[cmake-developers] Wrongly assuming lib/ is IsImplicitDirectory for runtime-paths

[Brad King]

On 05/15/2017 03:28 AM, Patrick Boettcher wrote:
> To this list somewhere the lib/-path located next to the
> compiler-bin/-path has been added.
[snip]
> What can I do? Is this a bug in cmake or in my setup?
> Why is this path considered implicit?

CMake tries to detect the implicit link directories used by the
compiler front-end when driving the linker.  See results in any
build tree:

```
$ grep IMPLICIT CMakeFiles/*/CMake*Compiler.cmake
```

The `Modules/CMakeParseImplicitLinkInfo.cmake` file contains the
code that does this.  It is called while detecting the compiler.

The assumption is that running `c++ foo.cpp && ./a.out` will work
with no special runtime paths explicitly added.  The toolchain
should be configured to add its own implicit link directories to
the runtime path of binaries it links, or the environment should
otherwise be configured such that the dynamic loader looks there.

-Brad