fix(ch32v): honor selected PlatformIO platform and package pins

ci/check_rust_toolchain_pins.py

@@ -100,6 +100,10 @@ def validate_discovered_pins(relative: str, text: str) -> list[str]:
     for line_number, line in enumerate(text.splitlines(), 1):
         versions: set[str] = set()
         for pattern in patterns:
+            if pattern is PIN_FIELD_PATTERNS[1] and Path(relative).suffix not in {".yml", ".yaml"}:
+                # `toolchain:` is also an ordinary Rust struct field; only
+                # workflow YAML declares a Rust toolchain with that spelling.
+                continue
             match = pattern.search(line)
             if match is not None:
                 versions.add(match.group("selector"))

ci/test_rust_toolchain_pins.py

@@ -61,6 +61,14 @@ def test_unrelated_toolchain_package_version_is_not_a_rust_pin(self) -> None:
 
         self.assertEqual(failures, [])
 
+    def test_rust_toolchain_struct_field_is_not_a_workflow_pin(self) -> None:
+        failures = check_rust_toolchain_pins.validate_discovered_pins(
+            "crates/example/src/platform_source.rs",
+            "        toolchain: require_platform_package(&requirements, name),\n",
+        )
+
+        self.assertEqual(failures, [])
+
 
 if __name__ == "__main__":
     unittest.main()

crates/fbuild-build-mcu/src/ch32v/mcu_config.rs

@@ -98,6 +98,17 @@ pub fn normalize_march(march: &str) -> String {
 
 /// Apply board ISA and ABI values to compiler and linker flags.
 pub fn apply_board_isa(config: &mut Ch32vMcuConfig, march: Option<&str>, mabi: Option<&str>) {
+    apply_board_isa_for_toolchain(config, march, mabi, "riscv-none-elf");
+}
+
+/// Preserve WCH's vendor ISA extensions for its own compiler; only the xPack
+/// compiler requires the stripped/modernized `zicsr` spelling.
+pub fn apply_board_isa_for_toolchain(
+    config: &mut Ch32vMcuConfig,
+    march: Option<&str>,
+    mabi: Option<&str>,
+    executable_prefix: &str,
+) {
     fn replace(flags: &mut [String], prefix: &str, value: &str) {
         for flag in flags {
             if flag.starts_with(prefix) {
@@ -107,7 +118,11 @@ pub fn apply_board_isa(config: &mut Ch32vMcuConfig, march: Option<&str>, mabi: O
     }
 
     if let Some(march) = march {
-        let normalized = normalize_march(march);
+        let normalized = if executable_prefix == "riscv-none-elf" {
+            normalize_march(march)
+        } else {
+            march.to_ascii_lowercase()
+        };
         replace(&mut config.compiler_flags.common, "-march=", &normalized);
         replace(&mut config.linker_flags, "-march=", &normalized);
     }
@@ -129,6 +144,30 @@ mod tests {
         assert_eq!(normalize_march("rv32ecxw"), "rv32ec_zicsr");
     }
 
+    #[test]
+    fn platformio_gcc8_preserves_wch_vendor_isa() {
+        let mut config = get_ch32v_config_for_mcu("ch32v003").unwrap();
+        apply_board_isa_for_toolchain(
+            &mut config,
+            Some("rv32ecxw"),
+            Some("ilp32e"),
+            "riscv-none-embed",
+        );
+        assert!(
+            config
+                .compiler_flags
+                .common
+                .contains(&"-march=rv32ecxw".into())
+        );
+        assert!(config.linker_flags.contains(&"-march=rv32ecxw".into()));
+        assert!(
+            !config
+                .compiler_flags
+                .common
+                .contains(&"-march=rv32ec_zicsr".into())
+        );
+    }
+
     #[test]
     fn test_apply_board_isa_updates_compiler_and_linker() {
         let mut config = get_ch32v_config_for_mcu("ch32v003").unwrap();

crates/fbuild-build-mcu/src/ch32v/mod.rs

@@ -1,9 +1,10 @@
-//! CH32V RISC-V platform build support (WCH CH32V003, CH32V203, etc.)
+//! CH32V RISC-V platform build support (WCH CH32V003, CH32V203, etc.)
 
 pub mod ch32v_compiler;
 pub mod ch32v_linker;
 pub mod mcu_config;
 pub mod orchestrator;
+mod platform_source;
 
 pub use ch32v_compiler::Ch32vCompiler;
 pub use ch32v_linker::Ch32vLinker;
@@ -28,8 +29,13 @@ impl crate::PlatformSupport for Ch32vPlatformSupport {
         orchestrator::validate_ch32v_framework(
             inputs.env_config.get("framework").map(String::as_str),
         )?;
-        let (toolchain, cores) =
-            orchestrator::ch32v_packages(inputs.project_dir, Some(inputs.env_config));
+        let (toolchain, cores, _, _) = orchestrator::ch32v_packages(
+            inputs.project_dir,
+            Some(inputs.env_config),
+            &inputs.board.core,
+            mode.fetches(),
+        )
+        .await?;
         Ok(vec![
             provision_package(PackageKind::Toolchain, &toolchain, mode).await,
             provision_package(PackageKind::Framework, &cores, mode).await,