Error while trying to load a compilation database:

Clang Frontend
#1

Hi All,

How do I get rid of this error ?

CX08$ /home/phi/llvmbuild/bin/clang-tidy -fix-errors -checks=‘readability-braces-around-statements’ c.c
Error while trying to load a compilation database:
Could not auto-detect compilation database for file “c.c”
No compilation database found in /home/phi or any parent directory
json-compilation-database: Error while opening JSON database: No such file or directory

Thanx in advance

Cheers,

Phi

#2

Hi,

Please, provide more datailed explanation of your issue. Which one of the following is it?

a) You have a compilation database in place and clang-tidy does not detect it.
b) You don’t have a compilation database.

If it’s b) you obviously can get rid of this error by getting a compilation database (on how to refer to Running Clang Tidy on LLVM).

Generally you might not always want to have a compilation database if your goal is just to analyze a single source file: this error doesn’t prevent clang-tidy from inspecting the provided sourcefile, so you’ll still get your diagnostics even if no compilation database is up.

Hope this helps,
Kirill Bobyrev

#3

​Thanx for yout reply.

I am in b) I don’t have a DB.

I red some docco on llvm , I did

CX08$ clang-tidy -dump-config >.clang-tidy

But it didn’t solved anything what I guess is normal .clang.tidy seems to be a configuration file.

I don’t know what is a DB, sonds like I need to run Cmake but I don’t know that at the moment (only know make). I ‘try’ clang-tidy and clang-format, first locally on a couple of files, then later on a bunch of files.

Cheers,

Phi

#4

​So far I understand that Cmake is related with building llvm, while I try to use clang-tidy on my own .c file not related with llvm (located on my login dir)

So I don’t really got it for now.

#5

​Thanx for yout reply.

I am in b) I don't have a DB.

I red some docco on llvm , I did

CX08$ clang-tidy -dump-config >.clang-tidy

But it didn't solved anything what I guess is normal .clang.tidy seems
to be a configuration file.

I don't know what is a DB, sonds like I need to run Cmake but I don't
know that at the moment (only know make). I 'try' clang-tidy and
clang-format, first locally on a couple of files, then later on a bunch
of files.

http://clang.llvm.org/docs/JSONCompilationDatabase.html

As an alternative to using a compilation database, you could also use the `--` flag. Suppose your normal clang command-line was:

   $ clang -fblocks foo.c

Then your clang-tidy command-line would be something like:

   $ clang-tidy foo.c -checks=* -- -fblocks foo.c

Where the set of arguments that go after the `--` is just the same set you would have normally passed to clang.

Jon

#6

​Thanx Jon
It works !! :slight_smile:
One last 'cosmetic' is there a way to have -fix-errors producing another
file instead of trashing the source file, or to have a backup of the
original file, so basically tidy c.c would produce c.c.new and leave c.c
intact OR tidy c.c would backup c.c into c.c.back and patch c.c

I don't remember. I'd check `clang-tidy -help`, or put the relevant source files in version control (or both).

Jon