c++: Function declared with typedef with eh-specification.

We just need to handle the exception specification like other properties of
a function typedef.

	PR c++/90731
	* decl.c (grokdeclarator): Propagate eh spec from typedef.

gcc/cp/ChangeLog

+2020-01-28  Jason Merrill  <jason@redhat.com>
+
+	PR c++/90731
+	* decl.c (grokdeclarator): Propagate eh spec from typedef.
+
 2020-01-28  Martin Liska  <mliska@suse.cz>
 
 	PR c++/92440

gcc/cp/decl.c

@@ -12848,6 +12848,7 @@ grokdeclarator (const cp_declarator *declarator,
 	  memfn_quals |= type_memfn_quals (type);
 	  rqual = type_memfn_rqual (type);
 	  type_quals = TYPE_UNQUALIFIED;
+	  raises = TYPE_RAISES_EXCEPTIONS (type);
 	}
     }
 

gcc/testsuite/g++.dg/cpp1z/noexcept-type22.C

+// PR c++/90731
+// { dg-do compile { target c++17 } }
+
+typedef void T() noexcept(true);
+T t;
+void t() noexcept(true);