[auto_location][fix] Symlinks (#17421)

* Trusting the real path is the good one

* wip

conans/model/build_info.py

@@ -510,8 +510,7 @@ def _lib_match_by_regex(dir_, pattern):
                         # then os.path.realpath("libmylib.1.0.0.dylib") == "libmylib.dylib"
                         # Note: os.readlink() returns the path which the symbolic link points to.
                         real_path = os.path.realpath(full_path)
-                        if pattern.match(os.path.basename(real_path)):
-                            ret.add(real_path)
+                        ret.add(real_path)
                     else:
                         ret.add(full_path)
             return list(ret)

test/unittests/model/build_info/test_deduce_locations.py

@@ -160,26 +160,33 @@ def test_windows_several_shared_link_locations(lib_info, conanfile):
         assert result.components[f"_{lib_name}"].type == "shared-library"
 
 
+@pytest.mark.parametrize("lib, symlinks", [
+    # symlinks == "real_file <- symlink1 <- symlink2 <- ... <- symlinkN"
+    # Issue related: https://github.com/conan-io/conan/issues/17417
+    ("png", "libpng16.so.16.44.0 <- libpng16.so.16 <- libpng16.so <- libpng.so")
+])
 @pytest.mark.skipif(platform.system() == "Windows", reason="Can't apply symlink on Windows")
-def test_shared_link_locations_symlinks(conanfile):
+def test_shared_link_locations_symlinks(lib, symlinks, conanfile):
     """
     Tests auto deduce location is able to find the real path of
     any symlink created in the libs folder
     """
     folder = temp_folder()
+    all_files = symlinks.split(" <- ")  # [real_one, sym1, sym2, ...]
     # forcing a folder that it's not going to be analysed by the deduce_location() function
-    real_location = os.path.join(folder, "other", "mylib.so")
+    real_location = os.path.join(folder, "other", all_files.pop(0))
     save(real_location, "")
     # Symlinks
     os.makedirs(os.path.join(folder, "libdir"))
-    sym_1 = os.path.join(folder, "libdir", "mylib.1.0.0.so")
-    sym_2 = os.path.join(folder, "libdir", "mylib.2.0.0.so")
-    os.symlink(real_location, sym_1)
-    os.symlink(sym_1, sym_2)
+    prev_path = real_location
+    for file in all_files:
+        sym = os.path.join(folder, "libdir", file)
+        os.symlink(prev_path, sym)
+        prev_path = sym
 
     cppinfo = CppInfo()
     cppinfo.libdirs = ["libdir"]
-    cppinfo.libs = ["mylib"]
+    cppinfo.libs = [lib]
     cppinfo.set_relative_base_folder(folder)
 
     result = cppinfo.deduce_full_cpp_info(conanfile)