Add Rust documentation

This patch adds documentation for the new Rust support in gdb.

2016-05-17  Tom Tromey  <tom@tromey.com>

	* NEWS: Add Rust item.

2016-05-17  Tom Tromey  <tom@tromey.com>

	* gdb.texinfo (Supported Languages): Mention Rust.  Update menu.
	(Rust): New node.
This commit is contained in:
Tom Tromey 2016-04-26 19:38:56 -06:00
parent 67218854b1
commit 0bdfa368bc
4 changed files with 109 additions and 1 deletions

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@ -1,3 +1,7 @@
2016-05-17 Tom Tromey <tom@tromey.com>
* NEWS: Add Rust item.
2016-05-17 Tom Tromey <tom@tromey.com>
Manish Goregaokar <manishsmail@gmail.com>

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@ -27,6 +27,11 @@
Bounds: [lower = 0x7fffffffc390, upper = 0x7fffffffc3a3]
0x0000000000400d7c in upper () at i386-mpx-sigsegv.c:68
* Rust language support.
GDB now supports debugging programs written in the Rust programming
language. See https://www.rust-lang.org/ for more information about
Rust.
* New commands
skip -file file

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@ -1,3 +1,8 @@
2016-05-17 Tom Tromey <tom@tromey.com>
* gdb.texinfo (Supported Languages): Mention Rust. Update menu.
(Rust): New node.
2016-05-17 Tom Tromey <tom@tromey.com>
* gdb.texinfo (Maintenance Commands): Document "maint selftest".

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@ -14399,7 +14399,7 @@ being set automatically by @value{GDBN}.
@section Supported Languages
@value{GDBN} supports C, C@t{++}, D, Go, Objective-C, Fortran, Java,
OpenCL C, Pascal, assembly, Modula-2, and Ada.
OpenCL C, Pascal, Rust, assembly, Modula-2, and Ada.
@c This is false ...
Some @value{GDBN} features may be used in expressions regardless of the
language you use: the @value{GDBN} @code{@@} and @code{::} operators,
@ -14423,6 +14423,7 @@ language reference or tutorial.
* OpenCL C:: OpenCL C
* Fortran:: Fortran
* Pascal:: Pascal
* Rust:: Rust
* Modula-2:: Modula-2
* Ada:: Ada
@end menu
@ -15228,6 +15229,99 @@ The Pascal-specific command @code{set print pascal_static-members}
controls whether static members of Pascal objects are displayed.
@xref{Print Settings, pascal_static-members}.
@node Rust
@subsection Rust
@value{GDBN} supports the @url{https://www.rust-lang.org/, Rust
Programming Language}. Type- and value-printing, and expression
parsing, are reasonably complete. However, there are a few
peculiarities and holes to be aware of.
@itemize @bullet
@item
Linespecs (@pxref{Specify Location}) are never relative to the current
crate. Instead, they act as if there were a global namespace of
crates, somewhat similar to the way @code{extern crate} behaves.
That is, if @value{GDBN} is stopped at a breakpoint in a function in
crate @samp{A}, module @samp{B}, then @code{break B::f} will attempt
to set a breakpoint in a function named @samp{f} in a crate named
@samp{B}.
As a consequence of this approach, linespecs also cannot refer to
items using @samp{self::} or @samp{super::}.
@item
Because @value{GDBN} implements Rust name-lookup semantics in
expressions, it will sometimes prepend the current crate to a name.
For example, if @value{GDBN} is stopped at a breakpoint in the crate
@samp{K}, then @code{print ::x::y} will try to find the symbol
@samp{K::x::y}.
However, since it is useful to be able to refer to other crates when
debugging, @value{GDBN} provides the @code{extern} extension to
circumvent this. To use the extension, just put @code{extern} before
a path expression to refer to the otherwise unavailable ``global''
scope.
In the above example, if you wanted to refer to the symbol @samp{y} in
the crate @samp{x}, you would use @code{print extern x::y}.
@item
The Rust expression evaluator does not support ``statement-like''
expressions such as @code{if} or @code{match}, or lambda expressions.
@item
Tuple expressions are not implemented.
@item
The Rust expression evaluator does not currently implement the
@code{Drop} trait. Objects that may be created by the evaluator will
never be destroyed.
@item
@value{GDBN} does not implement type inference for generics. In order
to call generic functions or otherwise refer to generic items, you
will have to specify the type parameters manually.
@item
@value{GDBN} currently uses the C@t{++} demangler for Rust. In most
cases this does not cause any problems. However, in an expression
context, completing a generic function name will give syntactically
invalid results. This happens because Rust requires the @samp{::}
operator between the function name and its generic arguments. For
example, @value{GDBN} might provide a completion like
@code{crate::f<u32>}, where the parser would require
@code{crate::f::<u32>}.
@item
As of this writing, the Rust compiler (version 1.8) has a few holes in
the debugging information it generates. These holes prevent certain
features from being implemented by @value{GDBN}:
@itemize @bullet
@item
Method calls cannot be made via traits.
@item
Trait objects cannot be created or inspected.
@item
Operator overloading is not implemented.
@item
When debugging in a monomorphized function, you cannot use the generic
type names.
@item
The type @code{Self} is not available.
@item
@code{use} statements are not available, so some names may not be
available in the crate.
@end itemize
@end itemize
@node Modula-2
@subsection Modula-2