The hunk header pattern 'cpp' is intended for C and C++ source code, but
it is actually not particularly useful for the latter, and even misses
some use-cases for the former.
The parts of the pattern have the following flaws:
- The first part matches an identifier followed immediately by a colon
and arbitrary text and is intended to reject goto labels and C++
access specifiers (public, private, protected). But this pattern also
rejects C++ constructs, which look like this:
MyClass::MyClass()
MyClass::~MyClass()
MyClass::Item MyClass::Find(...
- The second part matches an identifier followed by a list of qualified
names (i.e. identifiers separated by the C++ scope operator '::')
separated by space or '*' followed by an opening parenthesis (with
space between the tokens). It matches function declarations like
struct item* get_head(...
int Outer::Inner::Func(...
Since the pattern requires at least two identifiers, GNU-style
function definitions are ignored:
void
func(...
Moreover, since the pattern does not allow punctuation other than '*',
the following C++ constructs are not recognized:
. template definitions:
template<class T> int func(T arg)
. functions returning references:
const string& get_message()
. functions returning templated types:
vector<int> foo()
. operator definitions:
Value operator+(Value l, Value r)
- The third part of the pattern finally matches compound definitions.
But it forgets about unions and namespaces, and also skips single-line
definitions
struct random_iterator_tag {};
because no semicolon can occur on the line.
Change the first pattern to require a colon at the end of the line
(except for trailing space and comments), so that it does not reject
constructor or destructor definitions.
Notice that all interesting anchor points begin with an identifier or
keyword. But since there is a large variety of syntactical constructs
after the first "word", the simplest is to require only this word and
accept everything else. Therefore, this boils down to a line that begins
with a letter or underscore (optionally preceded by the C++ scope
operator '::' to accept functions returning a type anchored at the
global namespace). Replace the second and third part by a single pattern
that picks such a line.
This has the following desirable consequence:
- All constructs mentioned above are recognized.
and the following likely desirable consequences:
- Definitions of global variables and typedefs are recognized:
int num_entries = 0;
extern const char* help_text;
typedef basic_string<wchar_t> wstring;
- Commonly used marco-ized boilerplate code is recognized:
BEGIN_MESSAGE_MAP(CCanvas,CWnd)
Q_DECLARE_METATYPE(MyStruct)
PATTERNS("tex",...)
(The last one is from this very patch.)
but also the following possibly undesirable consequence:
- When a label is not on a line by itself (except for a comment) it is
no longer rejected, but can appear as a hunk header if it occurs at
the beginning of a line:
next:;
IMO, the benefits of the change outweigh the (possible) regressions by a
large margin.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Most of the tests show C++ code, but there is also a union definition and
a GNU style function definition that are not recognized.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A later patch changes the built-in cpp pattern. These test cases
demonstrate aspects of the pattern that we do not want to change.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
For the test case "matches to end of line", extend the pattern by a few
wildcards so that the pattern captures the "RIGHT" token, which is needed
for verification, without mentioning it in the pattern.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is one subtlety: The old test case 'perl pattern gets full line of
POD header' does not have its own new test case, but the feature is
tested nevertheless by placing the RIGHT tag at the end of the expected
hunk header in t4018/perl-skip-sub-in-pod.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add an infrastructure that simplifies adding new tests of the hunk
header regular expressions.
To add new tests, a file with the syntax to test can be dropped in the
directory t4018. The README file explains how a test file must contain;
the README itself tests the default behavior.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
