feat(config): Add ChangeId enum for suppressing warnings

Introduces the `ChangeId` enum to allow suppressing `change_id` warnings.
Now, `ChangeId` supports both numeric values and the string literal `"ignore"`.
Numeric values behave as expected, while `"ignore"` is used to suppress warning messages.

Author: Shourya742

src/bootstrap/src/bin/main.rs

@@ -11,8 +11,8 @@ use std::str::FromStr;
 use std::{env, process};
 
 use bootstrap::{
-    Build, CONFIG_CHANGE_HISTORY, Config, Flags, Subcommand, debug, find_recent_config_change_ids,
-    human_readable_changes, t,
+    Build, CONFIG_CHANGE_HISTORY, ChangeId, Config, Flags, Subcommand, debug,
+    find_recent_config_change_ids, human_readable_changes, t,
 };
 #[cfg(feature = "tracing")]
 use tracing::instrument;
@@ -31,7 +31,7 @@ fn main() {
     debug!("parsing flags");
     let flags = Flags::parse(&args);
     debug!("parsing config based on flags");
-    let config = Config::parse(flags);
+    let mut config = Config::parse(flags);
 
     let mut build_lock;
     let _build_lock_guard;
@@ -75,7 +75,7 @@ fn main() {
     {
         None
     } else {
-        check_version(&config)
+        check_version(&mut config)
     };
 
     // NOTE: Since `./configure` generates a `bootstrap.toml`, distro maintainers will see the
@@ -149,14 +149,15 @@ fn main() {
     }
 }
 
-fn check_version(config: &Config) -> Option<String> {
+fn check_version(config: &mut Config) -> Option<String> {
     let mut msg = String::new();
 
     let latest_change_id = CONFIG_CHANGE_HISTORY.last().unwrap().change_id;
     let warned_id_path = config.out.join("bootstrap").join(".last-warned-change-id");
 
-    if let Some(mut id) = config.change_id {
-        if id == latest_change_id {
+    if let Some(ref mut id) = config.change_id {
+        if matches!(id, ChangeId::Id(x) if *x == latest_change_id) || matches!(id, ChangeId::Ignore)
+        {
             return None;
         }
 
@@ -171,11 +172,11 @@ fn check_version(config: &Config) -> Option<String> {
             // Otherwise, we may retrieve all the changes if it's not the highest value.
             // For better understanding, refer to `change_tracker::find_recent_config_change_ids`.
             if CONFIG_CHANGE_HISTORY.iter().any(|config| config.change_id == last_warned_id) {
-                id = last_warned_id;
+                *id = ChangeId::Id(last_warned_id);
             }
         };
 
-        let changes = find_recent_config_change_ids(id);
+        let changes = find_recent_config_change_ids(id.clone());
 
         if changes.is_empty() {
             return None;

src/bootstrap/src/core/config/config.rs

@@ -16,6 +16,7 @@ use std::{cmp, env, fs};
 use build_helper::ci::CiEnv;
 use build_helper::exit;
 use build_helper::git::{GitConfig, get_closest_merge_commit, output_result};
+use serde::de::Visitor;
 use serde::{Deserialize, Deserializer};
 use serde_derive::Deserialize;
 #[cfg(feature = "tracing")]
@@ -183,6 +184,62 @@ pub enum GccCiMode {
     DownloadFromCi,
 }
 
+/// This enum is used for deserializing change IDs from TOML, allowing both numeric values and the string `"ignore"`.
+#[derive(Clone, Debug, PartialEq)]
+pub enum ChangeId {
+    Ignore,
+    Id(usize),
+}
+
+impl<'de> Deserialize<'de> for ChangeId {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct ChangeIdVisitor;
+
+        impl Visitor<'_> for ChangeIdVisitor {
+            type Value = ChangeId;
+
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                formatter.write_str("a usize number or the string \"ignore\"")
+            }
+
+            fn visit_i64<E>(self, value: i64) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                if value >= 0 {
+                    Ok(ChangeId::Id(value as usize))
+                } else {
+                    Err(E::custom(format!(
+                        "invalid negative number `{}`, expected a non-negative usize or \"ignore\"",
+                        value
+                    )))
+                }
+            }
+
+            fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                let value = value.trim();
+                if value.eq_ignore_ascii_case("ignore") {
+                    Ok(ChangeId::Ignore)
+                } else if let Ok(num) = value.parse::<usize>() {
+                    Ok(ChangeId::Id(num))
+                } else {
+                    Err(E::custom(format!(
+                        "invalid value `{}`, expected a usize number or \"ignore\"",
+                        value
+                    )))
+                }
+            }
+        }
+        deserializer.deserialize_any(ChangeIdVisitor)
+    }
+}
+
 /// Global configuration for the entire build and/or bootstrap.
 ///
 /// This structure is parsed from `bootstrap.toml`, and some of the fields are inferred from `git` or build-time parameters.
@@ -193,7 +250,7 @@ pub enum GccCiMode {
 /// `bootstrap.example.toml`.
 #[derive(Default, Clone)]
 pub struct Config {
-    pub change_id: Option<usize>,
+    pub change_id: Option<ChangeId>,
     pub bypass_bootstrap_lock: bool,
     pub ccache: Option<String>,
     /// Call Build::ninja() instead of this.
@@ -707,7 +764,7 @@ pub(crate) struct TomlConfig {
 #[derive(Deserialize, Default)]
 pub(crate) struct ChangeIdWrapper {
     #[serde(alias = "change-id")]
-    pub(crate) inner: Option<usize>,
+    pub(crate) inner: Option<ChangeId>,
 }
 
 /// Describes how to handle conflicts in merging two [`TomlConfig`]

src/bootstrap/src/core/config/tests.rs

@@ -10,6 +10,7 @@ use serde::Deserialize;
 
 use super::flags::Flags;
 use super::{ChangeIdWrapper, Config, RUSTC_IF_UNCHANGED_ALLOWED_PATHS};
+use crate::ChangeId;
 use crate::core::build_steps::clippy::{LintConfig, get_clippy_rules_in_order};
 use crate::core::build_steps::llvm;
 use crate::core::build_steps::llvm::LLVM_INVALIDATION_PATHS;
@@ -171,7 +172,7 @@ runner = "x86_64-runner"
             )
         },
     );
-    assert_eq!(config.change_id, Some(1), "setting top-level value");
+    assert_eq!(config.change_id, Some(ChangeId::Id(1)), "setting top-level value");
     assert_eq!(
         config.rust_lto,
         crate::core::config::RustcLto::Fat,
@@ -311,7 +312,7 @@ fn parse_change_id_with_unknown_field() {
     "#;
 
     let change_id_wrapper: ChangeIdWrapper = toml::from_str(config).unwrap();
-    assert_eq!(change_id_wrapper.inner, Some(3461));
+    assert_eq!(change_id_wrapper.inner, Some(ChangeId::Id(3461)));
 }
 
 #[test]

src/bootstrap/src/lib.rs

@@ -45,8 +45,8 @@ mod core;
 mod utils;
 
 pub use core::builder::PathSet;
-pub use core::config::Config;
 pub use core::config::flags::{Flags, Subcommand};
+pub use core::config::{ChangeId, Config};
 
 #[cfg(feature = "tracing")]
 use tracing::{instrument, span};

src/bootstrap/src/utils/change_tracker.rs

@@ -4,6 +4,8 @@
 
 use std::fmt::Display;
 
+use crate::core::config::ChangeId;
+
 #[cfg(test)]
 mod tests;
 
@@ -35,7 +37,11 @@ impl Display for ChangeSeverity {
     }
 }
 
-pub fn find_recent_config_change_ids(current_id: usize) -> Vec<ChangeInfo> {
+pub fn find_recent_config_change_ids(current_id: ChangeId) -> Vec<ChangeInfo> {
+    let current_id = match current_id {
+        ChangeId::Id(x) => x,
+        ChangeId::Ignore => return Vec::new(),
+    };
     if !CONFIG_CHANGE_HISTORY.iter().any(|config| config.change_id == current_id) {
         // If the current change-id is greater than the most recent one, return
         // an empty list (it may be due to switching from a recent branch to an

src/bootstrap/src/utils/change_tracker/tests.rs

@@ -3,8 +3,11 @@ use crate::{CONFIG_CHANGE_HISTORY, find_recent_config_change_ids};
 #[test]
 fn test_find_recent_config_change_ids() {
     // If change-id is greater than the most recent one, result should be empty.
-    assert!(find_recent_config_change_ids(usize::MAX).is_empty());
+    assert!(find_recent_config_change_ids(crate::ChangeId::Id(usize::MAX)).is_empty());
 
     // There is no change-id equal to or less than 0, result should include the entire change history.
-    assert_eq!(find_recent_config_change_ids(0).len(), CONFIG_CHANGE_HISTORY.len());
+    assert_eq!(
+        find_recent_config_change_ids(crate::ChangeId::Id(0)).len(),
+        CONFIG_CHANGE_HISTORY.len()
+    );
 }