Merge branch 'fix/ldgen_template_fingerprint' into 'master'

fix(ldgen): add the linker template to the generation fingerprint

See merge request espressif/esp-idf!51620

tools/test_build_system/test_rebuild.py

@@ -183,6 +183,32 @@ def test_rebuild_ldgen_fingerprint(idf_py: IdfPyFunc, test_app_copy: Path) -> No
     assert skip_msg not in result.stdout, f'unexpected {skip_msg!r} in build output after fragment change'
 
 
+@pytest.mark.usefixtures('idf_copy')
+def test_rebuild_ldgen_template_change(idf_py: IdfPyFunc, test_app_copy: Path) -> None:
+    """Verify that a change to the linker script template reaches the generated
+    script. ldgen copies everything outside the mapping placeholders from the
+    template into its output verbatim, so the template is an input in its own
+    right and must not be hidden behind the fingerprint skip.
+    """
+    skip_msg = 'Skipping linker script generation, section names unchanged'
+    idf_path = Path(os.environ['IDF_PATH'])
+    template = idf_path / 'components/esp_system/ld/esp32/sections.ld.in'
+    generated = Path('build/esp-idf/esp_system/ld/sections.ld')
+    # An absolute symbol assignment: it is copied through to the generated
+    # script and does not depend on anything else in the build.
+    probe = '_ldgen_template_probe'
+
+    logging.info('initial build')
+    idf_py('build')
+
+    logging.info('adding a symbol to the template leaves section names and fragment files unchanged')
+    with open(template, 'a') as f:
+        f.write(f'\n{probe} = 0x3ff00abc;\n')
+    result = idf_py('build')
+    assert skip_msg not in result.stdout, f'unexpected {skip_msg!r} in build output after template change'
+    assert probe in generated.read_text(), 'template change did not reach the generated linker script'
+
+
 def test_rebuild_ldgen_lf_cache(idf_py: IdfPyFunc, test_app_copy: Path) -> None:
     """Verify the ldgen lf cache: when section names change but fragment files
     don't, parsed FragmentFile objects are loaded from cache rather than