Add a cheap & basic debug-info generation option

[huonw]

Previously we had -Z debug-info and -Z extra-debug-info where the first was essentially line-numbers only and the second was the full local variables etc. information. -Z extra-debug-info was replaced by -g and the former was removed.

A -Z debug-info equivalent has lower compilation and runtime overhead.

[huonw]

(Background: @alexcrichton said he removed -Z debug-info because he didn't realise there was a difference between it and -Z extra-debug-info.)

[alexcrichton]

The differences between the old extra_debuginfo and debuginfo options can be found as part of 071ee96. Sorry the diff is large, I assumed that these were the same thing and didn't realize they served different purposes!

[DiamondLovesYou]

Maybehaps -Z debug-info should be renamed to something like -Z line-info?

Richard Diamond

On Fri, Feb 14, 2014 at 5:25 PM, Alex Crichton notifications@github.comwrote:

The differences between the old extra_debuginfo and debuginfo options can
be found as part of 071ee96071ee96.
Sorry the diff is large, I assumed that these were the same thing and
didn't realize they served different purposes!

Reply to this email directly or view it on GitHubhttps://github.com//issues/12280#issuecomment-35136739
.

[DiamondLovesYou]

('cause I didn't know either)

Richard Diamond

On Fri, Feb 14, 2014 at 5:31 PM, Richard Diamond <
wichard@vitalitystudios.com> wrote:

Maybehaps -Z debug-info should be renamed to something like -Z line-info?

Richard Diamond

On Fri, Feb 14, 2014 at 5:25 PM, Alex Crichton notifications@github.comwrote:

The differences between the old extra_debuginfo and debuginfo options
can be found as part of 071ee96071ee96.
Sorry the diff is large, I assumed that these were the same thing and
didn't realize they served different purposes!

Reply to this email directly or view it on GitHubhttps://github.com//issues/12280#issuecomment-35136739
.

[jdm]

Clang has -gline-tables-only, which seems like reasonable prior art.

[michaelwoerister]

GCC has -g{level} where level is 0-3:
-g0 means no debug info.
-g1 is equivalent to -gline-tables-only.
-g2 is the same as just -g.
-g3 has some more debug info related to C macros.

I think that's rather nice and short to type but one has to remember more what's what. I'm not against -gline-tables-only but I think I'd prefer -g{0,1,2} with -g being the same as -g2.

[michaelwoerister]

@alexcrichton I just now saw that there is no more distinction between debug-info and extra-debug-info. Thanks for linking the change set here. Some of these changes need to be reverted/adapted if we want to have a line-tables-only version again (which shouldn't be much of a problem though).