repository reorg

[mwhicks1]

Here's a bunch of non-code work to do on this repository:

Renames:

• [x] Replace all occurrences of cconv, CConv, CConvert, etc. in the codebase with 3c or 3C as appropriate. (Matt remembers this was agreed somewhere, but not where.) We agreed at the 2020-10-21 status meeting to prepend an underscore if 3C would be at the beginning of something that can't begin with a digit; it seems the least of several evils. Pending in #299.
• [x] Rename the clang/tools/cconv-standalone directory clang/tools/3c. Rename the build target cconv-standalone to 3c in the CMakeLists.txt file in that directory. Included in #299.
• Update tests and and nightly build actions to reference 3c and not cconv-standalone:
  • [x] #299 updates everything in the checkedc-clang repo.
  • The checkedc-eval* repos may need changes too: now tracked by #312, which Mike has agreed is no longer needed for the October 2020 milestone.

Documentation:

• [x] Update clang/docs/checkedc/3C.md. (More on READMEs below.)
• [x] Add README to clang/tools/3c directory, which points back to clang/docs/checkedc/3C.md.
• [x] Add a bit to the root README.md mentioning 3C as a subproject of Checked C (not to be confused with the root readme modification in #307).

Misc:

• [x] Plan to get rid of the tools/checked-c-convert directory. To do so, add a README that says this directory is out of date and scheduled for removal. (We will remove it when Microsoft is OK with that.)

clang/docs/checkedc/3C.md can talk at a high level of about the 3C tool and what it does and point out that there is the possibility of multiple front-ends for it, so most of the code is here, in a library. This file (or another MD in the same directory) can contain a basic overview of the code, running the regression tests, and some development guidelines.

The clang/tools/3c README can talk about how to run the tool, e.g., something about the command-line options, perhaps.

Some of the information we want to put in the new readmes may be available in our existing Google Docs, though perhaps not all.

[mattmccutchen-cci]

Plan to get rid of the tools/checked-c-convert directory. To do so, add a README that says this directory is out of date and scheduled for removal. (We will remove it when Microsoft is OK with that.)

The only thing in tools/checked-c-convert is a test case that looks like an old duplicate of this one. Another old duplicate of the test is the only thing in test/CheckedCRewriter. Can I just delete both old directories now?

[mwhicks1]

Yes, let's do it.

[mattmccutchen-cci]

I notice we currently have a readme at clang/docs/checkedc/CheckedCConvert.md (planned to be renamed to clang/docs/checkedc/3C.md). @mwhicks1 Is that a better location for the information we had previously planned to put in clang/lib/3C?

[mwhicks1]

I'm not sure. We should follow the conventions for tools that build on clang I would think. Is that where they put their docs too? @Machiry do you have an opinion?

[Machiry]

@mattmccutchen-cci is right. Lets put the documentation under clang/docs/checkedc/3C.md

[mattmccutchen-cci]

The last items were done in #323. I'll file separate issues as needed for improvements after the Microsoft PR.