feat: Add action to expand a declarative macro once, inline. Fixes #13598

crates/ide-assists/src/handlers/inline_macro.rs

@@ -0,0 +1,233 @@
+use syntax::ast::{self, AstNode};
+
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: inline_macro
+//
+// Takes a macro and inlines it one step.
+//
+// ```
+// macro_rules! num {
+//     (+$($t:tt)+) => (1 + num!($($t )+));
+//     (-$($t:tt)+) => (-1 + num!($($t )+));
+//     (+) => (1);
+//     (-) => (-1);
+// }
+//
+// fn main() {
+//     let number = num$0!(+ + + - + +);
+//     println!("{number}");
+// }
+// ```
+// ->
+// ```
+// macro_rules! num {
+//     (+$($t:tt)+) => (1 + num!($($t )+));
+//     (-$($t:tt)+) => (-1 + num!($($t )+));
+//     (+) => (1);
+//     (-) => (-1);
+// }
+//
+// fn main() {
+//     let number = 1+num!(+ + - + +);
+//     println!("{number}");
+// }
+// ```
+pub(crate) fn inline_macro(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    let unexpanded = ctx.find_node_at_offset::<ast::MacroCall>()?;
+    let expanded = ctx.sema.expand(&unexpanded)?.clone_for_update();
+
+    let text_range = unexpanded.syntax().text_range();
+
+    acc.add(
+        AssistId("inline_macro", AssistKind::RefactorRewrite),
+        format!("Inline macro"),
+        text_range,
+        |builder| builder.replace(text_range, expanded.to_string()),
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
+
+    macro_rules! simple_macro {
+        () => {
+            r#"
+macro_rules! foo {
+    (foo) => (true);
+    () => (false);
+}
+"#
+        };
+    }
+    macro_rules! double_macro {
+        () => {
+            r#"
+macro_rules! bar {
+    (bar) => (true);
+    ($($tt:tt)?) => (false);
+}
+macro_rules! foo {
+    (foo) => (true);
+    (bar) => (bar!(bar));
+    ($($tt:tt)?) => (bar!($($tt)?));
+}
+"#
+        };
+    }
+
+    macro_rules! complex_macro {
+        () => {
+            r#"
+macro_rules! num {
+    (+$($t:tt)+) => (1 + num!($($t )+));
+    (-$($t:tt)+) => (-1 + num!($($t )+));
+    (+) => (1);
+    (-) => (-1);
+}
+"#
+        };
+    }
+    #[test]
+    fn inline_macro_target() {
+        check_assist_target(
+            inline_macro,
+            concat!(simple_macro!(), r#"fn f() { let a = foo$0!(foo); }"#),
+            "foo!(foo)",
+        );
+    }
+
+    #[test]
+    fn inline_macro_target_start() {
+        check_assist_target(
+            inline_macro,
+            concat!(simple_macro!(), r#"fn f() { let a = $0foo!(foo); }"#),
+            "foo!(foo)",
+        );
+    }
+
+    #[test]
+    fn inline_macro_target_end() {
+        check_assist_target(
+            inline_macro,
+            concat!(simple_macro!(), r#"fn f() { let a = foo!(foo$0); }"#),
+            "foo!(foo)",
+        );
+    }
+
+    #[test]
+    fn inline_macro_simple_case1() {
+        check_assist(
+            inline_macro,
+            concat!(simple_macro!(), r#"fn f() { let result = foo$0!(foo); }"#),
+            concat!(simple_macro!(), r#"fn f() { let result = true; }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_simple_case2() {
+        check_assist(
+            inline_macro,
+            concat!(simple_macro!(), r#"fn f() { let result = foo$0!(); }"#),
+            concat!(simple_macro!(), r#"fn f() { let result = false; }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_simple_not_applicable() {
+        check_assist_not_applicable(
+            inline_macro,
+            concat!(simple_macro!(), r#"fn f() { let result$0 = foo!(foo); }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_simple_not_applicable_broken_macro() {
+        // FIXME: This is a bug. The macro should not expand, but it's
+        // the same behaviour as the "Expand Macro Recursively" commmand
+        // so it's presumably OK for the time being.
+        check_assist(
+            inline_macro,
+            concat!(simple_macro!(), r#"fn f() { let result = foo$0!(asdfasdf); }"#),
+            concat!(simple_macro!(), r#"fn f() { let result = true; }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_double_case1() {
+        check_assist(
+            inline_macro,
+            concat!(double_macro!(), r#"fn f() { let result = foo$0!(bar); }"#),
+            concat!(double_macro!(), r#"fn f() { let result = bar!(bar); }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_double_case2() {
+        check_assist(
+            inline_macro,
+            concat!(double_macro!(), r#"fn f() { let result = foo$0!(asdf); }"#),
+            concat!(double_macro!(), r#"fn f() { let result = bar!(asdf); }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_complex_case1() {
+        check_assist(
+            inline_macro,
+            concat!(complex_macro!(), r#"fn f() { let result = num!(+ +$0 + - +); }"#),
+            concat!(complex_macro!(), r#"fn f() { let result = 1+num!(+ + - +); }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_complex_case2() {
+        check_assist(
+            inline_macro,
+            concat!(complex_macro!(), r#"fn f() { let result = n$0um!(- + + - +); }"#),
+            concat!(complex_macro!(), r#"fn f() { let result = -1+num!(+ + - +); }"#),
+        );
+    }
+
+    #[test]
+    fn inline_macro_recursive_macro() {
+        check_assist(
+            inline_macro,
+            r#"
+macro_rules! foo {
+  () => {foo!()}
+}
+fn f() { let result = foo$0!(); }
+"#,
+            r#"
+macro_rules! foo {
+  () => {foo!()}
+}
+fn f() { let result = foo!(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn inline_macro_unknown_macro() {
+        check_assist_not_applicable(
+            inline_macro,
+            r#"
+fn f() { let result = foo$0!(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn inline_macro_function_call_not_applicable() {
+        check_assist_not_applicable(
+            inline_macro,
+            r#"
+fn f() { let result = foo$0(); }
+"#,
+        );
+    }
+}

crates/ide-assists/src/lib.rs

@@ -159,6 +159,7 @@ mod handlers {
     mod add_return_type;
     mod inline_call;
     mod inline_local_variable;
+    mod inline_macro;
     mod inline_type_alias;
     mod introduce_named_lifetime;
     mod invert_if;
@@ -255,6 +256,7 @@ mod handlers {
             inline_local_variable::inline_local_variable,
             inline_type_alias::inline_type_alias,
             inline_type_alias::inline_type_alias_uses,
+            inline_macro::inline_macro,
             introduce_named_generic::introduce_named_generic,
             introduce_named_lifetime::introduce_named_lifetime,
             invert_if::invert_if,

crates/ide-assists/src/tests/generated.rs

@@ -1438,6 +1438,39 @@ fn main() {
     )
 }
 
+#[test]
+fn doctest_inline_macro() {
+    check_doc_test(
+        "inline_macro",
+        r#####"
+macro_rules! num {
+    (+$($t:tt)+) => (1 + num!($($t )+));
+    (-$($t:tt)+) => (-1 + num!($($t )+));
+    (+) => (1);
+    (-) => (-1);
+}
+
+fn main() {
+    let number = num$0!(+ + + - + +);
+    println!("{number}");
+}
+"#####,
+        r#####"
+macro_rules! num {
+    (+$($t:tt)+) => (1 + num!($($t )+));
+    (-$($t:tt)+) => (-1 + num!($($t )+));
+    (+) => (1);
+    (-) => (-1);
+}
+
+fn main() {
+    let number = 1+num!(+ + - + +);
+    println!("{number}");
+}
+"#####,
+    )
+}
+
 #[test]
 fn doctest_inline_type_alias() {
     check_doc_test(