Auto merge of rust-lang#13458 - cameron1024:suggest-checked-wrapping-saturating, r=Veykril

add wrapping/checked/saturating assist

This addresses rust-lang#13452

I'm not sure about the structure of the code. I'm not sure if it needs to be 3 separate assists, and if that means it needs to be in 3 separate files as well.

Most of the logic is in `util.rs`, which feels funny to me, but there seems to be a pattern of 1 assist per file, and this seems better than duplicating the logic.

Let me know if anything needs changes 😁

Author: bors

crates/hir/src/lib.rs

@@ -2926,6 +2926,13 @@ impl Type {
         matches!(self.ty.kind(Interner), TyKind::Scalar(Scalar::Uint(UintTy::Usize)))
     }
 
+    pub fn is_int_or_uint(&self) -> bool {
+        match self.ty.kind(Interner) {
+            TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_)) => true,
+            _ => false,
+        }
+    }
+
     pub fn remove_ref(&self) -> Option<Type> {
         match &self.ty.kind(Interner) {
             TyKind::Ref(.., ty) => Some(self.derived(ty.clone())),

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

@@ -0,0 +1,226 @@
+use ide_db::assists::{AssistId, AssistKind, GroupLabel};
+use syntax::{
+    ast::{self, ArithOp, BinaryOp},
+    AstNode, TextRange,
+};
+
+use crate::assist_context::{AssistContext, Assists};
+
+// Assist: replace_arith_with_checked
+//
+// Replaces arithmetic on integers with the `checked_*` equivalent.
+//
+// ```
+// fn main() {
+//   let x = 1 $0+ 2;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//   let x = 1.checked_add(2);
+// }
+// ```
+pub(crate) fn replace_arith_with_checked(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    replace_arith(acc, ctx, ArithKind::Checked)
+}
+
+// Assist: replace_arith_with_saturating
+//
+// Replaces arithmetic on integers with the `saturating_*` equivalent.
+//
+// ```
+// fn main() {
+//   let x = 1 $0+ 2;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//   let x = 1.saturating_add(2);
+// }
+// ```
+pub(crate) fn replace_arith_with_saturating(
+    acc: &mut Assists,
+    ctx: &AssistContext<'_>,
+) -> Option<()> {
+    replace_arith(acc, ctx, ArithKind::Saturating)
+}
+
+// Assist: replace_arith_with_wrapping
+//
+// Replaces arithmetic on integers with the `wrapping_*` equivalent.
+//
+// ```
+// fn main() {
+//   let x = 1 $0+ 2;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//   let x = 1.wrapping_add(2);
+// }
+// ```
+pub(crate) fn replace_arith_with_wrapping(
+    acc: &mut Assists,
+    ctx: &AssistContext<'_>,
+) -> Option<()> {
+    replace_arith(acc, ctx, ArithKind::Wrapping)
+}
+
+fn replace_arith(acc: &mut Assists, ctx: &AssistContext<'_>, kind: ArithKind) -> Option<()> {
+    let (lhs, op, rhs) = parse_binary_op(ctx)?;
+
+    if !is_primitive_int(ctx, &lhs) || !is_primitive_int(ctx, &rhs) {
+        return None;
+    }
+
+    let start = lhs.syntax().text_range().start();
+    let end = rhs.syntax().text_range().end();
+    let range = TextRange::new(start, end);
+
+    acc.add_group(
+        &GroupLabel("replace_arith".into()),
+        kind.assist_id(),
+        kind.label(),
+        range,
+        |builder| {
+            let method_name = kind.method_name(op);
+
+            builder.replace(range, format!("{lhs}.{method_name}({rhs})"))
+        },
+    )
+}
+
+fn is_primitive_int(ctx: &AssistContext<'_>, expr: &ast::Expr) -> bool {
+    match ctx.sema.type_of_expr(expr) {
+        Some(ty) => ty.adjusted().is_int_or_uint(),
+        _ => false,
+    }
+}
+
+/// Extract the operands of an arithmetic expression (e.g. `1 + 2` or `1.checked_add(2)`)
+fn parse_binary_op(ctx: &AssistContext<'_>) -> Option<(ast::Expr, ArithOp, ast::Expr)> {
+    let expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
+
+    let op = match expr.op_kind() {
+        Some(BinaryOp::ArithOp(ArithOp::Add)) => ArithOp::Add,
+        Some(BinaryOp::ArithOp(ArithOp::Sub)) => ArithOp::Sub,
+        Some(BinaryOp::ArithOp(ArithOp::Mul)) => ArithOp::Mul,
+        Some(BinaryOp::ArithOp(ArithOp::Div)) => ArithOp::Div,
+        _ => return None,
+    };
+
+    let lhs = expr.lhs()?;
+    let rhs = expr.rhs()?;
+
+    Some((lhs, op, rhs))
+}
+
+pub(crate) enum ArithKind {
+    Saturating,
+    Wrapping,
+    Checked,
+}
+
+impl ArithKind {
+    fn assist_id(&self) -> AssistId {
+        let s = match self {
+            ArithKind::Saturating => "replace_arith_with_saturating",
+            ArithKind::Checked => "replace_arith_with_checked",
+            ArithKind::Wrapping => "replace_arith_with_wrapping",
+        };
+
+        AssistId(s, AssistKind::RefactorRewrite)
+    }
+
+    fn label(&self) -> &'static str {
+        match self {
+            ArithKind::Saturating => "Replace arithmetic with call to saturating_*",
+            ArithKind::Checked => "Replace arithmetic with call to checked_*",
+            ArithKind::Wrapping => "Replace arithmetic with call to wrapping_*",
+        }
+    }
+
+    fn method_name(&self, op: ArithOp) -> String {
+        let prefix = match self {
+            ArithKind::Checked => "checked_",
+            ArithKind::Wrapping => "wrapping_",
+            ArithKind::Saturating => "saturating_",
+        };
+
+        let suffix = match op {
+            ArithOp::Add => "add",
+            ArithOp::Sub => "sub",
+            ArithOp::Mul => "mul",
+            ArithOp::Div => "div",
+            _ => unreachable!("this function should only be called with +, -, / or *"),
+        };
+        format!("{prefix}{suffix}")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::check_assist;
+
+    use super::*;
+
+    #[test]
+    fn arith_kind_method_name() {
+        assert_eq!(ArithKind::Saturating.method_name(ArithOp::Add), "saturating_add");
+        assert_eq!(ArithKind::Checked.method_name(ArithOp::Sub), "checked_sub");
+    }
+
+    #[test]
+    fn replace_arith_with_checked_add() {
+        check_assist(
+            replace_arith_with_checked,
+            r#"
+fn main() {
+    let x = 1 $0+ 2;
+}
+"#,
+            r#"
+fn main() {
+    let x = 1.checked_add(2);
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn replace_arith_with_saturating_add() {
+        check_assist(
+            replace_arith_with_saturating,
+            r#"
+fn main() {
+    let x = 1 $0+ 2;
+}
+"#,
+            r#"
+fn main() {
+    let x = 1.saturating_add(2);
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn replace_arith_with_wrapping_add() {
+        check_assist(
+            replace_arith_with_wrapping,
+            r#"
+fn main() {
+    let x = 1 $0+ 2;
+}
+"#,
+            r#"
+fn main() {
+    let x = 1.wrapping_add(2);
+}
+"#,
+        )
+    }
+}

crates/ide-assists/src/lib.rs

@@ -186,6 +186,7 @@ mod handlers {
     mod replace_derive_with_manual_impl;
     mod replace_if_let_with_match;
     mod replace_or_with_or_else;
+    mod replace_arith_op;
     mod introduce_named_generic;
     mod replace_let_with_if_let;
     mod replace_qualified_name_with_use;
@@ -293,6 +294,9 @@ mod handlers {
             replace_or_with_or_else::replace_or_with_or_else,
             replace_turbofish_with_explicit_type::replace_turbofish_with_explicit_type,
             replace_qualified_name_with_use::replace_qualified_name_with_use,
+            replace_arith_op::replace_arith_with_wrapping,
+            replace_arith_op::replace_arith_with_checked,
+            replace_arith_op::replace_arith_with_saturating,
             sort_items::sort_items,
             split_import::split_import,
             toggle_ignore::toggle_ignore,

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

@@ -2066,6 +2066,57 @@ impl Foo for Bar {
     )
 }
 
+#[test]
+fn doctest_replace_arith_with_checked() {
+    check_doc_test(
+        "replace_arith_with_checked",
+        r#####"
+fn main() {
+  let x = 1 $0+ 2;
+}
+"#####,
+        r#####"
+fn main() {
+  let x = 1.checked_add(2);
+}
+"#####,
+    )
+}
+
+#[test]
+fn doctest_replace_arith_with_saturating() {
+    check_doc_test(
+        "replace_arith_with_saturating",
+        r#####"
+fn main() {
+  let x = 1 $0+ 2;
+}
+"#####,
+        r#####"
+fn main() {
+  let x = 1.saturating_add(2);
+}
+"#####,
+    )
+}
+
+#[test]
+fn doctest_replace_arith_with_wrapping() {
+    check_doc_test(
+        "replace_arith_with_wrapping",
+        r#####"
+fn main() {
+  let x = 1 $0+ 2;
+}
+"#####,
+        r#####"
+fn main() {
+  let x = 1.wrapping_add(2);
+}
+"#####,
+    )
+}
+
 #[test]
 fn doctest_replace_char_with_string() {
     check_doc_test(