fix(macros): tell the compiler about external files/env vars to watch

closes #663
closes #681

sqlx-macros/src/lib.rs

@@ -2,6 +2,7 @@
     not(any(feature = "postgres", feature = "mysql", feature = "offline")),
     allow(dead_code, unused_macros, unused_imports)
 )]
+#![cfg_attr(procmacro2_semver_exempt, feature(track_path, proc_macro_tracked_env))]
 extern crate proc_macro;
 
 use proc_macro::TokenStream;

sqlx-macros/src/migrate.rs

@@ -24,7 +24,7 @@ struct QuotedMigration {
     version: i64,
     description: String,
     migration_type: QuotedMigrationType,
-    sql: String,
+    path: String,
     checksum: Vec<u8>,
 }
 
@@ -34,7 +34,7 @@ impl ToTokens for QuotedMigration {
             version,
             description,
             migration_type,
-            sql,
+            path,
             checksum,
         } = &self;
 
@@ -43,7 +43,8 @@ impl ToTokens for QuotedMigration {
                 version: #version,
                 description: ::std::borrow::Cow::Borrowed(#description),
                 migration_type:  #migration_type,
-                sql: ::std::borrow::Cow::Borrowed(#sql),
+                // this tells the compiler to watch this path for changes
+                sql: ::std::borrow::Cow::Borrowed(include_str!(#path)),
                 checksum: ::std::borrow::Cow::Borrowed(&[
                     #(#checksum),*
                 ]),
@@ -59,7 +60,7 @@ pub(crate) fn expand_migrator_from_dir(dir: LitStr) -> crate::Result<TokenStream
     let path = crate::common::resolve_path(&dir.value(), dir.span())?;
     let mut migrations = Vec::new();
 
-    for entry in fs::read_dir(path)? {
+    for entry in fs::read_dir(&path)? {
         let entry = entry?;
         if !fs::metadata(entry.path())?.is_file() {
             // not a file; ignore
@@ -89,18 +90,43 @@ pub(crate) fn expand_migrator_from_dir(dir: LitStr) -> crate::Result<TokenStream
 
         let checksum = Vec::from(Sha384::digest(sql.as_bytes()).as_slice());
 
+        // canonicalize the path so we can pass it to `include_str!()`
+        let path = entry.path().canonicalize()?;
+        let path = path
+            .to_str()
+            .ok_or_else(|| {
+                format!(
+                    "migration path cannot be represented as a string: {:?}",
+                    path
+                )
+            })?
+            .to_owned();
+
         migrations.push(QuotedMigration {
             version,
             description,
             migration_type: QuotedMigrationType(migration_type),
-            sql,
+            path,
             checksum,
         })
     }
 
     // ensure that we are sorted by `VERSION ASC`
     migrations.sort_by_key(|m| m.version);
 
+    #[cfg(procmacro2_semver_exempt)]
+    {
+        let path = path.canonicalize()?;
+        let path = path.to_str().ok_or_else(|| {
+            format!(
+                "migration directory path cannot be represented as a string: {:?}",
+                path
+            )
+        })?;
+
+        proc_macro::tracked_path::path(path);
+    }
+
     Ok(quote! {
         ::sqlx::migrate::Migrator {
             migrations: ::std::borrow::Cow::Borrowed(&[

sqlx-macros/src/query/data.rs

@@ -61,16 +61,30 @@ pub mod offline {
         /// Find and deserialize the data table for this query from a shared `sqlx-data.json`
         /// file. The expected structure is a JSON map keyed by the SHA-256 hash of queries in hex.
         pub fn from_data_file(path: impl AsRef<Path>, query: &str) -> crate::Result<Self> {
-            serde_json::Deserializer::from_reader(BufReader::new(
+            let this = serde_json::Deserializer::from_reader(BufReader::new(
                 File::open(path.as_ref()).map_err(|e| {
                     format!("failed to open path {}: {}", path.as_ref().display(), e)
                 })?,
             ))
             .deserialize_map(DataFileVisitor {
                 query,
                 hash: hash_string(query),
-            })
-            .map_err(Into::into)
+            })?;
+
+            #[cfg(procmacr2_semver_exempt)]
+            {
+                let path = path.as_ref().canonicalize()?;
+                let path = path.to_str().ok_or_else(|| {
+                    format!(
+                        "sqlx-data.json path cannot be represented as a string: {:?}",
+                        path
+                    )
+                })?;
+
+                proc_macro::tracked_path::path(path);
+            }
+
+            Ok(this)
         }
     }
 

sqlx-macros/src/query/input.rs

@@ -8,7 +8,7 @@ use syn::{ExprArray, Type};
 
 /// Macro input shared by `query!()` and `query_file!()`
 pub struct QueryMacroInput {
-    pub(super) src: String,
+    pub(super) sql: String,
 
     #[cfg_attr(not(feature = "offline"), allow(dead_code))]
     pub(super) src_span: Span,
@@ -18,6 +18,8 @@ pub struct QueryMacroInput {
     pub(super) arg_exprs: Vec<Expr>,
 
     pub(super) checked: bool,
+
+    pub(super) file_path: Option<String>,
 }
 
 enum QuerySrc {
@@ -94,12 +96,15 @@ impl Parse for QueryMacroInput {
 
         let arg_exprs = args.unwrap_or_default();
 
+        let file_path = src.file_path(src_span)?;
+
         Ok(QueryMacroInput {
-            src: src.resolve(src_span)?,
+            sql: src.resolve(src_span)?,
             src_span,
             record_type,
             arg_exprs,
             checked,
+            file_path,
         })
     }
 }
@@ -112,6 +117,27 @@ impl QuerySrc {
             QuerySrc::File(file) => read_file_src(&file, source_span),
         }
     }
+
+    fn file_path(&self, source_span: Span) -> syn::Result<Option<String>> {
+        if let QuerySrc::File(ref file) = *self {
+            let path = std::path::Path::new(file)
+                .canonicalize()
+                .map_err(|e| syn::Error::new(source_span, e))?;
+
+            Ok(Some(
+                path.to_str()
+                    .ok_or_else(|| {
+                        syn::Error::new(
+                            source_span,
+                            "query file path cannot be represented as a string",
+                        )
+                    })?
+                    .to_string(),
+            ))
+        } else {
+            Ok(None)
+        }
+    }
 }
 
 fn read_file_src(source: &str, source_span: Span) -> syn::Result<String> {

sqlx-macros/src/query/mod.rs

@@ -23,6 +23,7 @@ mod input;
 mod output;
 
 struct Metadata {
+    #[allow(unused)]
     manifest_dir: PathBuf,
     offline: bool,
     database_url: Option<String>,
@@ -35,42 +36,47 @@ struct Metadata {
 // If we are in a workspace, lookup `workspace_root` since `CARGO_MANIFEST_DIR` won't
 // reflect the workspace dir: https://github.com/rust-lang/cargo/issues/3946
 static METADATA: Lazy<Metadata> = Lazy::new(|| {
-    use std::env;
-
-    let manifest_dir: PathBuf = env::var("CARGO_MANIFEST_DIR")
+    let manifest_dir: PathBuf = env("CARGO_MANIFEST_DIR")
         .expect("`CARGO_MANIFEST_DIR` must be set")
         .into();
 
     #[cfg(feature = "offline")]
-    let target_dir =
-        env::var_os("CARGO_TARGET_DIR").map_or_else(|| "target".into(), |dir| dir.into());
+    let target_dir = env("CARGO_TARGET_DIR").map_or_else(|| "target".into(), |dir| dir.into());
 
     // If a .env file exists at CARGO_MANIFEST_DIR, load environment variables from this,
     // otherwise fallback to default dotenv behaviour.
     let env_path = manifest_dir.join(".env");
-    if env_path.exists() {
+
+    #[cfg_attr(not(procmacro2_semver_exempt), allow(unused_variables))]
+    let env_path = if env_path.exists() {
         let res = dotenv::from_path(&env_path);
         if let Err(e) = res {
             panic!("failed to load environment from {:?}, {}", env_path, e);
         }
+
+        Some(env_path)
     } else {
-        let _ = dotenv::dotenv();
+        dotenv::dotenv().ok()
+    };
+
+    // tell the compiler to watch the `.env` for changes, if applicable
+    #[cfg(procmacro2_semver_exempt)]
+    if let Some(env_path) = env_path.as_ref().and_then(|path| path.to_str()) {
+        proc_macro::tracked_path::path(env_path);
     }
 
-    // TODO: Switch to `var_os` after feature(osstring_ascii) is stable.
-    // Stabilization PR: https://github.com/rust-lang/rust/pull/80193
-    let offline = env::var("SQLX_OFFLINE")
+    let offline = env("SQLX_OFFLINE")
         .map(|s| s.eq_ignore_ascii_case("true") || s == "1")
         .unwrap_or(false);
 
-    let database_url = env::var("DATABASE_URL").ok();
+    let database_url = env("DATABASE_URL").ok();
 
     #[cfg(feature = "offline")]
     let workspace_root = {
         use serde::Deserialize;
         use std::process::Command;
 
-        let cargo = env::var_os("CARGO").expect("`CARGO` must be set");
+        let cargo = env("CARGO").expect("`CARGO` must be set");
 
         let output = Command::new(&cargo)
             .args(&["metadata", "--format-version=1"])
@@ -151,7 +157,7 @@ fn expand_from_db(input: QueryMacroInput, db_url: &str) -> crate::Result<TokenSt
         "postgres" | "postgresql" => {
             let data = block_on(async {
                 let mut conn = sqlx_core::postgres::PgConnection::connect(db_url.as_str()).await?;
-                QueryData::from_db(&mut conn, &input.src).await
+                QueryData::from_db(&mut conn, &input.sql).await
             })?;
 
             expand_with_data(input, data, false)
@@ -164,7 +170,7 @@ fn expand_from_db(input: QueryMacroInput, db_url: &str) -> crate::Result<TokenSt
         "mssql" | "sqlserver" => {
             let data = block_on(async {
                 let mut conn = sqlx_core::mssql::MssqlConnection::connect(db_url.as_str()).await?;
-                QueryData::from_db(&mut conn, &input.src).await
+                QueryData::from_db(&mut conn, &input.sql).await
             })?;
 
             expand_with_data(input, data, false)
@@ -177,7 +183,7 @@ fn expand_from_db(input: QueryMacroInput, db_url: &str) -> crate::Result<TokenSt
         "mysql" | "mariadb" => {
             let data = block_on(async {
                 let mut conn = sqlx_core::mysql::MySqlConnection::connect(db_url.as_str()).await?;
-                QueryData::from_db(&mut conn, &input.src).await
+                QueryData::from_db(&mut conn, &input.sql).await
             })?;
 
             expand_with_data(input, data, false)
@@ -190,7 +196,7 @@ fn expand_from_db(input: QueryMacroInput, db_url: &str) -> crate::Result<TokenSt
         "sqlite" => {
             let data = block_on(async {
                 let mut conn = sqlx_core::sqlite::SqliteConnection::connect(db_url.as_str()).await?;
-                QueryData::from_db(&mut conn, &input.src).await
+                QueryData::from_db(&mut conn, &input.sql).await
             })?;
 
             expand_with_data(input, data, false)
@@ -207,7 +213,7 @@ fn expand_from_db(input: QueryMacroInput, db_url: &str) -> crate::Result<TokenSt
 pub fn expand_from_file(input: QueryMacroInput, file: PathBuf) -> crate::Result<TokenStream> {
     use data::offline::DynQueryData;
 
-    let query_data = DynQueryData::from_data_file(file, &input.src)?;
+    let query_data = DynQueryData::from_data_file(file, &input.sql)?;
     assert!(!query_data.db_name.is_empty());
 
     match &*query_data.db_name {
@@ -288,7 +294,7 @@ where
         .all(|it| it.type_info().is_void())
     {
         let db_path = DB::db_path();
-        let sql = &input.src;
+        let sql = &input.sql;
 
         quote! {
             ::sqlx::query_with::<#db_path, _>(#sql, #query_args)
@@ -368,3 +374,16 @@ where
 
     Ok(ret_tokens)
 }
+
+/// Get the value of an environment variable, telling the compiler about it if applicable.
+fn env(name: &str) -> Result<String, std::env::VarError> {
+    #[cfg(procmacro2_semver_exempt)]
+    {
+        proc_macro::tracked_env::var(name)
+    }
+
+    #[cfg(not(procmacro2_semver_exempt))]
+    {
+        std::env::var(name)
+    }
+}

sqlx-macros/src/query/output.rs

@@ -157,7 +157,14 @@ pub fn quote_query_as<DB: DatabaseExt>(
 
     let db_path = DB::db_path();
     let row_path = DB::row_path();
-    let sql = &input.src;
+
+    // if this query came from a file, use `include_str!()` to tell the compiler where it came from
+    let sql = if let Some(ref path) = &input.file_path {
+        quote::quote_spanned! { input.src_span => include_str!(#path) }
+    } else {
+        let sql = &input.sql;
+        quote! { #sql }
+    };
 
     quote! {
         ::sqlx::query_with::<#db_path, _>(#sql, #bind_args).try_map(|row: #row_path| {
@@ -200,7 +207,7 @@ pub fn quote_query_scalar<DB: DatabaseExt>(
     };
 
     let db = DB::db_path();
-    let query = &input.src;
+    let query = &input.sql;
 
     Ok(quote! {
         ::sqlx::query_scalar_with::<#db, #ty, _>(#query, #bind_args)