69289 - |Substring| doesn't compile on gcc 2.7.2.3

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

The |Substring| function (defined as an overloaded pair of function templates in
nsAReadableString.h) doesn't compile on gcc 2.7.2.3 if the first argument needs
a conversion to get to |basic_nsAReadableString<charT>&|.  This causes bustage
and has been fixed in the tree both with NS_READABLE_CAST and with direct
construction of an nsPromiseSubstring<charT>.  It gives the error:

/builds/seamonkey/mozilla/netwerk/protocol/about/src/nsAboutProtocolHandler.cpp:139:
type unification failed for function template `template <class CharT>
nsPromiseSubstring<...> Substring(basic_nsAReadableString<...> &, unsigned int,
unsigned int)'

If I comment out the first of the two overloaded function templates, it gives
the error:

/builds/seamonkey/mozilla/netwerk/protocol/about/src/nsAboutProtocolHandler.cpp:139:
type unification failed for function template `template <class CharT>
nsPromiseSubstring<...> Substring(basic_nsAReadableString<...> &,
nsReadingIterator<...> &, nsReadingIterator<...> &)'


If I change nsAReadableString.h to un-templatize the function (i.e., just
provide 2 versions of each, one for charT == char and one for charT ==
PRUnichar), it compiles without NS_READABLE_CAST.

Perhaps we should do this to avoid bustage, perhaps based on some autoconf test
(although I don't think it would do any harm for other platforms...)?

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Scratch that un-templatizing suggestion -- it didn't link, at least not with gcc
2.96 (RH).

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Oops!  The linker errors were because I forgot to declare the functions |inline|.

Comment 3

[Scott Collins]

OK, the un-templatizing scheme sounds like the right thing to do then.

Comment 4

[Scott Collins]

See patch in bug #69940.

Comment 5

[Chris Waterson]

[r|sr]=waterson, pick one.

Comment 6

[Scott Collins]

patch (from bug #69940) checked in.