Try avoiding a full clean in cargo sqlx prepare --merged

sqlx-cli/Cargo.toml

@@ -46,6 +46,8 @@ glob = "0.3.0"
 openssl = { version = "0.10.38", optional = true }
 # workaround for https://github.com/rust-lang/rust/issues/29497
 remove_dir_all = "0.7.0"
+cargo_metadata = "0.14"
+filetime = "0.2"
 
 backoff = { version = "0.4.0", features = ["futures", "tokio"] }
 

sqlx-cli/src/lib.rs

@@ -7,6 +7,7 @@ use std::time::Duration;
 use crate::opt::{Command, ConnectOpts, DatabaseCommand, MigrateCommand};
 
 mod database;
+mod metadata;
 // mod migration;
 // mod migrator;
 mod migrate;

sqlx-cli/src/metadata.rs

@@ -0,0 +1,141 @@
+use anyhow::{Context, Result};
+use cargo_metadata::{
+    Metadata as CargoMetadata, Package as MetadataPackage, PackageId as MetadataId,
+};
+
+use std::{
+    collections::{btree_map, BTreeMap, BTreeSet},
+    path::{Path, PathBuf},
+    str::FromStr,
+};
+
+/// The minimal amount of package information we care about
+///
+/// The package's `name` is used to `cargo clean -p` specific crates while the `src_paths` are
+/// are used to trigger recompiles of packages within the workspace
+#[derive(Debug)]
+pub struct Package {
+    name: String,
+    src_paths: Vec<PathBuf>,
+}
+
+impl Package {
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    pub fn src_paths(&self) -> &[PathBuf] {
+        &self.src_paths
+    }
+}
+
+impl From<&MetadataPackage> for Package {
+    fn from(package: &MetadataPackage) -> Self {
+        let name = package.name.clone();
+        let src_paths = package
+            .targets
+            .iter()
+            .map(|target| target.src_path.clone().into_std_path_buf())
+            .collect();
+
+        Self { name, src_paths }
+    }
+}
+
+/// Contains metadata for the current project
+pub struct Metadata {
+    /// Maps packages metadata id to the package
+    ///
+    /// Currently `MetadataId` is used over `PkgId` because pkgid is not a UUID
+    packages: BTreeMap<MetadataId, Package>,
+    /// All of the crates in the current workspace
+    workspace_members: Vec<MetadataId>,
+    /// Maps each dependency to its set of dependents
+    reverse_deps: BTreeMap<MetadataId, BTreeSet<MetadataId>>,
+    /// The target directory of the project
+    ///
+    /// Typically `target` at the workspace root, but can be overridden
+    target_directory: PathBuf,
+}
+
+impl Metadata {
+    pub fn package(&self, id: &MetadataId) -> Option<&Package> {
+        self.packages.get(id)
+    }
+
+    pub fn entries<'this>(&'this self) -> btree_map::Iter<'this, MetadataId, Package> {
+        self.packages.iter()
+    }
+
+    pub fn workspace_members(&self) -> &[MetadataId] {
+        &self.workspace_members
+    }
+
+    pub fn target_directory(&self) -> &Path {
+        &self.target_directory
+    }
+
+    /// Gets all dependents (direct and transitive) of `id`
+    pub fn all_dependents_of(&self, id: &MetadataId) -> BTreeSet<&MetadataId> {
+        let mut dependents = BTreeSet::new();
+        self.all_dependents_of_helper(id, &mut dependents);
+        dependents
+    }
+
+    fn all_dependents_of_helper<'this>(
+        &'this self,
+        id: &MetadataId,
+        dependents: &mut BTreeSet<&'this MetadataId>,
+    ) {
+        if let Some(immediate_dependents) = self.reverse_deps.get(id) {
+            for immediate_dependent in immediate_dependents {
+                if dependents.insert(immediate_dependent) {
+                    self.all_dependents_of_helper(&immediate_dependent, dependents);
+                }
+            }
+        }
+    }
+}
+
+impl FromStr for Metadata {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let CargoMetadata {
+            packages: metadata_packages,
+            workspace_members,
+            resolve,
+            target_directory,
+            ..
+        } = serde_json::from_str(s)?;
+
+        let mut packages = BTreeMap::new();
+        for metadata_package in metadata_packages {
+            let package = Package::from(&metadata_package);
+            packages.insert(metadata_package.id, package);
+        }
+
+        let mut reverse_deps: BTreeMap<_, BTreeSet<_>> = BTreeMap::new();
+        let resolve =
+            resolve.context("Resolving the dependency graph failed (old version of cargo)")?;
+        for node in resolve.nodes {
+            for dep in node.deps {
+                let dependent = node.id.clone();
+                let dependency = dep.pkg;
+                reverse_deps
+                    .entry(dependency)
+                    .or_default()
+                    .insert(dependent);
+            }
+        }
+
+        let target_directory = target_directory.into_std_path_buf();
+
+        Ok(Self {
+            packages,
+            workspace_members,
+            reverse_deps,
+            target_directory,
+        })
+    }
+}