### Error: foobar at line 17 column 42.

The Bison front-end has detected a syntax error at the given location.
The error message is usually unusable, so let us hope the location is enough
for you to find what the problem is.

f(x) = x + 1;

Error: syntax error, unexpected '(', expecting FUNID or '=' at line 1 column 2

### Error: unrecognized option 'bar'.

Gappa was invoked with an unknown option.

Variant: unrecognized option 'bar' at line 42. This error is
displayed for options embedded in the script.

### Error: redefinition of identifier 'foo'...

A symbol cannot be defined more than once, even if the right hand sides
of every definitions are equivalent.

a = 1;
a = 1;

Nor can it be defined after being used as an unbound variable.

b = a * 2;
a = 1;

### Error: rounding operator expected, got 'foo'...

Only rounding operators (unary function close to the identity function)
can be prepended to the equal sign in a definition.

x add_rel<25,-100>= 1;

Error: rounding operator expected, got 'add_rel<25,-100>' at line 1 column 19

### Error: invalid parameters for 'foo'...

A function template has been instantiated with an incorrect number of
parameters or with parameters of the wrong type.

x = float<ieee_32,0>(y);

Error: invalid parameters for 'float' at line 1 column 20

### Error: incorrect number of arguments for 'foo'...

There are either less or more expressions between parentheses than
expected by the function.

x = int<zr>(y, z);

Error: incorrect number of arguments for 'fixed<0,zr>' at line 1 column 17