Cleanup: remove workarounds and version checks for unsupported compilers

Match minimum supported versions from the WIKI [0] by raising them to:

- GCC 9.3.1
- CLANG 8.0
- MVCS 2019 (16.9.16 / 1928)

Details:

- Add CMake checks that ensure supported compiler versions early on.
- Previously GCC per-processor version checks served to exclude
  `__clang__`, in some cases this has been replaced by explicitly
  excluding `__clang__`. This was needed as CLANG treated some of these
  flags differently to GCC, causing the build to fail.
- Remove USE_APPLE_OMP_FIX GCC-4.2 OpenMP workaround.
- Remove linking error workaround for old MSVC versions.

[0]: https://wiki.blender.org/wiki/Building_Blender

Reviewed by: brecht, LazyDodo

Ref D16068

7 files changed, 12 insertions, 47 deletions

diff --git a/source/blender/blenlib/BLI_assert.h b/source/blender/blenlib/BLI_assert.h
index 4a7fae6e98c..4292620e462 100644
--- a/source/blender/blenlib/BLI_assert.h
+++ b/source/blender/blenlib/BLI_assert.h
@@ -67,7 +67,7 @@ void _BLI_assert_unreachable_print(const char *file, int line, const char *funct
 #  define BLI_STATIC_ASSERT(a, msg) static_assert(a, msg);
 #elif defined(_MSC_VER)
 /* Visual Studio */
-#  if (_MSC_VER > 1910) && !defined(__clang__)
+#  if !defined(__clang__)
 #    define BLI_STATIC_ASSERT(a, msg) static_assert(a, msg);
 #  else
 #    define BLI_STATIC_ASSERT(a, msg) _STATIC_ASSERT(a);
diff --git a/source/blender/blenlib/BLI_compiler_attrs.h b/source/blender/blenlib/BLI_compiler_attrs.h
index 99f0aa9f049..9ee626296cb 100644
--- a/source/blender/blenlib/BLI_compiler_attrs.h
+++ b/source/blender/blenlib/BLI_compiler_attrs.h
@@ -25,7 +25,7 @@
 #endif
 
 /* never returns NULL */
-#if (__GNUC__ * 100 + __GNUC_MINOR__) >= 409 /* gcc4.9+ only */
+#ifdef __GNUC__
 #  define ATTR_RETURNS_NONNULL __attribute__((returns_nonnull))
 #else
 #  define ATTR_RETURNS_NONNULL
@@ -39,14 +39,14 @@
 #endif
 
 /* hint to treat any non-null function return value cannot alias any other pointer */
-#if (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 403))
+#ifdef __GNUC__
 #  define ATTR_MALLOC __attribute__((malloc))
 #else
 #  define ATTR_MALLOC
 #endif
 
 /* the function return value points to memory (2 args for 'size * tot') */
-#if (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 403))
+#ifdef __GNUC__
 #  define ATTR_ALLOC_SIZE(args...) __attribute__((alloc_size(args)))
 #else
 #  define ATTR_ALLOC_SIZE(...)
@@ -69,7 +69,7 @@
 
 /* Use to suppress '-Wimplicit-fallthrough' (in place of 'break'). */
 #ifndef ATTR_FALLTHROUGH
-#  if defined(__GNUC__) && (__GNUC__ >= 7) /* gcc7.0+ only */
+#  ifdef __GNUC__
 #    define ATTR_FALLTHROUGH __attribute__((fallthrough))
 #  else
 #    define ATTR_FALLTHROUGH ((void)0)
diff --git a/source/blender/blenlib/BLI_endian_switch_inline.h b/source/blender/blenlib/BLI_endian_switch_inline.h
index ce44348d4dd..32cb0f234f2 100644
--- a/source/blender/blenlib/BLI_endian_switch_inline.h
+++ b/source/blender/blenlib/BLI_endian_switch_inline.h
@@ -26,7 +26,7 @@ BLI_INLINE void BLI_endian_switch_int16(short *val)
 }
 BLI_INLINE void BLI_endian_switch_uint16(unsigned short *val)
 {
-#if (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 408)) /* gcc4.8+ only */
+#ifdef __GNUC__
   *val = __builtin_bswap16(*val);
 #else
   unsigned short tval = *val;
diff --git a/source/blender/blenlib/BLI_math_inline.h b/source/blender/blenlib/BLI_math_inline.h
index bf91c9108a9..b190b022a88 100644
--- a/source/blender/blenlib/BLI_math_inline.h
+++ b/source/blender/blenlib/BLI_math_inline.h
@@ -28,8 +28,8 @@ extern "C" {
 #  define MALWAYS_INLINE
 #endif
 
-/* gcc 4.6 (supports push/pop) */
-#if (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 406))
+/* Check for GCC push/pop pragma support. */
+#ifdef __GNUC__
 #  define BLI_MATH_GCC_WARN_PRAGMA 1
 #endif
 
diff --git a/source/blender/blenlib/BLI_strict_flags.h b/source/blender/blenlib/BLI_strict_flags.h
index 8489871d5da..cc5b5dce363 100644
--- a/source/blender/blenlib/BLI_strict_flags.h
+++ b/source/blender/blenlib/BLI_strict_flags.h
@@ -9,16 +9,12 @@
  */
 
 #ifdef __GNUC__
-#  if (__GNUC__ * 100 + __GNUC_MINOR__) >= 406 /* gcc4.6+ only */
+/* NOTE(@campbellbarton): CLANG behaves slightly differently to GCC,
+ * these can be enabled but do so carefully as they can introduce build-errors.  */
+#  if !defined(__clang__)
 #    pragma GCC diagnostic error "-Wsign-compare"
-#  endif
-#  if __GNUC__ >= 6 /* gcc6+ only */
 #    pragma GCC diagnostic error "-Wconversion"
-#  endif
-#  if (__GNUC__ * 100 + __GNUC_MINOR__) >= 408
-/* gcc4.8+ only (behavior changed to ignore globals). */
 #    pragma GCC diagnostic error "-Wshadow"
-/* older gcc changed behavior with ternary */
 #    pragma GCC diagnostic error "-Wsign-conversion"
 #  endif
 /* pedantic gives too many issues, developers can define this for own use */
diff --git a/source/blender/blenlib/BLI_winstuff.h b/source/blender/blenlib/BLI_winstuff.h
index 7201e1bb4a1..34f1b1a68f1 100644
--- a/source/blender/blenlib/BLI_winstuff.h
+++ b/source/blender/blenlib/BLI_winstuff.h
@@ -48,11 +48,6 @@ extern "C" {
 #  define S_ISDIR(x) (((x)&_S_IFDIR) == _S_IFDIR)
 #endif
 
-/* Defines for using ISO C++ conferment names. */
-#if !defined(_MSC_VER) || _MSC_VER < 1900
-#  define snprintf _snprintf
-#endif
-
 #if defined(_MSC_VER)
 #  define R_OK 4
 #  define W_OK 2
diff --git a/source/blender/blenlib/intern/threads.cc b/source/blender/blenlib/intern/threads.cc
index 156f2a7b338..f99a27c2475 100644
--- a/source/blender/blenlib/intern/threads.cc
+++ b/source/blender/blenlib/intern/threads.cc
@@ -37,17 +37,6 @@
 
 #include "atomic_ops.h"
 
-#if defined(__APPLE__) && defined(_OPENMP) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 2) && \
-    !defined(__clang__)
-#  define USE_APPLE_OMP_FIX
-#endif
-
-#ifdef USE_APPLE_OMP_FIX
-/* ************** libgomp (Apple gcc 4.2.1) TLS bug workaround *************** */
-extern pthread_key_t gomp_tls_key;
-static void *thread_tls_data;
-#endif
-
 /**
  * Basic Thread Control API
  * ========================
@@ -153,15 +142,7 @@ void BLI_threadpool_init(ListBase *threadbase, void *(*do_thread)(void *), int t
     }
   }
 
-  uint level = atomic_fetch_and_add_u(&thread_levels, 1);
-  if (level == 0) {
-#ifdef USE_APPLE_OMP_FIX
-    /* Workaround for Apple gcc 4.2.1 OMP vs background thread bug,
-     * we copy GOMP thread local storage pointer to setting it again
-     * inside the thread that we start. */
-    thread_tls_data = pthread_getspecific(gomp_tls_key);
-#endif
-  }
+  atomic_fetch_and_add_u(&thread_levels, 1);
 }
 
 int BLI_available_threads(ListBase *threadbase)
@@ -194,13 +175,6 @@ int BLI_threadpool_available_thread_index(ListBase *threadbase)
 static void *tslot_thread_start(void *tslot_p)
 {
   ThreadSlot *tslot = (ThreadSlot *)tslot_p;
-
-#ifdef USE_APPLE_OMP_FIX
-  /* Workaround for Apple gcc 4.2.1 OMP vs background thread bug,
-   * set GOMP thread local storage pointer which was copied beforehand */
-  pthread_setspecific(gomp_tls_key, thread_tls_data);
-#endif
-
   return tslot->do_thread(tslot->callerdata);
 }