Expand `tuple-index-suffix` test coverage

Actually, the accidentally accepted invalid suffixes also include tuple
struct indexing positions, struct numeral field name positions. So
before changing anything, first expand test coverage, so we can observe
the effect of bumping the non-lint pseudo-FCW warning into a hard error.

1 files changed, 67 insertions, 8 deletions

diff --git a/tests/ui/parser/tuple-index-suffix.rs b/tests/ui/parser/tuple-index-suffix.rs
index 0fa191d4a7e..31c5bc25063 100644
--- a/tests/ui/parser/tuple-index-suffix.rs
+++ b/tests/ui/parser/tuple-index-suffix.rs
@@ -1,18 +1,77 @@
+//! See #60210.
+//!
+//! Check that we hard error on invalid suffixes in tuple indexing subexpressions and struct numeral
+//! field names, modulo carve-outs for `{i,u}{32,usize}` at warning level to mitigate ecosystem
+//! impact.
+
 struct X(i32,i32,i32);
 
 fn main() {
-    let a = X(1, 2, 3);
-    let b = a.1suffix;
+    let tup_struct = X(1, 2, 3);
+    let invalid_tup_struct_suffix = tup_struct.0suffix;
     //~^ ERROR suffixes on a tuple index are invalid
-    println!("{}", b);
-    let c = (1, 2, 3);
-    let d = c.1suffix;
+    let carve_out_tup_struct_suffix = tup_struct.0i32;
+    //~^ WARN suffixes on a tuple index are invalid
+
+    let tup = (1, 2, 3);
+    let invalid_tup_suffix = tup.0suffix;
     //~^ ERROR suffixes on a tuple index are invalid
-    println!("{}", d);
-    let s = X { 0suffix: 0, 1: 1, 2: 2 };
+    let carve_out_tup_suffix = tup.0u32;
+    //~^ WARN suffixes on a tuple index are invalid
+
+    numeral_struct_field_name_suffix_invalid();
+    numeral_struct_field_name_suffix_carve_out();
+}
+
+// Very limited carve outs as a ecosystem impact mitigation implemented in #60186. *Only*
+// `{i,u}{32,usize}` suffixes are temporarily accepted.
+fn carve_outs() {
+    // Ok, only pseudo-FCW warnings.
+
+    let carve_out_i32 = (42,).0i32;     //~ WARN suffixes on a tuple index are invalid
+    let carve_out_i32 = (42,).0u32;     //~ WARN suffixes on a tuple index are invalid
+    let carve_out_isize = (42,).0isize; //~ WARN suffixes on a tuple index are invalid
+    let carve_out_usize = (42,).0usize; //~ WARN suffixes on a tuple index are invalid
+
+    // Not part of the carve outs!
+    let error_i8 = (42,).0i8;      //~ ERROR suffixes on a tuple index are invalid
+    let error_u8 = (42,).0u8;      //~ ERROR suffixes on a tuple index are invalid
+    let error_i16 = (42,).0i16;    //~ ERROR suffixes on a tuple index are invalid
+    let error_u16 = (42,).0u16;    //~ ERROR suffixes on a tuple index are invalid
+    let error_i64 = (42,).0i64;    //~ ERROR suffixes on a tuple index are invalid
+    let error_u64 = (42,).0u64;    //~ ERROR suffixes on a tuple index are invalid
+    let error_i128 = (42,).0i128;  //~ ERROR suffixes on a tuple index are invalid
+    let error_u128 = (42,).0u128;  //~ ERROR suffixes on a tuple index are invalid
+}
+
+fn numeral_struct_field_name_suffix_invalid() {
+    let invalid_struct_name = X { 0suffix: 0, 1: 1, 2: 2 };
     //~^ ERROR suffixes on a tuple index are invalid
-    match s {
+    match invalid_struct_name {
         X { 0suffix: _, .. } => {}
         //~^ ERROR suffixes on a tuple index are invalid
     }
 }
+
+fn numeral_struct_field_name_suffix_carve_out() {
+    let carve_out_struct_name = X { 0u32: 0, 1: 1, 2: 2 };
+    //~^ WARN suffixes on a tuple index are invalid
+    match carve_out_struct_name {
+        X { 0u32: _, .. } => {}
+        //~^ WARN suffixes on a tuple index are invalid
+    }
+}
+
+// Unfortunately, it turns out `std::mem::offset_of!` uses the same expect suffix code path.
+fn offset_of_suffix() {
+    #[repr(C)]
+    pub struct Struct<T>(u8, T);
+
+    // Carve outs
+    assert_eq!(std::mem::offset_of!(Struct<u32>, 0usize), 0);
+    //~^ WARN suffixes on a tuple index are invalid
+
+    // Not part of carve outs
+    assert_eq!(std::mem::offset_of!(Struct<u32>, 0u8), 0);
+    //~^ ERROR suffixes on a tuple index are invalid
+}