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A to-be-closed variable must have a closable value (or be nil)

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It is an error for a to-be-closed variable to have a non-closable
non-nil value when it is being closed. This situation does not seem to
be useful and often hints to an error. (Particularly in the C API, it is
easy to change a to-be-closed index by mistake.)
This commit is contained in:
Roberto Ierusalimschy
2018-11-29 16:02:44 -02:00
parent 7696c6474f
commit 6d04537ea6
9 changed files with 83 additions and 39 deletions
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manual/manual.of
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@@ -1063,11 +1063,16 @@ which start with @T{0x} or @T{0X}.
Hexadecimal constants also accept an optional fractional part
plus an optional binary exponent,
marked by a letter @Char{p} or @Char{P}.
A numeric constant with a radix point or an exponent
denotes a float;
otherwise,
if its value fits in an integer,
it denotes an integer.
if its value fits in an integer or it is a hexadecimal constant,
it denotes an integer;
otherwise (that is, a decimal integer numeral that overflows),
it denotes a float.
(Hexadecimal integer numerals that overflow @emph{wrap around};
they always denote an integer value.)
Examples of valid integer constants are
@verbatim{
3 345 0xff 0xBEBADA
@@ -1542,7 +1547,8 @@ If the value of the variable when it goes out of scope is a function,
that function is called;
otherwise, if the value has a @idx{__close} metamethod,
that metamethod is called;
otherwise, nothing is done.
otherwise, if the value is @nil, nothing is done;
otherwise, an error is raised.
In the function case,
if the scope is being closed by an error,
the error object is passed as an argument to the function;
@@ -1665,7 +1671,7 @@ If both operands are integers,
the operation is performed over integers and the result is an integer.
Otherwise, if both operands are numbers,
then they are converted to floats,
the operation is performed following the usual rules
the operation is performed following the machine's rules
for floating-point arithmetic
(usually the @x{IEEE 754} standard),
and the result is a float.
@@ -4998,7 +5004,7 @@ This call leaves the final string on the top of the stack.
}
If you know beforehand the total size of the resulting string,
If you know beforehand the maximum size of the resulting string,
you can use the buffer like this:
@itemize{
@@ -5012,7 +5018,8 @@ size @id{sz} with a call @T{luaL_buffinitsize(L, &b, sz)}.}
@item{
Finish by calling @T{luaL_pushresultsize(&b, sz)},
where @id{sz} is the total size of the resulting string
copied into that space.
copied into that space (which may be smaller than or
equal to the preallocated size).
}
}
@@ -5028,8 +5035,8 @@ when you call a buffer operation,
the stack is at the same level
it was immediately after the previous buffer operation.
(The only exception to this rule is @Lid{luaL_addvalue}.)
After calling @Lid{luaL_pushresult} the stack is back to its
level when the buffer was initialized,
After calling @Lid{luaL_pushresult},
the stack is back to its level when the buffer was initialized,
plus the final string on its top.
}
@@ -7118,7 +7125,7 @@ empty string as a match immediately after another match.
As an example,
consider the results of the following code:
@verbatim{
> string.gsub("abc", "()a*()", print)
> string.gsub("abc", "()a*()", print);
--> 1 2
--> 3 3
--> 4 4