Details

- new error message for "attempt to assign to const variable"
- note in the manual about compatibility options
- comments
- small changes in 'read_line' and 'pushstr'

liolib.c

@@ -504,17 +504,17 @@ static int test_eof (lua_State *L, FILE *f) {
 
 static int read_line (lua_State *L, FILE *f, int chop) {
   luaL_Buffer b;
-  int c = '\0';
+  int c;
   luaL_buffinit(L, &b);
-  while (c != EOF && c != '\n') {  /* repeat until end of line */
+  do {  /* may need to read several chunks to get whole line */
-    char *buff = luaL_prepbuffer(&b);  /* preallocate buffer */
+    char *buff = luaL_prepbuffer(&b);  /* preallocate buffer space */
     int i = 0;
     l_lockfile(f);  /* no memory errors can happen inside the lock */
     while (i < LUAL_BUFFERSIZE && (c = l_getc(f)) != EOF && c != '\n')
-      buff[i++] = c;
+      buff[i++] = c;  /* read up to end of line or buffer limit */
     l_unlockfile(f);
     luaL_addsize(&b, i);
-  }
+  } while (c != EOF && c != '\n');  /* repeat until end of line */
   if (!chop && c == '\n')  /* want a newline and have one? */
     luaL_addchar(&b, c);  /* add ending newline to result */
   luaL_pushresult(&b);  /* close buffer */

lobject.c

@@ -419,9 +419,9 @@ typedef struct BuffFS {
 static void pushstr (BuffFS *buff, const char *str, size_t l) {
   lua_State *L = buff->L;
   setsvalue2s(L, L->top, luaS_newlstr(L, str, l));
-  L->top++;
+  L->top++;  /* may use one extra slot */
   buff->pushed++;
-  if (buff->pushed > 1 && L->top + 2 > L->stack_last) {
+  if (buff->pushed > 1 && L->top + 1 >= L->stack_last) {
     luaV_concat(L, buff->pushed);  /* join all partial results into one */
     buff->pushed = 1;
   }

lparser.c

@@ -264,7 +264,7 @@ static void check_readonly (LexState *ls, expdesc *e) {
   Vardesc *vardesc = getvardesc(ls->fs, e);
   if (vardesc && vardesc->ro) {  /* is variable local and const? */
     const char *msg = luaO_pushfstring(ls->L,
-       "assignment to const variable '%s'", getstr(vardesc->name));
+       "attempt to assign to const variable '%s'", getstr(vardesc->name));
     luaK_semerror(ls, msg);  /* error */
   }
 }

lstate.h

@@ -26,6 +26,22 @@
 ** 'fixedgc': all objects that are not to be collected (currently
 ** only small strings, such as reserved words).
 **
+** For the generational collector, some of these lists have marks for
+** generations. Each mark points to the first element in the list for
+** that particular generation; that generation goes until the next mark.
+**
+** 'allgc' -> 'survival': new objects;
+** 'survival' -> 'old': objects that survived one collection;
+** 'old' -> 'reallyold': objects that became old in last collection;
+** 'reallyold' -> NULL: objects old for more than one cycle.
+**
+** 'finobj' -> 'finobjsur': new objects marked for finalization;
+** 'finobjsur' -> 'finobjold': survived   """";
+** 'finobjold' -> 'finobjrold': just old  """";
+** 'finobjrold' -> NULL: really old       """".
+*/
+
+/*
 ** Moreover, there is another set of lists that control gray objects.
 ** These lists are linked by fields 'gclist'. (All objects that
 ** can become gray have such a field. The field is not the same

luaconf.h

@@ -344,8 +344,8 @@
 /*
 @@ LUA_COMPAT_MATHLIB controls the presence of several deprecated
 ** functions in the mathematical library.
-** (These functions were already officially removed in 5.3, but
+** (These functions were already officially removed in 5.3;
-** nevertheless they are available by default there.)
+** nevertheless they are still available here.)
 */
 #define LUA_COMPAT_MATHLIB
 
@@ -353,23 +353,25 @@
 @@ LUA_COMPAT_APIINTCASTS controls the presence of macros for
 ** manipulating other integer types (lua_pushunsigned, lua_tounsigned,
 ** luaL_checkint, luaL_checklong, etc.)
+** (These macros were also officially removed in 5.3, but they are still
+** available here.)
 */
 #define LUA_COMPAT_APIINTCASTS
 
+
 /*
 @@ LUA_COMPAT_LT_LE controls the emulation of the '__le' metamethod
 ** using '__lt'.
 */
 #define LUA_COMPAT_LT_LE
 
-#endif				/* } */
-
-
 
 /*
 @@ The following macros supply trivial compatibility for some
 ** changes in the API. The macros themselves document how to
 ** change your code to avoid using them.
+** (Once more, these macros were officially removed in 5.3, but they are
+** still available here.)
 */
 #define lua_strlen(L,i)		lua_rawlen(L, (i))
 
@@ -378,6 +380,8 @@
 #define lua_equal(L,idx1,idx2)		lua_compare(L,(idx1),(idx2),LUA_OPEQ)
 #define lua_lessthan(L,idx1,idx2)	lua_compare(L,(idx1),(idx2),LUA_OPLT)
 
+#endif				/* } */
+
 /* }================================================================== */
 
 

manual/manual.of

@@ -8774,10 +8774,18 @@ is a more portable solution.
 
 Here we list the incompatibilities that you may find when moving a program
 from @N{Lua 5.3} to @N{Lua 5.4}.
+
 You can avoid some incompatibilities by compiling Lua with
 appropriate options (see file @id{luaconf.h}).
 However,
 all these compatibility options will be removed in the future.
+More often than not,
+compatibility issues arise when these compatibility options
+are removed.
+So, whenever you have the chance,
+you should try to test your code with a version of Lua compiled
+with all compatibility options turned off.
+That will ease transitions to newer versions of Lua.
 
 Lua versions can always change the C API in ways that
 do not imply source-code changes in a program,
@@ -8825,11 +8833,6 @@ over integers changed in some details.
 In particular, the control variable never wraps around.
 }
 
-@item{
-When a coroutine finishes with an error,
-its stack is unwound (to run any pending closing methods).
-}
-
 @item{
 A label for a @Rw{goto} cannot be declared where a label with the same
 name is visible, even if this other label is declared in an enclosing

testes/constructs.lua

@@ -215,7 +215,7 @@ do   -- testing constants
   checkload(prog, "unknown attribute 'XXX'")
 
   checkload([[local <const> xxx = 20; xxx = 10]],
-             ":1: assignment to const variable 'xxx'")
+             ":1: attempt to assign to const variable 'xxx'")
 
   checkload([[
     local xx;
@@ -225,12 +225,12 @@ do   -- testing constants
       local abc = xx + yyy + xxx;
       return function () return function () xxx = yyy end end
     end
-  ]], ":6: assignment to const variable 'xxx'")
+  ]], ":6: attempt to assign to const variable 'xxx'")
 
   checkload([[
     local <toclose> x = nil
     x = io.open()
-  ]], ":2: assignment to const variable 'x'")
+  ]], ":2: attempt to assign to const variable 'x'")
 end
 
 f = [[

testes/locals.lua

@@ -452,7 +452,6 @@ do
   end)
   assert(co() == 100)
   local st, msg = pcall(co)
-print(msg)
   -- should get last error raised
   assert(not st and string.find(msg, "%w+%.%w+:%d+: XXX"))
 end

testes/strings.lua

@@ -3,7 +3,8 @@
 
 print('testing strings and string library')
 
-local maxi, mini = math.maxinteger, math.mininteger
+local <const> maxi = math.maxinteger
+local <const> mini = math.mininteger
 
 
 local function checkerror (msg, f, ...)