trait selection errors should poison the typeck results, too, so that const eval can avoid running at all

Author: oli-obk

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -273,6 +273,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
         error: &SelectionError<'tcx>,
         fallback_has_occurred: bool,
     ) {
+        self.set_tainted_by_errors();
         let tcx = self.tcx;
         let mut span = obligation.cause.span;
 

src/test/ui/consts/issue-91434.rs

@@ -2,5 +2,4 @@ fn main() {
     [9; [[9E; h]]];
     //~^ ERROR: expected at least one digit in exponent
     //~| ERROR: cannot find value `h` in this scope [E0425]
-    //~| ERROR: constant expression depends on a generic parameter
 }

src/test/ui/consts/issue-91434.stderr

@@ -10,14 +10,6 @@ error[E0425]: cannot find value `h` in this scope
 LL |     [9; [[9E; h]]];
    |               ^ not found in this scope
 
-error: constant expression depends on a generic parameter
-  --> $DIR/issue-91434.rs:2:9
-   |
-LL |     [9; [[9E; h]]];
-   |         ^^^^^^^^^
-   |
-   = note: this may fail depending on what value the parameter takes
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0425`.

src/test/ui/consts/nested_erroneous_ctfe.rs

@@ -0,0 +1,4 @@
+fn main() {
+    [9; || [9; []]];
+    //~^ ERROR: mismatched types
+}

src/test/ui/consts/nested_erroneous_ctfe.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/nested_erroneous_ctfe.rs:2:16
+   |
+LL |     [9; || [9; []]];
+   |                ^^ expected `usize`, found array of 0 elements
+   |
+   = note: expected type `usize`
+             found array `[_; 0]`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.