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/ldgen/ldgen.py

@@ -41,7 +41,7 @@ class MutuallyExclusiveEatAllOption(MutuallyExclusiveOption, OptionEatAll):
 _RE_SECTION_NAME = re.compile(r'^\s*\d+\s+(\.\S+)', re.MULTILINE)
 
 
-def _compute_fingerprint(sections_infos, fragment_files, config_file, kconfig_file):
+def _compute_fingerprint(sections_infos, fragment_files, config_file, kconfig_file, input_file):
     """Compute a fingerprint from section names and mtimes of all inputs."""
     hasher = hashlib.md5()
 
@@ -50,9 +50,12 @@ def _compute_fingerprint(sections_infos, fragment_files, config_file, kconfig_fi
         names = _RE_SECTION_NAME.findall(info.content)
         hasher.update((archive + ':' + ','.join(names)).encode())
 
-    # Mtimes of fragment files, sdkconfig, kconfig
+    # Mtimes of fragment files, the linker template, sdkconfig, kconfig. The
+    # template counts as an input because everything outside its mapping
+    # placeholders ends up in the generated script verbatim, so an edit to it
+    # changes the output even when no section name does.
     input_files = [p.name if hasattr(p, 'name') else p for p in fragment_files]
-    input_files += [p for p in (config_file, kconfig_file) if p]
+    input_files += [p.name if hasattr(p, 'name') else p for p in (input_file, config_file, kconfig_file) if p]
     for path in input_files:
         try:
             hasher.update(f'{path}:{os.path.getmtime(path)}'.encode())
@@ -190,7 +193,9 @@ def _run(
         # Check if we can skip generation entirely — section names and other
         # inputs unchanged since last run.
         fingerprint = (
-            None if no_cache else _compute_fingerprint(sections_infos, fragment_files, config_file, kconfig_file)
+            None
+            if no_cache
+            else _compute_fingerprint(sections_infos, fragment_files, config_file, kconfig_file, input_file)
         )
         if (
             output_path

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