Rollup merge of #84913 - estebank:issue-84831, r=varkor

Do not ICE on invalid const param

When encountering a path that can't have generics, do not call
`generics_of`. This would happen when writing something like
`path::this_is_a_mod<const_val>`.

Fix #84831.

src/test/ui/typeck/issue-84831.rs

@@ -0,0 +1,9 @@
+fn f() {
+    std::<0>; //~ ERROR expected value
+}
+fn j() {
+    std::<_ as _>; //~ ERROR expected value
+    //~^ ERROR expected one of `,` or `>`, found keyword `as`
+}
+
+fn main () {}

src/test/ui/typeck/issue-84831.stderr

@@ -0,0 +1,26 @@
+error: expected one of `,` or `>`, found keyword `as`
+  --> $DIR/issue-84831.rs:5:13
+   |
+LL |     std::<_ as _>;
+   |             ^^ expected one of `,` or `>`
+   |
+help: expressions must be enclosed in braces to be used as const generic arguments
+   |
+LL |     std::<{ _ as _ }>;
+   |           ^        ^
+
+error[E0423]: expected value, found crate `std`
+  --> $DIR/issue-84831.rs:2:5
+   |
+LL |     std::<0>;
+   |     ^^^^^^^^ not a value
+
+error[E0423]: expected value, found crate `std`
+  --> $DIR/issue-84831.rs:5:5
+   |
+LL |     std::<_ as _>;
+   |     ^^^^^^^^^^^^^ not a value
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0423`.