[bug] Tools collect_libs discards suffixes

When porting the libpng project to Conan v2, the CCI hook complained that I lied about the library name in self.cpp_info.libs, which was supposed to be ["png16.a"] (on Linux/Mac is libpng16.a).

The truth is, the libpng projects creates a relative symbolic link, named as libpng.a, so we have two files in libdirs[0]: libpng16.a and its symlink libpng.a.

When writing the recipe, I avoided collect_libs and preferred and real name, so I pointed as:

self.cpp_info.libs = ["png16"] 

However, our CCI hook has a post cpp_info step which checks if what we declared for libs is actually installed in libdirs, and it failed. When checking the hook script, it uses collect_libs to list those installed libraries and compare with the libraries names from cpp_info. So, the method collect_libs only found "png", which means, it found the symbolic link, but ignored the real library.

Maybe it’s a expected behavior, as the symbolic link makes life easier to find the library, but still, it could be customized like collect_libs(self, ignore_symlinks=True) so, it would list only real files.

Environment Details (include every applicable attribute)

• Operating System+version: Linux and Mac confirmed
• Compiler+version: N/A
• Conan version: 1.51.3
• Python version: 3.10.4 (also tested with 3.9)

Steps to reproduce (Include if Applicable)

from conan import ConanFile
from conan.tools.files import collect_libs, save, mkdir
import os

class FooConan(ConanFile):
    def package(self):
        lib_folder = os.path.join(self.package_folder, "lib")
        lib_name = os.path.join(lib_folder, "libpng16.a")
        mkdir(self, lib_folder)
        save(self, lib_name, "FOOBAR")
        os.symlink(lib_name, os.path.join(lib_folder, "libpng.a"))

    def package_info(self):
        collected_libs = collect_libs(self)
        self.output.info(f"***** COLLECTED LIBS: {collected_libs}")
        self.cpp_info.libs = collected_libs
        # XXX: Collect libs only finds the symlink
        assert ["png"] == collected_libs

conan create . foo/0.1.0@ -pr:b=default -pr:h=default

Logs (Executed commands with output) (Include/Attach if Applicable)

Read the last lines of this log, the collected libs is there.

% conan create . foo/0.1.0@ -pr:b=default -pr:h=default
[HOOK - conan-center.py] pre_export(): [DEPRECATED GLOBAL CPPSTD (KB-H001)] OK
[HOOK - conan-center.py] pre_export(): [REFERENCE LOWERCASE (KB-H002)] OK
[HOOK - conan-center.py] pre_export(): ERROR: [RECIPE METADATA (KB-H003)] Conanfile doesn't have 'name' attribute. (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H003) 
[HOOK - conan-center.py] pre_export(): ERROR: [RECIPE METADATA (KB-H003)] Conanfile doesn't have 'url' attribute.  (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H003) 
[HOOK - conan-center.py] pre_export(): ERROR: [RECIPE METADATA (KB-H003)] Conanfile doesn't have 'license' attribute.  (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H003) 
[HOOK - conan-center.py] pre_export(): ERROR: [RECIPE METADATA (KB-H003)] Conanfile doesn't have 'description' attribute.  (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H003) 
[HOOK - conan-center.py] pre_export(): ERROR: [RECIPE METADATA (KB-H003)] Conanfile doesn't have 'homepage' attribute.  (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H003) 
[HOOK - conan-center.py] pre_export(): ERROR: [RECIPE METADATA (KB-H003)] Conanfile doesn't have 'topics' attribute.  (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H003) 
[HOOK - conan-center.py] pre_export(): WARN: [HEADER_ONLY, NO COPY SOURCE (KB-H005)] This recipe is a header only library as it does not declare 'settings'. Please include 'no_copy_source' to avoid unnecessary copy steps
[HOOK - conan-center.py] pre_export(): [HEADER_ONLY, NO COPY SOURCE (KB-H005)] OK
[HOOK - conan-center.py] pre_export(): [FPIC OPTION (KB-H006)] OK
[HOOK - conan-center.py] pre_export(): [VERSION RANGES (KB-H008)] OK
[HOOK - conan-center.py] pre_export(): [RECIPE FOLDER SIZE (KB-H009)] Total recipe size: 1.0537109375 KB
[HOOK - conan-center.py] pre_export(): [RECIPE FOLDER SIZE (KB-H009)] OK
[HOOK - conan-center.py] pre_export(): [EXPORT LICENSE (KB-H023)] exports: None
[HOOK - conan-center.py] pre_export(): [EXPORT LICENSE (KB-H023)] exports: None
[HOOK - conan-center.py] pre_export(): [EXPORT LICENSE (KB-H023)] OK
[HOOK - conan-center.py] pre_export(): ERROR: [TEST PACKAGE FOLDER (KB-H024)] There is no 'test_package' for this recipe (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H024) 
[HOOK - conan-center.py] pre_export(): [META LINES (KB-H025)] OK
[HOOK - conan-center.py] pre_export(): [CONAN CENTER INDEX URL (KB-H027)] OK
[HOOK - conan-center.py] pre_export(): [CMAKE MINIMUM VERSION (KB-H028)] OK
[HOOK - conan-center.py] pre_export(): [TEST PACKAGE - RUN ENVIRONMENT (KB-H029)] OK
[HOOK - conan-center.py] pre_export(): [SYSTEM REQUIREMENTS (KB-H032)] OK
[HOOK - conan-center.py] pre_export(): [CONANDATA.YML FORMAT (KB-H030)] OK
[HOOK - conan-center.py] pre_export(): [TEST PACKAGE - NO IMPORTS() (KB-H034)] OK
[HOOK - conan-center.py] pre_export(): [NO AUTHOR (KB-H037)] OK
[HOOK - conan-center.py] pre_export(): [NOT ALLOWED ATTRIBUTES (KB-H039)] OK
[HOOK - conan-center.py] pre_export(): [NO TARGET NAME (KB-H040)] OK
[HOOK - conan-center.py] pre_export(): [NO FINAL ENDLINE (KB-H041)] OK
[HOOK - conan-center.py] pre_export(): [NO REQUIRES.ADD() (KB-H044)] OK
[HOOK - conan-center.py] pre_export(): [DELETE OPTIONS (KB-H045)] OK
[HOOK - conan-center.py] pre_export(): [CMAKE VERBOSE MAKEFILE (KB-H046)] OK
[HOOK - conan-center.py] pre_export(): [CMAKE VERSION REQUIRED (KB-H048)] OK
[HOOK - conan-center.py] pre_export(): [CMAKE WINDOWS EXPORT ALL SYMBOLS (KB-H049)] OK
[HOOK - conan-center.py] pre_export(): [DEFAULT OPTIONS AS DICTIONARY (KB-H051)] OK
[HOOK - conan-center.py] pre_export(): [CONFIG.YML HAS NEW VERSION (KB-H052)] OK
[HOOK - conan-center.py] pre_export(): [PRIVATE IMPORTS (KB-H053)] OK
[HOOK - conan-center.py] pre_export(): [SINGLE REQUIRES (KB-H055)] OK
[HOOK - conan-center.py] pre_export(): [TOOLS RENAME (KB-H057)] OK
[HOOK - conan-center.py] pre_export(): [ILLEGAL CHARACTERS (KB-H058)] OK
[HOOK - conan-center.py] pre_export(): [CLASS NAME (KB-H059)] OK
[HOOK - conan-center.py] pre_export(): [NO CRLF (KB-H060)] OK
[HOOK - conan-center.py] pre_export(): [NO BUILD SYSTEM FUNCTIONS (KB-H061)] OK
[HOOK - conan-center.py] pre_export(): [TOOLS CROSS BUILDING (KB-H062)] OK
[HOOK - conan-center.py] pre_export(): [INVALID TOPICS (KB-H064)] OK
[HOOK - conan-center.py] pre_export(): [NO REQUIRED_CONAN_VERSION (KB-H065)] OK
[HOOK - conan-center.py] pre_export(): [TEST_TYPE MANAGEMENT (KB-H068)] OK
[HOOK - conan-center.py] pre_export(): [TEST PACKAGE - NO DEFAULT OPTIONS (KB-H069)] OK
[HOOK - conan-center.py] pre_export(): WARN: [MANDATORY SETTINGS (KB-H070)] No 'settings' detected in your conanfile.py. Add 'settings' attribute and use 'package_id(self)' method to manage the package ID.
[HOOK - conan-center.py] pre_export(): [MANDATORY SETTINGS (KB-H070)] OK
Exporting package recipe
[HOOK - conan-center.py] post_export(): [CONANDATA.YML REDUCE (KB-H031)] OK
[HOOK - conan-center.py] post_export(): [DEFAULT SHARED OPTION VALUE (KB-H050)] OK
[HOOK - conan-center.py] post_export(): [LICENSE PUBLIC DOMAIN (KB-H056)] OK
foo/0.1.0: The stored package has not changed
foo/0.1.0: Using the exported files summary hash as the recipe revision: 618bfcde05f3183716ed6832be4463a6 
foo/0.1.0: Exported revision: 618bfcde05f3183716ed6832be4463a6
Configuration (profile_host):
[settings]
arch=armv8
arch_build=armv8
build_type=Release
compiler=apple-clang
compiler.libcxx=libc++
compiler.version=13
os=Macos
os_build=Macos
[options]
[build_requires]
[env]
[conf]

Configuration (profile_build):
[settings]
arch=armv8
arch_build=armv8
build_type=Release
compiler=apple-clang
compiler.libcxx=libc++
compiler.version=13
os=Macos
os_build=Macos
[options]
[build_requires]
[env]
[conf]

foo/0.1.0: Forced build from source
Installing package: foo/0.1.0
Requirements
    foo/0.1.0 from local cache - Cache
Packages
    foo/0.1.0:5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9 - Build

Installing (downloading, building) binaries...
foo/0.1.0: Copying sources to build folder
foo/0.1.0: Building your package in /Users/uilian/.conan/data/foo/0.1.0/_/_/build/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
foo/0.1.0: Generator txt created conanbuildinfo.txt
foo/0.1.0: Aggregating env generators
[HOOK - conan-center.py] pre_build(): [FPIC MANAGEMENT (KB-H007)] 'fPIC' option not found
[HOOK - conan-center.py] pre_build(): [FPIC MANAGEMENT (KB-H007)] OK
foo/0.1.0: Calling build()
foo/0.1.0: WARN: This conanfile has no build step
foo/0.1.0: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' built
foo/0.1.0: Build folder /Users/uilian/.conan/data/foo/0.1.0/_/_/build/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
foo/0.1.0: Generated conaninfo.txt
foo/0.1.0: Generated conanbuildinfo.txt
foo/0.1.0: Generating the package
foo/0.1.0: Package folder /Users/uilian/.conan/data/foo/0.1.0/_/_/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
foo/0.1.0: Calling package()
[HOOK - conan-center.py] post_package(): ERROR: [PACKAGE LICENSE (KB-H012)] No 'licenses' folder found in package: /Users/uilian/.conan/data/foo/0.1.0/_/_/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9  (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H012) 
[HOOK - conan-center.py] post_package(): [DEFAULT PACKAGE LAYOUT (KB-H013)] OK
[HOOK - conan-center.py] post_package(): ERROR: [MATCHING CONFIGURATION (KB-H014)] Package for Header Only does not contain artifacts with these extensions: ['h', 'h++', 'hh', 'hxx', 'hpp'] (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H014) 
[HOOK - conan-center.py] post_package(): ERROR: [MATCHING CONFIGURATION (KB-H014)] Packaged artifacts does not match the settings used: os=None, compiler=None (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H014) 
[HOOK - conan-center.py] post_package(): [SHARED ARTIFACTS (KB-H015)] OK
[HOOK - conan-center.py] post_package(): [PC-FILES (KB-H020)] OK
[HOOK - conan-center.py] post_package(): [CMAKE-MODULES-CONFIG-FILES (KB-H016)] OK
[HOOK - conan-center.py] post_package(): [PDB FILES NOT ALLOWED (KB-H017)] OK
[HOOK - conan-center.py] post_package(): [LIBTOOL FILES PRESENCE (KB-H018)] OK
[HOOK - conan-center.py] post_package(): [MS RUNTIME FILES (KB-H021)] OK
[HOOK - conan-center.py] post_package(): [SHORT_PATHS USAGE (KB-H066)] OK
[HOOK - conan-center.py] post_package(): [MISSING SYSTEM LIBS (KB-H043)] OK
foo/0.1.0 package(): Packaged 2 '.a' files: libpng16.a, libpng.a
foo/0.1.0: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' created
foo/0.1.0: Created package revision fceead34a403492c2294e026d9a318fa
foo/0.1.0: ***** COLLECTED LIBS: ['png']
[HOOK - conan-center.py] post_package_info(): [CMAKE FILE NOT IN BUILD FOLDERS (KB-H019)] OK
[HOOK - conan-center.py] post_package_info(): [LIBRARY DOES NOT EXIST (KB-H054)] OK
[HOOK - conan-center.py] post_package_info(): ERROR: [INCLUDE PATH DOES NOT EXIST (KB-H071)] Component foo::foo include dir 'include' is listed in the recipe, but not found in package folder. The include dir should probably be fixed or removed. (https://github.com/conan-io/conan-center-index/blob/master/docs/error_knowledge_base.md#KB-H071) 

[memsharded]

In libpng recipe cpp_info.libs can be set to png[d] (or libpng[d] if msvc), which I think is neater anyway.

I think that if a recipe has some relatively simple logic that makes explicit the name of the final libraries, that is much preferred over a collect_libs. I know it is more effort on the recipe creator side, but following the python zen, explicit is better than implicit.

[SpaceIm]

The hook is useful, but indeed https://github.com/conan-io/conan/pull/11527 broke it since it was relying on previous behavior of collect_libs where everything with .lib, .so, .a, .dylib extensions was collected (it’s worth noting that this previous behavior didn’t collect .so.<version> files). The hook should be updated to still being able to find all files under the libdirs, and be happy if libs in cpp_info.libs match at list one of those files.

In libpng recipe cpp_info.libs can be set to png[d] (or libpng[d] if msvc), which I think is neater anyway.