IWYU support (part 3): Improve Visual Studio compatibility

src/explosion.cpp

@@ -12,6 +12,7 @@
 #include "game.h"
 #include "item_factory.h"
 #include "json.h"
+#include "math_defines.h"
 #include "map.h"
 #include "messages.h"
 #include "output.h"
@@ -23,9 +24,6 @@
 #include "vehicle.h"
 #include "vpart_position.h"
 
-// For M_PI
-#define _USE_MATH_DEFINES
-#include <cmath>
 #include <queue>
 #include <random>
 

src/math_defines.h

@@ -0,0 +1,17 @@
+#ifndef CATA_MATH_DEFINES_H
+#define CATA_MATH_DEFINES_H
+
+// On Visual Studio math.h only provides the defines (M_PI, etc.) if
+// _USE_MATH_DEFINES is defined before including it.
+// We centralize that requirement in this header so that IWYU can force this
+// header to be included when such defines are used, via mappings.
+// At time of writing only M_PI has a mapping, which is the most commonly used
+// one.  If more are needed, add them to tools/iwyu/vs.stdlib.imp.
+
+// Note that it's important to use math.h here, not cmath.  See
+// https://stackoverflow.com/questions/6563810/m-pi-works-with-math-h-but-not-with-cmath-in-visual-studio/6563891
+
+#define _USE_MATH_DEFINES
+#include <math.h>
+
+#endif // CATA_MATH_DEFINES_H

src/posix_time.h

@@ -2,16 +2,18 @@
 #ifndef TIME_SPEC_H
 #define TIME_SPEC_H
 
+// Compatibility header.  On POSIX, just include <ctime>.  On Windows, provide
+// our own nanosleep implementation.
+
+#include <ctime> // IWYU pragma: keep
+
 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
 /* Windows platforms.  */
 
 /* Windows lacks the nanosleep() function. The following code was stuffed
    together from GNUlib (http://www.gnu.org/software/gnulib/), which is
    licensed under the GPLv3. */
 
-#include <cerrno>
-#include <ctime>
-
 enum { BILLION = 1000 * 1000 * 1000 };
 
 #   ifdef __cplusplus

src/rng.cpp

@@ -1,14 +1,12 @@
 #include "rng.h"
 
 #include <chrono>
-
-#include "output.h"
-
-#define _USE_MATH_DEFINES
 #include <cmath>
 #include <cstdlib>
 #include <random>
 
+#include "output.h"
+
 long rng( long val1, long val2 )
 {
     long minVal = ( val1 < val2 ) ? val1 : val2;

src/sdltiles.cpp

@@ -54,6 +54,8 @@
 #   ifndef strcasecmp
 #       define strcasecmp StrCmpI
 #   endif
+#else
+#   include <strings.h> // for strcasecmp
 #endif
 
 #ifdef __ANDROID__

tools/iwyu/cata.imp

@@ -1,4 +1,5 @@
 [
     { ref: "gcc.stdlib.imp" },
+    { ref: "vs.stdlib.imp" },
     { ref: "sdl.imp" },
 ]

tools/iwyu/gcc.stdlib.imp

@@ -11,6 +11,7 @@
     { include: ["<ext/new_allocator.h>", "private", "<unordered_set>", "public"] },
     { include: ["<debug/array>", "private", "<array>", "public"] },
     { include: ["<debug/bitset>", "private", "<bitset>", "public"] },
+    { include: ["<debug/deque>", "private", "<deque>", "public"] },
     { include: ["<debug/vector>", "private", "<vector>", "public"] },
     { include: ["<debug/list>", "private", "<list>", "public"] },
     { include: ["<debug/map.h>", "private", "<map>", "public"] },

tools/iwyu/vs.stdlib.imp

@@ -0,0 +1,5 @@
+[
+    { symbol: ["M_PI", "private", "\"math_defines.h\"", "public"] },
+    { symbol: ["nanosleep", "private", "\"posix_time.h\"", "public"] },
+    { symbol: ["timespec", "private", "\"posix_time.h\"", "public"] },
+]