build: move compiler version check to meson

Use the slighly nicer .version_compare() function for GCC; for Clang that is
not possible due to the mess that Apple does with version numbers.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -1128,31 +1128,6 @@ if test "$targetos" = "bogus"; then
     error_exit "Unrecognized host OS (uname -s reports '$(uname -s)')"
 fi
 
-# Check whether the compiler matches our minimum requirements:
-cat > $TMPC << EOF
-#if defined(__clang_major__) && defined(__clang_minor__)
-# ifdef __apple_build_version__
-#  if __clang_major__ < 12 || (__clang_major__ == 12 && __clang_minor__ < 0)
-#   error You need at least XCode Clang v12.0 to compile QEMU
-#  endif
-# else
-#  if __clang_major__ < 10 || (__clang_major__ == 10 && __clang_minor__ < 0)
-#   error You need at least Clang v10.0 to compile QEMU
-#  endif
-# endif
-#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
-# if __GNUC__ < 7 || (__GNUC__ == 7 && __GNUC_MINOR__ < 4)
-#  error You need at least GCC v7.4.0 to compile QEMU
-# endif
-#else
-# error You either need GCC or Clang to compiler QEMU
-#endif
-int main (void) { return 0; }
-EOF
-if ! compile_prog "" "" ; then
-    error_exit "You need at least GCC v7.4 or Clang v10.0 (or XCode Clang v12.0)"
-fi
-
 if test "$static" = "yes" ; then
   if test "$plugins" = "yes"; then
     error_exit "static and plugins are mutually incompatible"

meson.build

@@ -190,6 +190,26 @@ endif
 # Compiler flags #
 ##################
 
+foreach lang : all_languages
+  compiler = meson.get_compiler(lang)
+  if compiler.get_id() == 'gcc' and compiler.version().version_compare('>=7.4')
+    # ok
+  elif compiler.get_id() == 'clang' and compiler.compiles('''
+      #ifdef __apple_build_version__
+      # if __clang_major__ < 12 || (__clang_major__ == 12 && __clang_minor__ < 0)
+      #  error You need at least XCode Clang v12.0 to compile QEMU
+      # endif
+      #else
+      # if __clang_major__ < 10 || (__clang_major__ == 10 && __clang_minor__ < 0)
+      #  error You need at least Clang v10.0 to compile QEMU
+      # endif
+      #endif''')
+    # ok
+  else
+    error('You either need GCC v7.4 or Clang v10.0 (or XCode Clang v12.0) to compile QEMU')
+  endif
+endforeach
+
 # default flags for all hosts
 # We use -fwrapv to tell the compiler that we require a C dialect where
 # left shift of signed integers is well defined and has the expected