Make some header file tests a bit stronger

[Bruno Haible]

When testing a header file, let's check whether all required macros are defined
before including any other header file. This makes the tests somewhat stronger.


2023-03-25  Bruno Haible  <bruno@clisp.org>

        Make some header file tests a bit stronger.
        * tests/test-float.c: Include fpucw.h and macros.h only after checking
        the macros.
        * tests/test-glob-h.c: Include macros.h only after checking the types
        and macros.
        * tests/test-inttypes.c: Don't include <stddef.h>.
        * tests/test-math.c: Include <limits.h> and macros.h only after checking
        the types and macros.
        * tests/test-stddef.c: Include <limits.h> only after checking the types
        and macros.
        * tests/test-sys_select.c: Include signature.h only after checking the
        types.
        * tests/test-sys_socket.c: Include <errno.h> only after checking the
        types and macros.
        * tests/test-wctype-h.c: Include macros.h only after checking the types.

diff --git a/tests/test-float.c b/tests/test-float.c
index 315c3d6610..07c3ad1cf4 100644
--- a/tests/test-float.c
+++ b/tests/test-float.c
@@ -20,12 +20,48 @@
 
 #include <float.h>
 
-#include "fpucw.h"
-#include "macros.h"
-
 /* Check that FLT_RADIX is a constant expression.  */
 int a[] = { FLT_RADIX };
 
+/* ----------------------- Check macros for 'float' ----------------------- */
+
+/* Check that the FLT_* macros expand to constant expressions.  */
+int fb[] =
+  {
+    FLT_MANT_DIG, FLT_MIN_EXP, FLT_MAX_EXP,
+    FLT_DIG, FLT_MIN_10_EXP, FLT_MAX_10_EXP
+  };
+float fc[] = { FLT_EPSILON, FLT_MIN, FLT_MAX };
+
+/* ----------------------- Check macros for 'double' ----------------------- */
+
+/* Check that the DBL_* macros expand to constant expressions.  */
+int db[] =
+  {
+    DBL_MANT_DIG, DBL_MIN_EXP, DBL_MAX_EXP,
+    DBL_DIG, DBL_MIN_10_EXP, DBL_MAX_10_EXP
+  };
+double dc[] = { DBL_EPSILON, DBL_MIN, DBL_MAX };
+
+/* -------------------- Check macros for 'long double' -------------------- */
+
+/* Check that the LDBL_* macros expand to constant expressions.  */
+int lb[] =
+  {
+    LDBL_MANT_DIG, LDBL_MIN_EXP, LDBL_MAX_EXP,
+    LDBL_DIG, LDBL_MIN_10_EXP, LDBL_MAX_10_EXP
+  };
+long double lc1 = LDBL_EPSILON;
+long double lc2 = LDBL_MIN;
+#if 0 /* LDBL_MAX is not a constant expression on some platforms.  */
+long double lc3 = LDBL_MAX;
+#endif
+
+/* ------------------------------------------------------------------------- */
+
+#include "fpucw.h"
+#include "macros.h"
+
 #if FLT_RADIX == 2
 
 /* Return 2^n.  */
@@ -117,14 +153,6 @@ pow2l (int n)
 
 /* ----------------------- Check macros for 'float' ----------------------- */
 
-/* Check that the FLT_* macros expand to constant expressions.  */
-int fb[] =
-  {
-    FLT_MANT_DIG, FLT_MIN_EXP, FLT_MAX_EXP,
-    FLT_DIG, FLT_MIN_10_EXP, FLT_MAX_10_EXP
-  };
-float fc[] = { FLT_EPSILON, FLT_MIN, FLT_MAX };
-
 static void
 test_float (void)
 {
@@ -196,14 +224,6 @@ test_float (void)
 
 /* ----------------------- Check macros for 'double' ----------------------- */
 
-/* Check that the DBL_* macros expand to constant expressions.  */
-int db[] =
-  {
-    DBL_MANT_DIG, DBL_MIN_EXP, DBL_MAX_EXP,
-    DBL_DIG, DBL_MIN_10_EXP, DBL_MAX_10_EXP
-  };
-double dc[] = { DBL_EPSILON, DBL_MIN, DBL_MAX };
-
 static void
 test_double (void)
 {
@@ -275,18 +295,6 @@ test_double (void)
 
 /* -------------------- Check macros for 'long double' -------------------- */
 
-/* Check that the LDBL_* macros expand to constant expressions.  */
-int lb[] =
-  {
-    LDBL_MANT_DIG, LDBL_MIN_EXP, LDBL_MAX_EXP,
-    LDBL_DIG, LDBL_MIN_10_EXP, LDBL_MAX_10_EXP
-  };
-long double lc1 = LDBL_EPSILON;
-long double lc2 = LDBL_MIN;
-#if 0 /* LDBL_MAX is not a constant expression on some platforms.  */
-long double lc3 = LDBL_MAX;
-#endif
-
 static void
 test_long_double (void)
 {
diff --git a/tests/test-glob-h.c b/tests/test-glob-h.c
index 90d542693e..0abd07321e 100644
--- a/tests/test-glob-h.c
+++ b/tests/test-glob-h.c
@@ -20,8 +20,6 @@
 
 #include <glob.h>
 
-#include "macros.h"
-
 /* Check that size_t is defined.  */
 size_t a;
 
@@ -43,6 +41,8 @@ int ret[] =
     GLOB_NOSPACE
   };
 
+#include "macros.h"
+
 int
 main ()
 {
diff --git a/tests/test-inttypes.c b/tests/test-inttypes.c
index 464436a53b..6c27275643 100644
--- a/tests/test-inttypes.c
+++ b/tests/test-inttypes.c
@@ -20,8 +20,6 @@
 
 #include <inttypes.h>
 
-#include <stddef.h>
-
 /* Tests for macros supposed to be defined in inttypes.h.  */
 
 const char *k = /* implicit string concatenation */
diff --git a/tests/test-math.c b/tests/test-math.c
index 874c5969f7..8de6931630 100644
--- a/tests/test-math.c
+++ b/tests/test-math.c
@@ -50,15 +50,15 @@ choke me
 choke me
 #endif
 
-#include <limits.h>
-
-#include "macros.h"
-
 #if 0
 /* Check that NAN expands into a constant expression.  */
 static float n = NAN;
 #endif
 
+#include <limits.h>
+
+#include "macros.h"
+
 /* Compare two numbers with ==.
    This is a separate function because IRIX 6.5 "cc -O" miscompiles an
    'x == x' test.  */
diff --git a/tests/test-stddef.c b/tests/test-stddef.c
index 3ec00a8f25..359fece6c2 100644
--- a/tests/test-stddef.c
+++ b/tests/test-stddef.c
@@ -19,7 +19,6 @@
 #include <config.h>
 
 #include <stddef.h>
-#include <limits.h>
 
 /* Check that appropriate types are defined.  */
 wchar_t a = 'c';
@@ -44,10 +43,6 @@ struct d
 static_assert (sizeof (offsetof (struct d, e)) == sizeof (size_t));
 static_assert (offsetof (struct d, f) == 1);
 
-/* offsetof promotes to an unsigned integer if and only if sizes do
-   not fit in int.  */
-static_assert ((offsetof (struct d, e) < -1) == (INT_MAX < (size_t) -1));
-
 /* Check max_align_t's alignment.  */
 static_assert (alignof (double) <= alignof (max_align_t));
 static_assert (alignof (int) <= alignof (max_align_t));
@@ -92,6 +87,12 @@ test_unreachable_noreturn (void)
   unreachable ();
 }
 
+#include <limits.h> /* INT_MAX */
+
+/* offsetof promotes to an unsigned integer if and only if sizes do
+   not fit in int.  */
+static_assert ((offsetof (struct d, e) < -1) == (INT_MAX < (size_t) -1));
+
 int
 main (void)
 {
diff --git a/tests/test-sys_select.c b/tests/test-sys_select.c
index 701ccc0eed..f8905ce085 100644
--- a/tests/test-sys_select.c
+++ b/tests/test-sys_select.c
@@ -20,6 +20,16 @@
 
 #include <sys/select.h>
 
+/* Check that the 'struct timeval' type is defined.  */
+struct timeval a;
+
+/* Check that a.tv_sec is wide enough to hold a time_t, ignoring
+   signedness issues.  */
+typedef int verify_tv_sec_type[sizeof (time_t) <= sizeof (a.tv_sec) ? 1 : -1];
+
+/* Check that sigset_t is defined.  */
+sigset_t t2;
+
 #include "signature.h"
 
 /* The following may be macros without underlying functions, so only
@@ -37,16 +47,6 @@ SIGNATURE_CHECK (FD_SET, int, (int, fd_set *));
 SIGNATURE_CHECK (FD_ZERO, void, (fd_set *));
 #endif
 
-/* Check that the 'struct timeval' type is defined.  */
-struct timeval a;
-
-/* Check that a.tv_sec is wide enough to hold a time_t, ignoring
-   signedness issues.  */
-typedef int verify_tv_sec_type[sizeof (time_t) <= sizeof (a.tv_sec) ? 1 : -1];
-
-/* Check that sigset_t is defined.  */
-sigset_t t2;
-
 int
 main (void)
 {
diff --git a/tests/test-sys_socket.c b/tests/test-sys_socket.c
index b522c25a17..02ec6373ff 100644
--- a/tests/test-sys_socket.c
+++ b/tests/test-sys_socket.c
@@ -20,8 +20,6 @@
 
 #include <sys/socket.h>
 
-#include <errno.h>
-
 #if HAVE_SHUTDOWN
 /* Check some integer constant expressions.  */
 int a[] = { SHUT_RD, SHUT_WR, SHUT_RDWR };
@@ -40,6 +38,8 @@ struct iovec io;
 /* Check that a minimal set of 'struct msghdr' is defined.  */
 struct msghdr msg;
 
+#include <errno.h>
+
 int
 main (void)
 {
diff --git a/tests/test-wctype-h.c b/tests/test-wctype-h.c
index e413d4bedd..ceee02bc7f 100644
--- a/tests/test-wctype-h.c
+++ b/tests/test-wctype-h.c
@@ -20,8 +20,6 @@
 
 #include <wctype.h>
 
-#include "macros.h"
-
 /* Check that the type wint_t is defined.  */
 wint_t a = 'x';
 /* Check that WEOF is defined.  */
@@ -33,6 +31,8 @@ wctype_t p;
 /* Check that the type wctrans_t is defined.  */
 wctrans_t q;
 
+#include "macros.h"
+
 int
 main (void)
 {