mercurial/bdiff.h

extensions: ignore exceptions from an extension's `getversion()` method

This method is usually called when there's a stacktrace being generated, or with
`hg version -v`.  Raising another exception risks mangling the bug report info.

I hit this issue when trying to add the method to the keyring extension to
report the version of the extension and the underlying module, and ran into
demandimport issues prior to py3.8.  It seems like a wise thing to do anyway,
though unfortunately there's no convenient `ui` object around to issue a
warning.  Use 'unknown' to signal that it tried to report a version and failed,
unlike the default case of printing nothing.

Differential Revision: https://phab.mercurial-scm.org/D10540

#ifndef _HG_BDIFF_H_
#define _HG_BDIFF_H_

#include "compat.h"

struct bdiff_line {
	int hash, n, e;
	ssize_t len;
	const char *l;
};

struct bdiff_hunk;
struct bdiff_hunk {
	int a1, a2, b1, b2;
	struct bdiff_hunk *next;
};

int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr);
int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, int bn,
               struct bdiff_hunk *base);
void bdiff_freehunks(struct bdiff_hunk *l);

#endif