Overhaul pkg-config and CMake lookup, fixing the latter

First, I noticed there was a dangling use of now-removed cross_info in
the CMake lookup. No tests had caught this, but it means that CMake deps
were totally broken. [It also meant that CMake could not be specified
from a native file.]

In a previous of mine PR which removed cross_info, I overhauled finding
pkg-config a bit so that the native and cross paths were shared. I
noticed that the CMake code greatly resembled the pkg-config code, so I
set about fixing it to match.

I then realized I could refactor things further, separating caching,
finding alternatives, and validating them, while also making the
validations less duplicated. So I ended up changing pkg config lookup a
lot too (and CMake again, to keep matching).

Overall, I think I have the proper ideom for tool lookup now, repated in
two places. I think it would make sense next to share this logic between
these two, compilers, static linkers, and any other tool similarly
specifiable. Either the `BinaryTable` class in environment.py, or a new
class for `Compiler` and friends to subclass, would be good candidates
for this.

1 files changed, 2 insertions, 0 deletions

diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index ad279be..30d5912 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -433,6 +433,7 @@ class Environment:
         self.cuda_static_linker = ['nvlink']
         self.gcc_static_linker = ['gcc-ar']
         self.clang_static_linker = ['llvm-ar']
+        self.default_cmake = ['cmake']
         self.default_pkgconfig = ['pkg-config']
 
         # Various prefixes and suffixes for import libraries, shared libraries,
@@ -1503,6 +1504,7 @@ class BinaryTable:
         'ar': 'AR',
         'windres': 'WINDRES',
 
+        'cmake': 'CMAKE',
         'pkgconfig': 'PKG_CONFIG',
     }