Handle intrinsics declared but not used in host subprogram.

When we reach the CONTAINS of a host subprogram, if there are intrinsic
symbols that have been declared by not otherwise used, they must be treated
as normal identifiers. This ensures that internal subprograms are
consistent in how they treat them.

tools/flang1/flang1exe/semant.c

@@ -55,6 +55,7 @@ static void save_host(INTERF *);
 static void restore_host(INTERF *, LOGICAL);
 static void check_end_subprogram(int, int);
 static char *name_of_rutype(int);
+static void convert_intrinsics_to_idents(void);
 static int chk_intrinsic(int, LOGICAL, LOGICAL);
 static int create_func_entry(int);
 static int create_func_entry_result(int);
@@ -1447,6 +1448,7 @@ semant1(int rednum, SST *top)
               CNULL);
         goto executable_shared;
       }
+      convert_intrinsics_to_idents();
       save_host(&host_state);
       gbl.internal = 1;
       restore_host(&host_state, TRUE);
@@ -11988,6 +11990,23 @@ name_of_rutype(int rutype)
   return "";
 }
 
+/* If an intrinsic is declared in a host subprogram and not otherwise used,
+ * convert it to an identifier for the internal subprograms to share.
+ */
+static void
+convert_intrinsics_to_idents()
+{
+  SPTR sptr;
+  assert(gbl.currsub && gbl.internal == 0,
+         "only applicable for non-internal subprogram", 0, ERR_Severe);
+  for (sptr = NOSYM + 1; sptr < stb.firstusym; ++sptr) {
+    if (DCLDG(sptr) && !EXPSTG(sptr) && IS_INTRINSIC(STYPEG(sptr))) {
+      SPTR new_sptr = newsym(sptr);
+      STYPEP(new_sptr, ST_IDENT);
+    }
+  }
+}
+
 /*
  * In certain contexts, a new symbol must be created immediately
  * if the identifier is an intrinsic rather than relying on newsym().