Merge #6965

6965: Properly attach attributes to Param instead of parent ParamList r=matklad a=Veykril

Fixes #2783, fixes #2781

The problem with `let _a = [0,#[cfg(feature = "L")]0];` has already been fixed some time ago it seems:
<details>
  <summary>Syntax Tree for the const item</summary>

```
  [email protected]
    [email protected] "let"
    [email protected] " "
    [email protected]
      [email protected]
        [email protected] "_a"
    [email protected] " "
    [email protected] "="
    [email protected] " "
    [email protected]
      [email protected] "["
      [email protected]
        [email protected] "0"
      [email protected] ","
      [email protected]
        [email protected]
          [email protected] "#"
          [email protected] "["
          [email protected]
            [email protected]
              [email protected]
                [email protected] "cfg"
          [email protected]
            [email protected] "("
            [email protected] "feature"
            [email protected] " "
            [email protected] "="
            [email protected] " "
            [email protected] "\"L\""
            [email protected] ")"
          [email protected] "]"
        [email protected] "0"
      [email protected] "]"
    [email protected] ";"
```
</details>

Co-authored-by: Lukas Wirth <[email protected]>

3 files changed, 61 insertions, 10 deletions

diff --git a/crates/syntax/test_data/parser/inline/ok/0138_self_param_outer_attr.rast b/crates/syntax/test_data/parser/inline/ok/0138_self_param_outer_attr.rast
index 6403ff8d5..d3219f0b2 100644
--- a/crates/syntax/test_data/parser/inline/ok/0138_self_param_outer_attr.rast
+++ b/crates/syntax/test_data/parser/inline/ok/0138_self_param_outer_attr.rast
@@ -6,16 +6,16 @@ [email protected]
       [email protected] "f"
     [email protected]
       [email protected] "("
-      ATT[email protected]6
-        POUND@5..6 "#"
-        L_BRACK@6..7 "["
-        PATH@7..15
-          PATH_SEGMENT@7..15
-            NAME_REF@7..15
-              IDENT@7..15 "must_use"
-        R_BRACK@15..16 "]"
-      WHITESPACE@16..17 " "
-      SELF_PARAM@17..21
+      SELF_PARAM@5..21
+        ATTR@5..16
+          POUND@5..6 "#"
+          L_BRACK@6..7 "["
+          [email protected]
+            PATH_SEGMENT@7..15
+              NAME_REF@7..15
+                IDENT@7..15 "must_use"
+          R_BRACK@15..16 "]"
+        WHITESPACE@16..17 " "
         [email protected] "self"
       [email protected] ")"
     [email protected] " "
diff --git a/crates/syntax/test_data/parser/inline/ok/0154_tuple_attrs.rast b/crates/syntax/test_data/parser/inline/ok/0154_tuple_attrs.rast
new file mode 100644
index 000000000..d34b21abe
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0154_tuple_attrs.rast
@@ -0,0 +1,50 @@
+[email protected]
+  [email protected]
+    [email protected] "const"
+    [email protected] " "
+    [email protected]
+      [email protected] "A"
+    [email protected] ":"
+    [email protected] " "
+    [email protected]
+      [email protected] "("
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected] "i64"
+      [email protected] ","
+      [email protected] " "
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected] "i64"
+      [email protected] ")"
+    [email protected] " "
+    [email protected] "="
+    [email protected] " "
+    [email protected]
+      [email protected] "("
+      [email protected]
+        [email protected] "1"
+      [email protected] ","
+      [email protected] " "
+      [email protected]
+        [email protected]
+          [email protected] "#"
+          [email protected] "["
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected] "cfg"
+          [email protected]
+            [email protected] "("
+            [email protected] "test"
+            [email protected] ")"
+          [email protected] "]"
+        [email protected] " "
+        [email protected] "2"
+      [email protected] ")"
+    [email protected] ";"
+  [email protected] "\n"
diff --git a/crates/syntax/test_data/parser/inline/ok/0154_tuple_attrs.rs b/crates/syntax/test_data/parser/inline/ok/0154_tuple_attrs.rs
new file mode 100644
index 000000000..f84b7ab31
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0154_tuple_attrs.rs
@@ -0,0 +1 @@
+const A: (i64, i64) = (1, #[cfg(test)] 2);