Fix termination when saving long-named expressions in a pre-proc loop

It was not intended in #500 that this warning crashes form, which happened
here when Save was called in a pre-processor loop. This is due to the
leading & of the message which triggers the source file line information.
Warning protects from the crash by temporarily setting the "iswarning"
variable which causes MesPrint to then not terminate.

This can be easily cleaned up later if Warning is refactored to take a
format string and variable arguments.

check/fixes.frm

@@ -1910,6 +1910,18 @@ Save test.res abcdefghijklmnop;
 .end
 assert succeeded?
 *--#] Issue192_3 :
+*--#[ Issue192_4 :
+* Also related: Issue 334.
+Global abcdefghijklmnop1 = 17;
+Global abcdefghijklmnop2 = 17;
+.store
+#do i = 1,2
+    Save test.res abcdefghijklmnop`i';
+#enddo
+.end
+assert warning?("saved expr name over 16 char: abcdefghijklmnop1")
+assert warning?("saved expr name over 16 char: abcdefghijklmnop2")
+*--#] Issue192_4 :
 *--#[ Issue197 :
 * mul_ ignores denominator factors
 #if "{2^32}" == "0"

sources/store.c

@@ -423,7 +423,9 @@ int CoSave(UBYTE *inp)
 			if ( GetVar(inp,&type,&number,CEXPRESSION,NOAUTO) != NAMENOTFOUND ) {
 				if ( e[number].status == STOREDEXPRESSION ) {
 					if ( StrLen(AC.exprnames->namebuffer+e[number].name) > MAXENAME ) {
-						MesPrint("&Warning: saved expr name over %d char: %s", MAXENAME, AC.exprnames->namebuffer+e[number].name);
+						char msg[100];
+						snprintf(msg, sizeof(msg), "saved expr name over %d char: %s", MAXENAME, AC.exprnames->namebuffer+e[number].name);
+						Warning(msg);
 					}
 /*
 		Here we have to locate the stored expression, copy its index entry
@@ -525,7 +527,9 @@ NextExpr:;
 		/* Make sure there is at least one stored expression: */
 		if ( n > 0 ) { do {
 			if ( StrLen(AC.exprnames->namebuffer+e->name) > MAXENAME ) {
-				MesPrint("&Warning: saved expr name over %d char: %s", MAXENAME, AC.exprnames->namebuffer+e->name);
+				char msg[100];
+				snprintf(msg, sizeof(msg), "saved expr name over %d char: %s", MAXENAME, AC.exprnames->namebuffer+e->name);
+				Warning(msg);
 			}
 			if ( e->status == STOREDEXPRESSION ) exprInStorageFlag = 1;
 			e++;