Fix signbit / infinite / isinf / isnan unit tests.

Turns out stlport isn't broken. <cmath> (included
transitively via gtest in our case) is not required
to make C99 math macros (like signbit) available, nor is
it required to preserve them if they're already defined.
It is only required to make the equivalent functions in
namespace std available.

I couldn't find any documentation of required behaviour for
programs that include both <math.h> and <cmath>.

I've verified experimentally that llvm's libc++ and gnu
stl behave the same as stlport.

bug: 12935307

Change-Id: I9dc5cc0fd9f4f259abc8eefb280177cdd092a94b

1 files changed, 50 insertions, 24 deletions

diff --git a/tests/math_test.cpp b/tests/math_test.cpp
index c8974d3b0..fc561bc8c 100644
--- a/tests/math_test.cpp
+++ b/tests/math_test.cpp
@@ -16,11 +16,42 @@
 
 #define _DECLARE_C99_LDBL_MATH 1
 
+// This include (and the associated definition of __test_capture_signbit)
+// must be placed before any files that include <cmath> (gtest.h in this case).
+//
+// <math.h> is required to define generic macros signbit, isfinite and
+// several other such functions.
+//
+// <cmath> is required to undef declarations of these macros in the global
+// namespace and make equivalent functions available in namespace std. Our
+// stlport implementation does this only for signbit, isfinite, isinf and
+// isnan.
+//
+// NOTE: We don't write our test using std::signbit because we want to be
+// sure that we're testing the bionic version of signbit. The C++ libraries
+// are free to reimplement signbit or delegate to compiler builtins if they
+// please.
+#include <math.h>
+
+namespace {
+template<typename T> inline int test_capture_signbit(const T in) {
+  return signbit(in);
+}
+template<typename T> inline int test_capture_isfinite(const T in) {
+  return isfinite(in);
+}
+template<typename T> inline int test_capture_isnan(const T in) {
+  return isnan(in);
+}
+template<typename T> inline int test_capture_isinf(const T in) {
+  return isinf(in);
+}
+}
+
 #include <gtest/gtest.h>
 
 #include <fenv.h>
 #include <limits.h>
-#include <math.h>
 #include <stdint.h>
 
 float float_subnormal() {
@@ -59,27 +90,25 @@ TEST(math, fpclassify) {
   ASSERT_EQ(FP_ZERO, fpclassify(0.0));
 }
 
-/* TODO: stlport breaks the isfinite macro
 TEST(math, isfinite) {
-  ASSERT_TRUE(isfinite(123.0f));
-  ASSERT_TRUE(isfinite(123.0));
-  ASSERT_FALSE(isfinite(HUGE_VALF));
-  ASSERT_FALSE(isfinite(HUGE_VAL));
+  ASSERT_TRUE(test_capture_isfinite(123.0f));
+  ASSERT_TRUE(test_capture_isfinite(123.0));
+  ASSERT_FALSE(test_capture_isfinite(HUGE_VALF));
+  ASSERT_FALSE(test_capture_isfinite(HUGE_VAL));
 }
-*/
 
 TEST(math, isinf) {
-  ASSERT_FALSE(isinf(123.0f));
-  ASSERT_FALSE(isinf(123.0));
-  ASSERT_TRUE(isinf(HUGE_VALF));
-  ASSERT_TRUE(isinf(HUGE_VAL));
+  ASSERT_FALSE(test_capture_isinf(123.0f));
+  ASSERT_FALSE(test_capture_isinf(123.0));
+  ASSERT_TRUE(test_capture_isinf(HUGE_VALF));
+  ASSERT_TRUE(test_capture_isinf(HUGE_VAL));
 }
 
 TEST(math, isnan) {
-  ASSERT_FALSE(isnan(123.0f));
-  ASSERT_FALSE(isnan(123.0));
-  ASSERT_TRUE(isnan(nanf("")));
-  ASSERT_TRUE(isnan(nan("")));
+  ASSERT_FALSE(test_capture_isnan(123.0f));
+  ASSERT_FALSE(test_capture_isnan(123.0));
+  ASSERT_TRUE(test_capture_isnan(nanf("")));
+  ASSERT_TRUE(test_capture_isnan(nan("")));
 }
 
 TEST(math, isnormal) {
@@ -90,19 +119,16 @@ TEST(math, isnormal) {
 }
 
 // TODO: isgreater, isgreaterequals, isless, islessequal, islessgreater, isunordered
-
-/* TODO: stlport breaks the signbit macro
 TEST(math, signbit) {
-  ASSERT_EQ(0, signbit(0.0f));
-  ASSERT_EQ(0, signbit(0.0));
+  ASSERT_EQ(0, test_capture_signbit(0.0f));
+  ASSERT_EQ(0, test_capture_signbit(0.0));
 
-  ASSERT_EQ(0, signbit(1.0f));
-  ASSERT_EQ(0, signbit(1.0));
+  ASSERT_EQ(0, test_capture_signbit(1.0f));
+  ASSERT_EQ(0, test_capture_signbit(1.0));
 
-  ASSERT_NE(0, signbit(-1.0f));
-  ASSERT_NE(0, signbit(-1.0));
+  ASSERT_NE(0, test_capture_signbit(-1.0f));
+  ASSERT_NE(0, test_capture_signbit(-1.0));
 }
-*/
 
 TEST(math, __fpclassifyd) {
 #if defined(__BIONIC__)