Hi,
On Tuesday, 23 April, 2024 at 03:41:35 pm IST, Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>EOL is a statement separator.
* Right. So are semi-colon (;), braces (}{) and colon (:) in case of C and Python.
===
$ cat t.c
#include <stdio.h>
int main (void)
{ printf("Hello, world!\n");$
$
$ cc -xc -o t t.c
t.c: In function ‘main’:
t.c:6:1: error: expected declaration or statement at end of input
6 | { printf("Hello, world!\n");
| ^
---
$ cat t.py
#!/usr/bin/python
if (x == 10)$
$
$ python t.py
File "/tmp/im/t.py", line 3
if (x == 10)
^
SyntaxError: expected ':'
===
* In above examples, files terminate without completing the statement and/or function definition (missing closing brace '}'), which is being treated as an error.
>Could you give me an example programming language
>that errors out when \n is missing at the end of the
>source file?
* It is not about '\n' at the end of file, but '\n' at the end of the Kconfig statement/record. Because Kconfig language uses EOL as a separator.
> I do not think requiring EOL at the end of file would help simplify the lexer/parser.
* It does, because on the parser side you don't have to define rule(s) with EOF to parse statements.
>When the lexer is encountered with EOF, it must
>tell the parser to finish the current statement
>and go back to the previous source file.
>So, EOF implies the end of the statement anyway.
* No, EOF does not imply end of a statement. The errors reported by gcc(1) and Python above clearly confirm that EOF is not end of statement.
* In their case colon(':') or brace ('}') are the required terminators, whereas in Kconfig's case EOL ('\n') is the required terminator.
* Because Kconfig language uses EOL ('\n') as statement separator/terminator, IMHO it should display an error when that condition is not met, because such statement remains incomplete.
Thank you.
---
-Prasad
