[esp8266] Force-include the throw stubs into the core and libraries on the native toolchain (#20336)

esphome/build_gen/arduino8266.py

@@ -54,6 +54,7 @@ from esphome.components.esp8266.const import (
     KEY_ESP8266,
     KEY_FLASH_SIZE,
     KEY_SCANF_FLOAT,
+    THROW_STUBS_HEADER,
 )
 from esphome.core import CORE, EsphomeError
 from esphome.framework_helpers import get_project_cxx_compile_flags
@@ -1087,32 +1088,8 @@ def write_project(paths: InstalledPaths, ccache: str | None) -> bool:
     if "USE_ESP8266_WAVEFORM_STUBS" in flag_defines:
         core_exclude |= _CORE_EXCLUDE_WAVEFORM
 
-    archives = []
-    # variant_dir existence was already enforced with the include dirs
-    variant_sources = collect_sources(variant_dir)
-    if variant_sources:
-        objs = compile_edges(lines, variant_sources, variant_dir, "variant")
-        lines.append(f"build libFrameworkArduinoVariant.a: ar {' '.join(objs)}")
-        archives.append("libFrameworkArduinoVariant.a")
-
-    core_objs = compile_edges(
-        lines, collect_sources(core_dir, core_exclude), core_dir, "core"
-    )
-    if not core_objs:
-        # An empty archive would link into a wall of undefined references
-        # (app_entry, the exception vectors) far from the cause
-        raise EsphomeError(
-            f"{_INCOMPLETE_INSTALL}: no core sources in {core_dir}; {_CLEAN_HINT}"
-        )
-    lines.append(f"build libFrameworkArduino.a: ar {' '.join(core_objs)}")
-    archives.append("libFrameworkArduino.a")
-
-    lib_archives, direct_objs = library_edges(lines, libraries)
-    archives += lib_archives
-
-    # One source of truth with the PlatformIO path: esp8266/__init__ pins
-    # build_src_flags (the throw_stubs force-include); -include paths
-    # resolve against the source root
+    # esp8266/__init__ pins build_src_flags (the throw_stubs force-include), as on
+    # the PlatformIO path; -include paths resolve against the source root
     src_other: list[str] = []
     src_includes: list[str] = []
     src_it = iter(
@@ -1131,7 +1108,45 @@ def write_project(paths: InstalledPaths, ccache: str | None) -> bool:
             src_includes.append(tok[len("-include") :])
         else:
             src_other.append(_shell_token(tok))
+    # The throw stubs abort: none anywhere with exceptions on, else the core and
+    # libraries get them too (src keeps them after its pch include)
+    if config.exceptions:
+        src_includes = [h for h in src_includes if h != THROW_STUBS_HEADER]
     include_flags = [f"-include {_q(src_dir / h)}" for h in src_includes]
+    framework_flags = ""
+    if THROW_STUBS_HEADER in src_includes:
+        stubs_flag = include_flags[src_includes.index(THROW_STUBS_HEADER)]
+        lines.append(f"frameworkflags = {stubs_flag}")
+        framework_flags = "$frameworkflags"
+    archives = []
+    # variant_dir existence was already enforced with the include dirs
+    variant_sources = collect_sources(variant_dir)
+    if variant_sources:
+        objs = compile_edges(
+            lines, variant_sources, variant_dir, "variant", flags=framework_flags
+        )
+        lines.append(f"build libFrameworkArduinoVariant.a: ar {' '.join(objs)}")
+        archives.append("libFrameworkArduinoVariant.a")
+
+    core_objs = compile_edges(
+        lines,
+        collect_sources(core_dir, core_exclude),
+        core_dir,
+        "core",
+        flags=framework_flags,
+    )
+    if not core_objs:
+        # An empty archive would link into a wall of undefined references
+        # (app_entry, the exception vectors) far from the cause
+        raise EsphomeError(
+            f"{_INCOMPLETE_INSTALL}: no core sources in {core_dir}; {_CLEAN_HINT}"
+        )
+    lines.append(f"build libFrameworkArduino.a: ar {' '.join(core_objs)}")
+    archives.append("libFrameworkArduino.a")
+
+    lib_archives, direct_objs = library_edges(lines, libraries, framework_flags)
+    archives += lib_archives
+
     # One shared variable instead of repeating the flags line on every src
     # edge (hundreds of edges in a real project)
     lines.append(f"srcflags = {' '.join(src_other + include_flags)}")

esphome/build_helpers/ninja_gen.py

@@ -207,10 +207,12 @@ def compile_edges(
 
 
 def library_edges(
-    lines: list[str], libraries: list[ArduinoLibrary]
+    lines: list[str], libraries: list[ArduinoLibrary], extra_flags: str = ""
 ) -> tuple[list[str], list[str]]:
     """Emit every library's compile and archive edges.
 
+    ``extra_flags`` (raw ninja text) precede each library's own flags.
+
     Returns the archive names and the objects that link directly. A
     library's own include dirs lead its compile lines, as PlatformIO searched
     them first: the include path is one global list, so another library's
@@ -232,7 +234,7 @@ def library_edges(
             lib.sources,
             common_parent(lib.sources),
             f"lib/{lib.name}",
-            flags=" ".join(_shell_token(f) for f in lib.flags),
+            flags=" ".join(filter(None, [extra_flags, *map(_shell_token, lib.flags)])),
             own_includes=" ".join(f"-I{_q(d)}" for d in lib.include_dirs),
         )
         if not lib.lib_archive:

esphome/components/esp8266/__init__.py

@@ -53,6 +53,7 @@ from .const import (
     KEY_SERIAL1_REQUIRED,
     KEY_SERIAL_REQUIRED,
     KEY_WAVEFORM_REQUIRED,
+    THROW_STUBS_HEADER,
     enable_serial,
     enable_serial1,
     esp8266_ns,
@@ -477,11 +478,9 @@ async def to_code(config: ConfigType) -> None:
 
     # Force-include inline std::__throw_* overrides so GCC dead-strips the unused
     # libstdc++ error message strings (e.g. "basic_string::_M_create") from DRAM.
-    # See throw_stubs.h. Unconditional: the native build generator reads
-    # the same option, keeping one source of truth.
-    cg.add_platformio_option(
-        "build_src_flags", "-include esphome/components/esp8266/throw_stubs.h"
-    )
+    # See throw_stubs.h. The native build generator reads this option, also
+    # passes it to the core and libraries, and drops it with exceptions on.
+    cg.add_platformio_option("build_src_flags", f"-include {THROW_STUBS_HEADER}")
 
     # In testing mode, fake larger memory to allow linking grouped component tests
     # Real ESP8266 hardware only has 32KB IRAM and ~80KB RAM, but for CI testing

esphome/components/esp8266/const.py

@@ -17,6 +17,8 @@ KEY_SERIAL_REQUIRED = "serial_required"
 KEY_SERIAL1_REQUIRED = "serial1_required"
 # Set for the native (non-PlatformIO) toolchain's build generator
 KEY_SCANF_FLOAT = "scanf_float"
+# Force-included std::__throw_* overrides, relative to the src dir
+THROW_STUBS_HEADER = "esphome/components/esp8266/throw_stubs.h"
 # Per-board flash-layout override consumed by board_ld_script()
 KEY_LDSCRIPT = "ldscript"
 # Crash-decode tools, resolved once per run by __init__

esphome/components/esp8266/throw_stubs.h

@@ -15,7 +15,8 @@
  * unused, dead-strip the load, and drop the string entirely -- no LTO needed.
  * Behavior is identical to today: a bare abort() (the message was never
  * printed). This header MUST be force-included before <string>, so it is
- * wired up via build_src_flags "-include ..." in this component's __init__.py.
+ * wired up via build_src_flags "-include ..." in this component's __init__.py;
+ * the native toolchain also force-includes it into the core and libraries.
  *
  * Note: this defines functions in namespace std (technically UB). It is safe
  * here because the definitions match the existing abort() behavior exactly.

tests/unit_tests/build_gen/test_arduino8266.py

@@ -34,7 +34,12 @@ from esphome.components.esp8266.boards import (
     board_ld_script,
 )
 from esphome.components.esp8266.build_surgery import RATETABLE_RULE
-from esphome.components.esp8266.const import KEY_BOARD, KEY_ESP8266, KEY_SCANF_FLOAT
+from esphome.components.esp8266.const import (
+    KEY_BOARD,
+    KEY_ESP8266,
+    KEY_SCANF_FLOAT,
+    THROW_STUBS_HEADER,
+)
 import esphome.config_validation as cv
 from esphome.const import KEY_CORE, KEY_FRAMEWORK_VERSION
 from esphome.core import CORE, EsphomeError
@@ -360,18 +365,22 @@ def test_write_project_link_line_and_exclusions(tmp_path: Path) -> None:
     # Assembly and C sources compile through their own rules
     assert "cont.S.o: aspp" in content
     assert "abi.c.o: c" in content
-    # throw_stubs is force-included for ESPHome sources only, via one shared
-    # srcflags variable rather than a copy of the flags line per edge
+    # throw_stubs reaches src through srcflags (after the pch include) and the
+    # core through frameworkflags: one shared variable each, not a copy per edge
     src_lines = [line for line in content.splitlines() if "obj/src/" in line]
     assert any("main.cpp.o: cxx" in line for line in src_lines)
-    assert content.count("throw_stubs.h") == 1
+    assert content.count("throw_stubs.h") == 2
     assert "srcflags = -include" in content
     flags_lines = [
         line for line in content.splitlines() if line.startswith("  flags = ")
     ]
     assert flags_lines
     # C++ src edges consume the precompiled header; C/assembly keep srcflags
-    assert set(flags_lines) == {"  flags = $srcflags", "  flags = $srccxxflags"}
+    assert set(flags_lines) == {
+        "  flags = $srcflags",
+        "  flags = $srccxxflags",
+        "  flags = $frameworkflags",
+    }
 
 
 def test_write_project_pch(tmp_path: Path) -> None:
@@ -715,6 +724,8 @@ def test_write_project_libraries_and_variant(
     assert "libHeadersOnly.a" not in content
     assert "Library HeadersOnly has no source files" in caplog.text
     assert "  flags = -DMYLIB=1" in content
+    # With exceptions on, nothing gets the stubs
+    assert "throw_stubs.h" not in content
     # A library's own include dirs lead its compile lines
     assert "  own_includes = -I" in content
     assert "$own_includes $cxxflags $flags" in content
@@ -729,6 +740,30 @@ def test_write_project_libraries_and_variant(
     assert f"ccache = {_shq('/cc/ccache')}" in content
 
 
+def test_write_project_throw_stubs_reach_core_and_libraries(tmp_path: Path) -> None:
+    """Without exceptions the core and libraries take the throw stubs too."""
+    paths = _make_framework(tmp_path)
+    lib_dir = tmp_path / "libsrc"
+    lib_dir.mkdir()
+    (lib_dir / "lib.cpp").write_text("")
+    library = ArduinoLibrary(
+        name="MyLib",
+        sources=[lib_dir / "lib.cpp"],
+        include_dirs=[lib_dir],
+        flags=["-DMYLIB=1"],
+    )
+    content = _write_ninja(paths, libraries=[library])
+    stubs = CORE.relative_src_path() / THROW_STUBS_HEADER
+    assert f"frameworkflags = -include {_shq(str(stubs))}" in content
+    # Before the library's own flags; core edges take the variable alone
+    assert "  flags = $frameworkflags -DMYLIB=1" in content
+    lines = content.splitlines()
+    core_edge = next(
+        i for i, line in enumerate(lines) if "core_esp8266_main.cpp.o: cxx" in line
+    )
+    assert lines[core_edge + 1] == "  flags = $frameworkflags"
+
+
 def test_get_flash_ld_path(tmp_path: Path) -> None:
 
     paths = InstalledPaths(