2 ms·

That's interesting -- I was wondering in which cases typedef changes the parse tree, and came across a few [1]: a (b); /* function call or declaration

That's interesting -- I was wondering in which cases typedef changes the parse tree, and came across a few [1]: a (b); /* function call or declaration */ a * b; /* multiplication or declaration */ f((a) * b); /* multiplication or deref and cast */ > With one further change, namely deleting the production typedef-name: identifier and making typedef-name a terminal symbol, this grammar is acceptable to the YACC parser-generator. [1] http://eli.thegreenplace.net/2007/11/24/the-context-sensitivity-of-cs-grammar http://eli.thegreenplace.net/2007/11/24/the-context-sensitiv...

int_19h 10y ago
С++ takes it all the way to 11 with templates. Here's a program that is parsed differently depending on whether pointers are 32-bit or 64-bit: template<size_t N = sizeof(void*)> struct a; template<> struct a<4> { enum { b }; }; template<> struct a<8> { template<int> struct b {}; }; enum { c, d }; int main() { a<>::b<c>d; d; } Depending on which instantiation is used, the first line of main is either a variable declaration, or two operators < and > applied in sequence. This is especially fun to deal with for C++ IDEs that support semantic highlighting (i.e. typenames are in a different color etc). If I remember correctly, the first one that could handle this right was VS 2012 - it only took 14 years after ISO C++ standard was released...