of extern inline in glibc's headers. (Actually, -glibc uses `extern __inline', which is beyond the scope of the -standard, but it would clearly be very confusing for `__inline' and -plain `inline' to have different meanings in C99 mode.) - glibc's <tgmath.h> implementation is arcane but thought to work correctly; a clean and comprehensible version requires compiler builtins. For most of the headers required of freestanding implementations, glibc relies on GCC to provide correct versions. (At present, glibc -provides <stdint.h>, and GCC doesn't.) - -Implementing MATH_ERRNO, MATH_ERREXCEPT and math_errhandling in -<math.h> needs compiler support: see - -http://sources.redhat.com/ml/libc-hacker/2000-06/msg00008.html -http://sources.redhat.com/ml/libc-hacker/2000-06/msg00014.html -http://sources.redhat.com/ml/libc-hacker/2000-06/msg00015.html +provides <stdint.h>, and GCC doesn't before version 4.5.) + +The definition of math_errhandling conforms so long as no translation +unit using math_errhandling is compiled with -fno-math-errno, +-fno-trapping-math or options such as -ffast-math that imply these +options. math_errhandling is only conditionally defined depending on +__FAST_MATH__; the compiler does not provide the information needed +for more exact definitions based on settings of -fno-math-errno and +-fno-trapping-math, possibly for only some source files in a program. Issues with headers |