[PATCH] intprops: new public macro EXPR_SIGNED

[Paul Eggert]

Emacs can use this macro, so make it public.
* doc/intprops.texi (Arithmetic Type Properties): Rename from
'Integer Type Determination', since some of these macros apply
to non-integer types.  Clarify what kinds of constant expressions
these macros return.  Say when the arguments can be non-integers.
Mention newly published macro EXPR_SIGNED.
* lib/intprops.h (EXPR_SIGNED): Rename from _GL_INT_SIGNED, to
make it public.  All uses changed.
---
 ChangeLog         | 10 ++++++++++
 doc/intprops.texi | 27 +++++++++++++++++++++------
 lib/intprops.h    | 17 ++++++++---------
 3 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 96fd547..7bfce97 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
 2015-11-10  Paul Eggert  <address@hidden>
 
+       intprops: new public macro EXPR_SIGNED
+       Emacs can use this macro, so make it public.
+       * doc/intprops.texi (Arithmetic Type Properties): Rename from
+       'Integer Type Determination', since some of these macros apply
+       to non-integer types.  Clarify what kinds of constant expressions
+       these macros return.  Say when the arguments can be non-integers.
+       Mention newly published macro EXPR_SIGNED.
+       * lib/intprops.h (EXPR_SIGNED): Rename from _GL_INT_SIGNED, to
+       make it public.  All uses changed.
+
        intprops: fix typo in clang port
        * lib/intprops.h (_GL_INT_OP_WRAPV): Fix misspelling of
        '__builtin_add_overflow' that is not caught by compiler.
diff --git a/doc/intprops.texi b/doc/intprops.texi
index 55e60e9..732010c 100644
--- a/doc/intprops.texi
+++ b/doc/intprops.texi
@@ -43,37 +43,52 @@ is easier to use, while the second, for integer ranges, has 
a simple
 and straightforward portable implementation.
 
 @menu
-* Integer Type Determination::  Whether a type has integer properties.
+* Arithmetic Type Properties::  Determining properties of arithmetic types.
 * Integer Bounds::              Bounds on integer values and representations.
 * Wraparound Arithmetic::       Well-defined behavior on signed overflow.
 * Integer Type Overflow::       General integer overflow checking.
 * Integer Range Overflow::      Integer overflow checking if bounds are known.
 @end menu
 
address@hidden Integer Type Determination
address@hidden Integer Type Determination
address@hidden Arithmetic Type Properties
address@hidden Arithmetic Type Properties
 
 @findex TYPE_IS_INTEGER
address@hidden (@var{t})} is a constant
address@hidden (@var{t})} is an arithmetic constant
 expression that is 1 if the arithmetic type @var{t} is an integer type.
 @code{_Bool} counts as an integer type.
 
 @findex TYPE_SIGNED
address@hidden (@var{t})} is a constant expression
-that is 1 if the arithmetic type @var{t} is a signed integer type or a
address@hidden (@var{t})} is an arithmetic constant expression
+that is 1 if the real type @var{t} is a signed integer type or a
 floating type.  If @var{t} is an integer type, @code{TYPE_SIGNED (@var{t})}
 is an integer constant expression.
 
address@hidden EXPR_SIGNED
address@hidden (@var{e})} is 1 if the real expression @var{e}
+has a signed integer type or a floating type.  If @var{e} is an
+integer constant expression or an arithmetic constant expression,
address@hidden (@var{e})} is likewise.  Although @var{e} is
+evaluated, if @var{e} is free of side effects then @code{EXPR_SIGNED
+(@var{e})} is typically optimized to a constant.
+
 Example usage:
 
 @example
 #include <intprops.h>
 #include <time.h>
+
 enum
 @{
   time_t_is_signed_integer =
     TYPE_IS_INTEGER (time_t) && TYPE_SIGNED (time_t)
 @};
+
+int
+CLOCKS_PER_SEC_is_signed (void)
address@hidden
+  return EXPR_SIGNED (CLOCKS_PER_SEC);
address@hidden
 @end example
 
 @node Integer Bounds
diff --git a/lib/intprops.h b/lib/intprops.h
index 5743eb4..8fff86d 100644
--- a/lib/intprops.h
+++ b/lib/intprops.h
@@ -22,8 +22,7 @@
 
 #include <limits.h>
 
-/* Return an integer value, converted to the same type as the integer
-   expression E after integer type promotion.  V is the unconverted value.  */
+/* Return a value with the common real type of E and V and the value of V.  */
 #define _GL_INT_CONVERT(e, v) (0 * (e) + (v))
 
 /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see
@@ -48,12 +47,12 @@
 /* True if the signed integer expression E uses two's complement.  */
 #define _GL_INT_TWOS_COMPLEMENT(e) (~ _GL_INT_CONVERT (e, 0) == -1)
 
-/* True if the arithmetic type T is signed.  */
+/* True if the real type T is signed.  */
 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
 
-/* Return 1 if the integer expression E, after integer promotion, has
-   a signed type.  */
-#define _GL_INT_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
+/* Return 1 if the real expression E, after promotion, has a
+   signed or floating type.  */
+#define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
 
 
 /* Minimum and maximum values for integer types and expressions.  These
@@ -76,11 +75,11 @@
 /* The maximum and minimum values for the type of the expression E,
    after integer promotion.  E should not have side effects.  */
 #define _GL_INT_MINIMUM(e)                                              \
-  (_GL_INT_SIGNED (e)                                                   \
+  (EXPR_SIGNED (e)                                                      \
    ? - _GL_INT_TWOS_COMPLEMENT (e) - _GL_SIGNED_INT_MAXIMUM (e)         \
    : _GL_INT_CONVERT (e, 0))
 #define _GL_INT_MAXIMUM(e)                                              \
-  (_GL_INT_SIGNED (e)                                                   \
+  (EXPR_SIGNED (e)                                                      \
    ? _GL_SIGNED_INT_MAXIMUM (e)                                         \
    : _GL_INT_NEGATE_CONVERT (e, 1))
 #define _GL_SIGNED_INT_MAXIMUM(e)                                       \
@@ -411,7 +410,7 @@
    : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax))
 #define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \
   ((overflow (a, b) \
-    || (_GL_INT_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \
+    || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \
     || (tmax) < ((a) op (b))) \
    ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 1) \
    : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 0))
-- 
2.1.0