[gtk/324.c89] gtk/fallback-c89.c: Add fallback for fmin()

[Chun-wei Fan <fanchunwei src gnome org>]

commit 91343251b98f752e1b4e6cef1e4305e085cbc289
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed Dec 23 11:28:10 2020 +0800

    gtk/fallback-c89.c: Add fallback for fmin()
    
    fmin() is a function that is introduced with C99/C++11, so check for the
    presence of it and provide a simple implementation for it if it does not
    exist.
    
    Also update the config.h.win32.in template accordingly, since this
    function is provided on Visual Studio 2013 or later.

 config.h.meson          | 3 +++
 config.h.win32.in       | 5 +++++
 configure.ac            | 2 +-
 gtk/fallback-c89.c      | 8 ++++++++
 gtk/gtkscrolledwindow.c | 2 +-
 meson.build             | 1 +
 6 files changed, 19 insertions(+), 2 deletions(-)
---
diff --git a/config.h.meson b/config.h.meson
index 2af55473fc..eb347ae538 100644
--- a/config.h.meson
+++ b/config.h.meson
@@ -44,6 +44,9 @@
 /* Define to 1 if you have the `flockfile' function. */
 #mesondefine HAVE_FLOCKFILE
 
+/* Define to 1 if you have the `fmin' function. */
+#mesondefine HAVE_FMIN
+
 /* Define to 1 if you have the <ftw.h> header file. */
 #mesondefine HAVE_FTW_H
 
diff --git a/config.h.win32.in b/config.h.win32.in
index 62fe46149c..d0546db297 100644
--- a/config.h.win32.in
+++ b/config.h.win32.in
@@ -52,6 +52,11 @@
 /* Define to 1 if you have the `flockfile' function. */
 #undef HAVE_FLOCKFILE
 
+/* Define to 1 if you have the `fmin' function. */
+#if !defined (_MSC_VER) || (_MSC_VER >= 1800)
+# define HAVE_FMIN 1
+#endif
+
 /* Define to 1 if you have the <ftw.h> header file. */
 /* #undef HAVE_FTW_H */
 
diff --git a/configure.ac b/configure.ac
index 51467bb6cc..acafa2f603 100644
--- a/configure.ac
+++ b/configure.ac
@@ -843,7 +843,7 @@ AC_TYPE_UID_T
 # Check for round(), rint(), isnan() and isinf()
 # Check for log2(), exp2(), nearbyint() and trunc()
 AC_CHECK_LIB(m,round,,)
-AC_CHECK_FUNCS(round rint nearbyint sincos exp2 log2 trunc)
+AC_CHECK_FUNCS(round rint nearbyint sincos exp2 log2 trunc fmin)
 AC_CHECK_DECLS([isnan, isinf], [], [], [[#include <math.h>]])
 
 AC_MSG_CHECKING(whether to build dynamic modules)
diff --git a/gtk/fallback-c89.c b/gtk/fallback-c89.c
index 737983c049..1bfa3fb3b3 100644
--- a/gtk/fallback-c89.c
+++ b/gtk/fallback-c89.c
@@ -126,3 +126,11 @@ isnan (double x)
   return _isnan (x);
 }
 #endif
+
+#ifndef HAVE_FMIN
+static inline double
+fmin (double x, double y)
+{
+  return x < y ? x : y;
+}
+#endif
diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index 408c09265d..bea7339f39 100644
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -48,7 +48,7 @@
 #include "gtkprogresstrackerprivate.h"
 #include "gtksettingsprivate.h"
 
-#include <math.h>
+#include "fallback-c89.c"
 
 /**
  * SECTION:gtkscrolledwindow
diff --git a/meson.build b/meson.build
index b2eaa33a88..405c5a511c 100644
--- a/meson.build
+++ b/meson.build
@@ -252,6 +252,7 @@ check_functions = [
   'sincos',
   'trunc',
   'localtime_r',
+  'fmin',
 ]
 
 foreach func : check_functions