Add a flag to Stackframe that indicates where the stack frame is the
bottom-most frame of the stack. This allows clients to know whether the
stack trace terminated normally or if it was truncated because the
maximum depth was reached.
Add a truncation message to the 'stack' command.

Fncall.go was written with the assumption that the object returned by
proc.Thread.Registers does not change after we call
proc.Thread.SetPC/etc.

This is true for the native backend but not for gdbserial. I had
anticipated this problem and introduced the Save/SavedRegisters
mechanism during the first implementation of fncall.go but that's
insufficient.

Instead:

1. clarify that the object returned by proc.Thread.Registers could
   change when the CPU registers are modified.
2. add a Copy method to Registers that returns a copy of the registers
   that are guaranteed not to change when the CPU registers change.
3. remove the Save/SavedRegisters mechanism.

This solution leaves us the option, in the future, to cache the output
of proc.(Thread).Registers, avoiding a system call every time it's
called.

Implements missing functionality in gdbserial to enable function calls
on OSX.

Normally variables that have a named struct as a type will get a
typedef entry as their type, sometimes however the Go linker will
decide to use the DW_TAG_structure_type entry instead.

For consistency always wrap a struct type into a typedef when we are
creating a new variables (see comment in newVariable for exceptions).

This fixes a bug where it would be impossible to call methods on a
global variable.

Next should work even if one or more instructions in the current
function can not be disassembled.

Add new version to CHANGELOG and update internal version.

Thank you @jaym, @slp, @yasushi-saito, @acshekhara1, @benc153,
@yuval-k, @functionary, @psanford @giuscri, @jsoref, @Carpetsmoker,
@PatrickSchuster, @aarzilli, @derekparker, @ramya-rao-a and @dlsniper.

Updated call description to reflect current limitations.

Evaluates var.method expressions into a variable holding the
corresponding method with the receiver variable as a child, in
preparation for extending CallFunction so that it can call methods.

Changes (*Variable).setValue so that it can be used in CallFunction to
set up the argument frame for the function call, adding the ability to:
- nil nillable types
- set strings to the empty string
- copy from one structure to another (including strings and slices)
- convert any interface type to interface{}
- convert pointer shaped types (map, chan, pointers, and structs
  consisting of a single pointer field) to interface{}

This covers all cases where an assignment statement can be evaluated
without allocating memory or calling functions in the target process.

This patch makes it so inlined functions are returned in the
function
list, and also allows users to set breakpoints on the call site of
inlined functions.

Fixes #1261

Something changed on Travis side that broke TestIssue877. Disable that
test when $TRAVIS is set to true.

Which I miss from gdb-- it's nice to be able to open where you are in
your editor where you're already working on the project you're
debugging.

If we send a process to foreground while the headless instance may get
a SIGTTOU/SIGTTIN, if not ignored this signal will stop the headless.
It's not clear why this only happens the second time we do this but
that's how it is.

Also removes the direct syscall to TIOCSPGRP and lets the go runtime do
it instead.

Fixes #1279

Adds a test that compares the output of our state machine with the
output of the debug_line reader in the standard library and checks that
they produce the same output for the debug_line section of grafana as
compiled on macOS (which is the most interesting case since it uses cgo
and therefore goes through dsymutil).

A few bugs were uncovered and fixed:

1. is_stmt was reset improperly after a DW_LNS_end_sequence instruction
2. basic_block, prologue_end and epilogue_begin were not reset after a
   DW_LNS_copy instruction
3. some opcodes were not decoded properly if the debug_line section
   declares fewer standard opcodes than we know about.

Fixes #1282

Adds -defer flag to the stack command that decorates the stack traces
by associating each stack frame with its deferred calls.

Reworks proc.next to use this feature instead of using proc.DeferPC,
laying the groundwork to implement #1240.

next/step/stepout should work even if the current frame isn't the
topmost stack frame, but their behavior should be different in that
case (they should continue inside the function of the selected frame).

Most of the logic of next/step/stepout would work correctly if we
simply replaced the call to proc.topframe with something that took a
frame index. However the breakpoint they set on the first deferred
function is wrong, and fixing it requires scanning the defer stack and
matching it to the call stack, something we can't do yet.

Given that enhancing next/step/stepout will take time and the current
behavior confuses users (see issue #1240) return an error if
next/step/stepout are called while the currently selected frame isn't
frame 0.

Updates #1240

There is no guarantee that files will end up stored contiguously in the
debug_line section which makes this optimization wrong in the general
case.
In particular with recent versions of go1.11 and a go.mod file present
the go compiler seems to sometimes produce executables that actually
violate this assumption.

On newer kernels when /proc/sys/kernel/perf_event_paranoid is > 1 rr
will crash with SIGABRT. Return an error instead of letting this
happen.

Implements the function call injection protocol introduced in go 1.11
by https://go-review.googlesource.com/c/go/+/109699.

This is only the basic support, see TODO comments in pkg/proc/fncall.go
for a list of missing features.

Updates #119

Fixes a bug where breakpoint condition evaluation would never load the
value if the breakpoint condition consisted of just a single variable.

Fix #1264

Adds StartPC to proc.G, StartLoc to api.Goroutine and show the start
location in the command line client when appropriate.

Updates #1104

The JSON-RPC layer doesn't like non-nil error that return an empty string
when the Error method is called and when this happens it shuts down the
connection to the server.
Since we can return a ThreadBlockedError to the client it can't have an
empty string as return value.

Fixes #1251

Core files created by gdb can have sections missing that would be
present in OS created core files.

We work around this by first reading PT_LOAD entries from the exe and
then reading them from the core.

Fixes #1121

Setting the Level field of a logrus logger doesn't actually do anything
since the Level field simply reports the log level of the last log
message emitted on the logger.
The right way to do that is to set logger.Logger.Level.
Also cleans up newline characters from log messages emitted through
logrus and fixes the direction of the arrows in the messages emitted by
rpccommon, which was inconsistent with the arrows of gdbserial.

Adds a field, DeclLine, to Variable containing the declaration line
number of the variable.

This pull request makes several changes to delve to allow headless
instancess that are started with the --accept-multiclient flag to
keep running even if there is no connected client. Specifically:

1. Makes a headless instance started with --accept-multiclient quit
    after one of the clients sends a Detach request (previously they
    would never ever quit, which was a bug).
2. Changes proc/gdbserial and proc/native so that they mark the
    Process as exited after they detach, even if they did not kill the
    process during detach. This prevents bugs such as #1231 where we
    attempt to manipulate a target process after we detached from it.
3. On non --accept-multiclient instances do not kill the target
    process unless we started it or the client specifically requests
    it (previously if the client did not Detach before closing the
    connection we would kill the target process unconditionally)
4. Add a -c option to the quit command that detaches from the
    headless server after restarting the target.
5. Change terminal so that, when attached to --accept-multiclient,
    pressing ^C will prompt the user to either disconnect from the
    server or pause the target process. Also extend the exit prompt to
    ask if the user wants to keep the headless server running.

Implements #245, #952, #1159, #1231

Go1.11 switched to the zlib-gnu compression format for debug sections.
Change proc and and a test in dwarf/line to support this change.

Also deletes some dead code from pkg/proc/bininfo.go that hadn't been
used in a long time.

Implements structured logging via Logrus. This gives us a logger per
boundry that we care about, allowing for easier parsing of logs if users
have more than one log option enabled. Also, cleans up a lot of
conditionals in the code by simply silencing the logger at creation as
opposed to conditionally logging everywhere.

To save disk space, some distributions strip the debugging information
from the binaries, putting it in separate files, usually distributed in
separate packages.

To locate the file containing the debug information for a certain
binary, an ELF note named ".note.gnu.build-id" is added to the latter,
which contains a header and a build identification. This identification
can be used to compose a path with this form:

/usr/lib/debug/.build-id/BUILDID[:2]/BUILDID[2:].debug

With this patch, if Delve can't find the debug information in the main
binary, it'll try to locate and parse ".note.gnu.build-id", to compose
and attempt to open a path with the format described above.

Fixes #1206

A user complained on the mailing list about having continuous
"optimized function warnings" on non-optimized functions when using 1.9.
This commit fixes the problem by disabling optimized function detection
on 1.9 and earlier (where it's impossible) and adds a test so we don't
break it again in the future.

If the application being debugged imports two packages with the same
name (but different paths) there was no way to disambiguate the two,
since the character '/' can not appear inside a go identifier.

By allowing users to use a string literal as the package name a package
path can be specified.

We occasionally receive bug reports from users of VSCode-go and GoLand.
GoLand has its own way of capturing the packet exchange between itself
and delve but VSCode-go (supposedly) doesn't.
So far this hasn't been a problem since all bug reports were obvious
bugs on the plugin or easy to reproduce without VSCode-go, but it might
be helpful in the future to have a way to log the packet exchange
between dlv and a frontend.

This commit adds a --log-output option to enable logging of all rpc
messages and changes service/rpccommon accordingly.

Displays the return values of the current function when we step out of
it after executing a step, next or stepout command.

Implementation of this feature is tricky: when the function has
returned the return variables are not in scope anymore. Implementing
this feature requires evaluating variables that are out of scope, using
a stack frame that doesn't exist anymore.

We can't calculate the address of these variables when the
next/step/stepout command is initiated either, because between that
point and the time where the stepout breakpoint is actually hit the
goroutine stack could grow and be moved to a different memory address.

Add a new method "Common" to proc.Process that returns a pointer to a
struct that pkg/proc can use to store its things, independently of the
backend.

This is used here to replace the AllGCache typecasts, it will also be
used to store the return values of the stepout breakpoint and the state
for injected function calls.

Fixes #1227