dependencies: Fix two more edge-cases in dependency searching

Includes tests for both of them.

mesonbuild/interpreter.py

@@ -1882,25 +1882,24 @@ class Interpreter(InterpreterBase):
             # was found already.
             # We only return early if we find a usable cached dependency since
             # there might be multiple cached dependencies like this.
-            w = identifier[1]
+            wanted = identifier[1]
             for trial, trial_dep in self.coredata.deps.items():
                 # trial[1], identifier[1] are the version requirements
                 if trial[0] != identifier[0] or trial[2:] != identifier[2:]:
                     continue
-                # The version requirements are the only thing that's different.
                 if trial_dep.found():
-                    # Cached dependency was found. We're close.
-                    f = trial_dep.get_version()
-                    if not w or mesonlib.version_compare_many(f, w)[0]:
-                        # We either don't care about the version, or the
-                        # cached dep version matches our requirements! Yay!
+                    found = trial_dep.get_version()
+                    if not wanted or mesonlib.version_compare_many(found, wanted)[0]:
+                        # We either don't care about the version, or our
+                        # version requirements matched the trial dep's version,
+                        # and the trial dep was a found dep!
                         return identifier, trial_dep
-                elif 'fallback' not in kwargs:
-                    # this cached dependency matched everything but was
-                    # not-found. Tentatively set this as the dep to use.
-                    # If no other cached dep matches, we will use this as the
-                    # not-found dep.
+                elif not trial[1]:
+                    # If the not-found cached dep did not have any version
+                    # requirements, this probably means the external dependency
+                    # cannot be found.
                     cached_dep = trial_dep
+                    break
         # There's a subproject fallback specified for this not-found dependency
         # which might provide it, so we must check it.
         if cached_dep and not cached_dep.found() and 'fallback' in kwargs:

test cases/linuxlike/5 dependency versions/meson.build

@@ -62,11 +62,24 @@ assert(somefail_dep.found() == false, 'somefail_dep found via wrong fallback')
 fallbackzlib_dep = dependency('zlib',
   fallback : ['somelib', 'fakezlib_dep'])
 assert(fallbackzlib_dep.type_name() == 'pkgconfig', 'fallbackzlib_dep should be of type "pkgconfig", not ' + fallbackzlib_dep.type_name())
-# Check that the above dependency was not found because it wasn't checked, not because the fallback didn't work
+# Check that the above dependency was pkgconfig because the fallback wasn't
+# checked, not because the fallback didn't work
 fakezlib_dep = dependency('fakezlib',
   fallback : ['somelib', 'fakezlib_dep'])
 assert(fakezlib_dep.type_name() == 'internal', 'fakezlib_dep should be of type "internal", not ' + fakezlib_dep.type_name())
 
+# Check that you can find a dependency by not specifying a version after not
+# finding it by specifying a version. We add `static: true` here so that the
+# previously cached zlib dependencies don't get checked.
+dependency('zlib', static : true, version : '>=8000', required : false)
+dependency('zlib', static : true)
+
+# Check that you can find a dependency by specifying a correct version after
+# not finding it by specifying a wrong one. We add `method: pkg-config` here so that
+# the previously cached zlib dependencies don't get checked.
+bzip2 = dependency('zlib', method : 'pkg-config', version : '>=9000', required : false)
+bzip2 = dependency('zlib', method : 'pkg-config', version : '>=1.0')
+
 if meson.is_cross_build()
   # Test caching of native and cross dependencies
   # https://github.com/mesonbuild/meson/issues/1736