Introduce $(intcmp ...) for numerical comparison

Numbers can come from $(words ...), automatic variables such as
$(MAKELEVEL), from environment variables, or from shell output such as
through $(shell expr ...).  The $(intcmp ...) function allows
conditional evaluation controlled by numerical variables.

* NEWS: Announce this feature.
* doc/make.texi (Functions for Conditionals): Document 'intcmp'.
* src/function.c (func_intcmp): Create the 'intcmp' built-in function.
* tests/scripts/functions/intcmp: Test the 'intcmp' built-in function.

1 files changed, 37 insertions, 1 deletions

diff --git a/doc/make.texi b/doc/make.texi
index f97f15ff..3dea24f1 100644
--- a/doc/make.texi
+++ b/doc/make.texi
@@ -7820,7 +7820,7 @@ the file names to refer to an existing file or directory.  Use the
 @section Functions for Conditionals
 @findex if
 @cindex conditional expansion
-There are three functions that provide conditional expansion.  A key
+There are four functions that provide conditional expansion.  A key
 aspect of these functions is that not all of the arguments are
 expanded initially.  Only those arguments which need to be expanded,
 will be expanded.
@@ -7867,6 +7867,35 @@ empty string the processing stops and the result of the expansion is
 the empty string.  If all arguments expand to a non-empty string then
 the result of the expansion is the expansion of the last argument.
 
+@item $(intcmp @var{lhs},@var{rhs}[,@var{lt-part}[,@var{eq-part}[,@var{gt-part}]]])
+@findex intcmp
+The @code{intcmp} function provides support for numerical comparison of
+integers.  This function has no counterpart among the GNU @code{make} makefile
+conditionals.
+
+The left-hand side, @var{lhs}, and right-hand side, @var{rhs}, are expanded
+and parsed as integral numbers in base 10.  Expansion of the remaining
+arguments is controlled by how the numerical left-hand side compares to the
+numerical right-hand side.
+
+If there are no further arguments, then the function expands to empty if the
+left-hand side and right-hand side do not compare equal, or to their numerical
+value if they do compare equal.
+
+Else if the left-hand side is strictly less than the right-hand side, the
+@code{intcmp} function evaluates to the expansion of the third argument,
+@var{lt-part}.  If both sides compare equal, then the @code{intcmp} function
+evaluates to the expansion of the fourth argument, @var{eq-part}.  If the
+left-hand side is strictly greater than the right-hand side, then the
+@code{intcmp} function evaluates to the expansion of the fifth argument,
+@var{gt-part}.
+
+If @var{gt-part} is missing, it defaults to @var{eq-part}.  If @var{eq-part}
+is missing, it defaults to the empty string.  Thus both @samp{$(intcmp
+9,7,hello)} and @samp{$(intcmp 9,7,hello,world,)} evaluate to the empty
+string, while @samp{$(intcmp 9,7,hello,world)} (notice the absence of a comma
+after @code{world}) evaluates to @samp{world}.
+
 @end table
 
 @node Let Function, Foreach Function, Conditional Functions, Functions
@@ -12707,6 +12736,13 @@ all expansions result in a non-empty string, substitute the expansion
 of the last @var{condition}.@*
 @xref{Conditional Functions, ,Functions for Conditionals}.
 
+@item $(intcmp @var{lhs},@var{rhs}[,@var{lt-part}[,@var{eq-part}[,@var{gt-part}]]])
+Compare @var{lhs} and @var{rhs} numerically; substitute the expansion of
+@var{lt-part}, @var{eq-part}, or @var{gt-part} depending on whether the
+left-hand side is less-than, equal-to, or greater-than the right-hand
+side, respectively.@*
+@xref{Conditional Functions, ,Functions for Conditionals}.
+
 @item $(call @var{var},@var{param},@dots{})
 Evaluate the variable @var{var} replacing any references to @code{$(1)},
 @code{$(2)} with the first, second, etc.@: @var{param} values.@*