Auto merge of #68434 - varkor:astconv-mismatch-error, r=nikomatsakis

Move generic arg/param validation to `create_substs_for_generic_args` to resolve various const generics issues

This changes some diagnostics, but I think they're around as helpful as the previous ones, and occur infrequently regardless.

Fixes https://github.com/rust-lang/rust/issues/68257.
Fixes https://github.com/rust-lang/rust/issues/68398.

r? @eddyb

1 files changed, 20 insertions, 0 deletions

diff --git a/src/librustc_error_codes/error_codes/E0747.md b/src/librustc_error_codes/error_codes/E0747.md
new file mode 100644
index 00000000000..df1afbfef46
--- /dev/null
+++ b/src/librustc_error_codes/error_codes/E0747.md
@@ -0,0 +1,20 @@
+Generic arguments must be provided in the same order as the corresponding
+generic parameters are declared.
+
+Erroneous code example:
+
+```compile_fail,E0747
+struct S<'a, T>(&'a T);
+
+type X = S<(), 'static>; // error: the type argument is provided before the
+                         // lifetime argument
+```
+
+The argument order should be changed to match the parameter declaration
+order, as in the following.
+
+```
+struct S<'a, T>(&'a T);
+
+type X = S<'static, ()>; // ok
+```