We have a long history of INVALID bugs about std functions being
available in the global namespace (PRs 27846, 67566, 82619, 99865,
110602, 111553, probably others). Let's document it.
Also de-prioritize the C++98-only bugs, which are unlikely to affect
anybody nowadays.
OK for wwwdocs?
-- >8 --
Add ADL to C++ non-bugs
Also move the item about C++98 'export' to the end, and update the item
about <: digraphs that only applies to C++98.
---
htdocs/bugs/index.html | 36
1 file changed, 24 insertions(+), 12 deletions(-)
diff --git a/htdocs/bugs/index.html b/htdocs/bugs/index.html
index 813b78c0..41edc561 100644
--- a/htdocs/bugs/index.html
+++ b/htdocs/bugs/index.html
@@ -539,15 +539,15 @@ for details.
C++
-export
-Most C++ compilers (G++ included) never implemented C++98
-export, which was removed in C++11, and the keyword reused in
-C++20 by the Modules feature. The C++98 feature was intended to support
-separate compilation of template declarations and
-definitions. Without export, a template definition must be in
-scope to be used. The obvious workaround is simply to place all definitions in
-the header itself. Alternatively, the compilation unit containing template
-definitions may be included from the header.
+Functions can be called without qualifying them with their namespace.
+
+Argument Dependent Lookup (ADL) means that functions can be found in namespaces
+associated with their arguments. This means that move(arg) can
+call std::move if arg is a type defined in namespace
+std, such as std::string or std::vector.
+If std::move is not the function you intended to call, use a
+qualified name such as ::move(arg) or foo::move(arg).
+
Nested classes can access private members and types of the containing
class.
@@ -597,9 +597,9 @@ handler and catch it in the main thread.
If you have a class in the global namespace, say named X,
and want to give it as a template argument to some other class, say
std::vector, then std::vector::X
-fails with a parser error.
+fails with a parser error in C++98/C++03 mode.
-The reason is that the standard mandates that the sequence
+The reason is that the C++98 standard mandates that the sequence
: is treated as if it were the token [.
(There are several such combinations of characters - they are called
digraphs.) Depending on the version, the compiler then reports
@@ -608,7 +608,19 @@ a parse error before the character : (the
colon before
The simplest way to avoid this is to write std::vector
::X, i.e. place a space between the opening angle bracket
-and the scope operator.
+and the scope operator, or compile using C++11 or later. Defect report 1104
+changed the parser rules so that :: works as expected.
+
+
+export
+Most C++ compilers (G++ included) never implemented C++98
+export, which was removed in C++11, and the keyword reused in
+C++20 by the Modules feature. The C++98 feature was intended to support
+separate compilation of template declarations and
+definitions. Without export, a template definition must be in
+scope to be used. The obvious workaround is simply to place all definitions in
+the header itself. Alternatively, the compilation unit containing template
+definitions may be included from the header.
Common problems when upgrading the compiler
--
2.41.0
