Resolved an issue with incorrect path resolution when linking static libraries via the build_flags // Resolve #5004

HISTORY.rst

@@ -22,6 +22,7 @@ test-driven methodologies, and modern toolchains for unrivaled success.
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 * Resolved an issue where the ``compiledb`` target failed to properly escape compiler executable paths containing spaces (`issue #4998 <https://github.com/platformio/platformio-core/issues/4998>`_)
+* Resolved an issue with incorrect path resolution when linking static libraries via the `build_flags <https://docs.platformio.org/en/latest/projectconf/sections/env/options/build/build_flags.html>`__ option (`issue #5004 <https://github.com/platformio/platformio-core/issues/5004>`_)
 
 6.1.16 (2024-09-26)
 ~~~~~~~~~~~~~~~~~~~

platformio/builder/tools/piobuild.py

@@ -219,6 +219,11 @@ def ParseFlagsExtended(env, flags):  # pylint: disable=too-many-branches
             if os.path.isdir(p):
                 result[k][i] = os.path.abspath(p)
 
+    # fix relative LIBs
+    for i, l in enumerate(result.get("LIBS", [])):
+        if isinstance(l, FS.File):
+            result["LIBS"][i] = os.path.abspath(l.get_path())
+
     # fix relative path for "-include"
     for i, f in enumerate(result.get("CCFLAGS", [])):
         if isinstance(f, tuple) and f[0] == "-include":