Merge pull request #2857 from dtolnay/collide

Revert the colliding aliases hard error (PRs #2562 & #2853)

Author: dtolnay

serde_derive/src/internals/check.rs

@@ -1,8 +1,6 @@
-use crate::internals::ast::{Container, Data, Field, Style, Variant};
+use crate::internals::ast::{Container, Data, Field, Style};
 use crate::internals::attr::{Default, Identifier, TagType};
 use crate::internals::{ungroup, Ctxt, Derive};
-use std::collections::btree_map::Entry;
-use std::collections::{BTreeMap, BTreeSet};
 use syn::{Member, Type};
 
 // Cross-cutting checks that require looking at more than a single attrs object.
@@ -18,7 +16,6 @@ pub fn check(cx: &Ctxt, cont: &mut Container, derive: Derive) {
     check_adjacent_tag_conflict(cx, cont);
     check_transparent(cx, cont, derive);
     check_from_and_try_from(cx, cont);
-    check_name_conflicts(cx, cont, derive);
 }
 
 // If some field of a tuple struct is marked #[serde(default)] then all fields
@@ -478,134 +475,3 @@ fn check_from_and_try_from(cx: &Ctxt, cont: &mut Container) {
         );
     }
 }
-
-// Checks that aliases does not repeated
-fn check_name_conflicts(cx: &Ctxt, cont: &Container, derive: Derive) {
-    if let Derive::Deserialize = derive {
-        match &cont.data {
-            Data::Enum(variants) => check_variant_name_conflicts(cx, variants),
-            Data::Struct(Style::Struct, fields) => check_field_name_conflicts(cx, fields),
-            _ => {}
-        }
-    }
-}
-
-// All renames already applied
-fn check_variant_name_conflicts(cx: &Ctxt, variants: &[Variant]) {
-    let names: BTreeSet<_> = variants
-        .iter()
-        .filter_map(|variant| {
-            if variant.attrs.skip_deserializing() {
-                None
-            } else {
-                Some(variant.attrs.name().deserialize_name().to_owned())
-            }
-        })
-        .collect();
-    let mut alias_owners = BTreeMap::new();
-
-    for variant in variants {
-        let name = variant.attrs.name().deserialize_name();
-
-        for alias in variant.attrs.aliases().intersection(&names) {
-            // Aliases contains variant names, so filter them out
-            if alias == name {
-                continue;
-            }
-
-            // TODO: report other variant location when this become possible
-            cx.error_spanned_by(
-                variant.original,
-                format!(
-                    "alias `{}` conflicts with deserialization name of other variant",
-                    alias
-                ),
-            );
-        }
-
-        for alias in variant.attrs.aliases() {
-            // Aliases contains variant names, so filter them out
-            if alias == name {
-                continue;
-            }
-
-            match alias_owners.entry(alias) {
-                Entry::Vacant(e) => {
-                    e.insert(variant);
-                }
-                Entry::Occupied(e) => {
-                    // TODO: report other variant location when this become possible
-                    cx.error_spanned_by(
-                        variant.original,
-                        format!(
-                            "alias `{}` already used by variant {}",
-                            alias,
-                            e.get().original.ident
-                        ),
-                    );
-                }
-            }
-        }
-
-        check_field_name_conflicts(cx, &variant.fields);
-    }
-}
-
-// All renames already applied
-fn check_field_name_conflicts(cx: &Ctxt, fields: &[Field]) {
-    let names: BTreeSet<_> = fields
-        .iter()
-        .filter_map(|field| {
-            if field.attrs.skip_deserializing() {
-                None
-            } else {
-                Some(field.attrs.name().deserialize_name().to_owned())
-            }
-        })
-        .collect();
-    let mut alias_owners = BTreeMap::new();
-
-    for field in fields {
-        let name = field.attrs.name().deserialize_name();
-
-        for alias in field.attrs.aliases().intersection(&names) {
-            // Aliases contains field names, so filter them out
-            if alias == name {
-                continue;
-            }
-
-            // TODO: report other field location when this become possible
-            cx.error_spanned_by(
-                field.original,
-                format!(
-                    "alias `{}` conflicts with deserialization name of other field",
-                    alias
-                ),
-            );
-        }
-
-        for alias in field.attrs.aliases() {
-            // Aliases contains field names, so filter them out
-            if alias == name {
-                continue;
-            }
-
-            match alias_owners.entry(alias) {
-                Entry::Vacant(e) => {
-                    e.insert(field);
-                }
-                Entry::Occupied(e) => {
-                    // TODO: report other field location when this become possible
-                    cx.error_spanned_by(
-                        field.original,
-                        format!(
-                            "alias `{}` already used by field {}",
-                            alias,
-                            e.get().original.ident.as_ref().unwrap()
-                        ),
-                    );
-                }
-            }
-        }
-    }
-}

test_suite/tests/ui/conflict/alias-enum.rs

@@ -76,4 +76,6 @@ enum E3 {
     b,
 }
 
-fn main() {}
+fn main() {
+    @//fail
+}

test_suite/tests/ui/conflict/alias-enum.stderr

@@ -1,71 +1,79 @@
-error: alias `b` conflicts with deserialization name of other field
-  --> tests/ui/conflict/alias-enum.rs:8:9
+error: expected expression, found `@`
+  --> tests/ui/conflict/alias-enum.rs:80:5
    |
-8  | /         /// Expected error on "alias b", because this is a name of other field
-9  | |         /// Error on "alias a" is not expected because this is a name of this field
-10 | |         /// Error on "alias c" is not expected because field `c` is skipped
-11 | |         #[serde(alias = "a", alias = "b", alias = "c")]
-12 | |         a: (),
-   | |_____________^
+80 |     @//fail
+   |     ^ expected expression
 
-error: alias `c` already used by field a
-  --> tests/ui/conflict/alias-enum.rs:14:9
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:16:9
    |
-14 | /         /// Expected error on "alias c", because it is already used as alias of `a`
-15 | |         #[serde(alias = "c")]
-16 | |         b: (),
-   | |_____________^
+11 |         #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                      --- matches all the relevant values
+...
+16 |         b: (),
+   |         ^ no value can reach this
+   |
+   = note: `#[warn(unreachable_patterns)]` on by default
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:15:25
+   |
+11 |         #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                                   --- matches all the relevant values
+...
+15 |         #[serde(alias = "c")]
+   |                         ^^^ no value can reach this
 
-error: alias `c` conflicts with deserialization name of other field
-  --> tests/ui/conflict/alias-enum.rs:23:9
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:28:26
    |
-23 | /         /// Expected error on "alias c", because this is a name of other field after
-24 | |         /// applying rename rules
-25 | |         #[serde(alias = "b", alias = "c")]
-26 | |         a: (),
-   | |_____________^
+25 |         #[serde(alias = "b", alias = "c")]
+   |                                      --- matches all the relevant values
+...
+28 |         #[serde(rename = "c")]
+   |                          ^^^ no value can reach this
 
-error: alias `B` conflicts with deserialization name of other field
-  --> tests/ui/conflict/alias-enum.rs:34:9
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:38:9
    |
-34 | /         /// Expected error on "alias B", because this is a name of field after
-35 | |         /// applying rename rules
-36 | |         #[serde(alias = "B", alias = "c")]
-37 | |         a: (),
-   | |_____________^
+36 |         #[serde(alias = "B", alias = "c")]
+   |                         --- matches all the relevant values
+37 |         a: (),
+38 |         b: (),
+   |         ^ no value can reach this
 
-error: alias `b` conflicts with deserialization name of other variant
-  --> tests/ui/conflict/alias-enum.rs:44:5
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:52:5
    |
-44 | /     /// Expected error on "alias b", because this is a name of other variant
-45 | |     /// Error on "alias a" is not expected because this is a name of this variant
-46 | |     /// Error on "alias c" is not expected because variant `c` is skipped
-47 | |     #[serde(alias = "a", alias = "b", alias = "c")]
-48 | |     a,
-   | |_____^
+47 |     #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+52 |     b,
+   |     ^ no value can reach this
 
-error: alias `c` already used by variant a
-  --> tests/ui/conflict/alias-enum.rs:50:5
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:51:21
    |
-50 | /     /// Expected error on "alias c", because it is already used as alias of `a`
-51 | |     #[serde(alias = "c")]
-52 | |     b,
-   | |_____^
+47 |     #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                               --- matches all the relevant values
+...
+51 |     #[serde(alias = "c")]
+   |                     ^^^ no value can reach this
 
-error: alias `c` conflicts with deserialization name of other variant
-  --> tests/ui/conflict/alias-enum.rs:60:5
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:65:22
    |
-60 | /     /// Expected error on "alias c", because this is a name of other variant after
-61 | |     /// applying rename rules
-62 | |     #[serde(alias = "b", alias = "c")]
-63 | |     a,
-   | |_____^
+62 |     #[serde(alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+65 |     #[serde(rename = "c")]
+   |                      ^^^ no value can reach this
 
-error: alias `B` conflicts with deserialization name of other variant
-  --> tests/ui/conflict/alias-enum.rs:72:5
+warning: unreachable pattern
+  --> tests/ui/conflict/alias-enum.rs:76:5
    |
-72 | /     /// Expected error on "alias B", because this is a name of variant after
-73 | |     /// applying rename rules
-74 | |     #[serde(alias = "B", alias = "c")]
-75 | |     a,
-   | |_____^
+74 |     #[serde(alias = "B", alias = "c")]
+   |                     --- matches all the relevant values
+75 |     a,
+76 |     b,
+   |     ^ no value can reach this

test_suite/tests/ui/conflict/alias.rs

@@ -37,4 +37,6 @@ struct S3 {
     b: (),
 }
 
-fn main() {}
+fn main() {
+    @//fail
+}

test_suite/tests/ui/conflict/alias.stderr

@@ -1,35 +1,43 @@
-error: alias `b` conflicts with deserialization name of other field
- --> tests/ui/conflict/alias.rs:5:5
-  |
-5 | /     /// Expected error on "alias b", because this is a name of other field
-6 | |     /// Error on "alias a" is not expected because this is a name of this field
-7 | |     /// Error on "alias c" is not expected because field `c` is skipped
-8 | |     #[serde(alias = "a", alias = "b", alias = "c")]
-9 | |     a: (),
-  | |_________^
+error: expected expression, found `@`
+  --> tests/ui/conflict/alias.rs:41:5
+   |
+41 |     @//fail
+   |     ^ expected expression
+
+warning: unreachable pattern
+  --> tests/ui/conflict/alias.rs:13:5
+   |
+8  |     #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+13 |     b: (),
+   |     ^ no value can reach this
+   |
+   = note: `#[warn(unreachable_patterns)]` on by default
 
-error: alias `c` already used by field a
-  --> tests/ui/conflict/alias.rs:11:5
+warning: unreachable pattern
+  --> tests/ui/conflict/alias.rs:12:21
    |
-11 | /     /// Expected error on "alias c", because it is already used as alias of `a`
-12 | |     #[serde(alias = "c")]
-13 | |     b: (),
-   | |_________^
+8  |     #[serde(alias = "a", alias = "b", alias = "c")]
+   |                                               --- matches all the relevant values
+...
+12 |     #[serde(alias = "c")]
+   |                     ^^^ no value can reach this
 
-error: alias `c` conflicts with deserialization name of other field
-  --> tests/ui/conflict/alias.rs:21:5
+warning: unreachable pattern
+  --> tests/ui/conflict/alias.rs:26:22
    |
-21 | /     /// Expected error on "alias c", because this is a name of other field after
-22 | |     /// applying rename rules
-23 | |     #[serde(alias = "b", alias = "c")]
-24 | |     a: (),
-   | |_________^
+23 |     #[serde(alias = "b", alias = "c")]
+   |                                  --- matches all the relevant values
+...
+26 |     #[serde(rename = "c")]
+   |                      ^^^ no value can reach this
 
-error: alias `B` conflicts with deserialization name of other field
-  --> tests/ui/conflict/alias.rs:33:5
+warning: unreachable pattern
+  --> tests/ui/conflict/alias.rs:37:5
    |
-33 | /     /// Expected error on "alias B", because this is a name of field after
-34 | |     /// applying rename rules
-35 | |     #[serde(alias = "B", alias = "c")]
-36 | |     a: (),
-   | |_________^
+35 |     #[serde(alias = "B", alias = "c")]
+   |                     --- matches all the relevant values
+36 |     a: (),
+37 |     b: (),
+   |     ^ no value can reach this