Resolve regions too when normalizing param env.

Author: nikomatsakis

src/librustc/middle/traits/mod.rs

@@ -18,7 +18,7 @@ pub use self::ObligationCauseCode::*;
 use middle::subst;
 use middle::ty::{self, HasProjectionTypes, Ty};
 use middle::ty_fold::TypeFoldable;
-use middle::infer::{self, InferCtxt};
+use middle::infer::{self, fixup_err_to_string, InferCtxt};
 use std::slice::Iter;
 use std::rc::Rc;
 use syntax::ast;
@@ -395,53 +395,64 @@ pub fn type_known_to_meet_builtin_bound<'a,'tcx>(infcx: &InferCtxt<'a,'tcx>,
     }
 }
 
+/// Normalizes the parameter environment, reporting errors if they occur.
 pub fn normalize_param_env_or_error<'a,'tcx>(unnormalized_env: ty::ParameterEnvironment<'a,'tcx>,
                                              cause: ObligationCause<'tcx>)
                                              -> ty::ParameterEnvironment<'a,'tcx>
 {
-    match normalize_param_env(&unnormalized_env, cause) {
-        Ok(p) => p,
+    // I'm not wild about reporting errors here; I'd prefer to
+    // have the errors get reported at a defined place (e.g.,
+    // during typeck). Instead I have all parameter
+    // environments, in effect, going through this function
+    // and hence potentially reporting errors. This ensurse of
+    // course that we never forget to normalize (the
+    // alternative seemed like it would involve a lot of
+    // manual invocations of this fn -- and then we'd have to
+    // deal with the errors at each of those sites).
+    //
+    // In any case, in practice, typeck constructs all the
+    // parameter environments once for every fn as it goes,
+    // and errors will get reported then; so after typeck we
+    // can be sure that no errors should occur.
+
+    let tcx = unnormalized_env.tcx;
+    let span = cause.span;
+    let body_id = cause.body_id;
+
+    debug!("normalize_param_env_or_error(unnormalized_env={})",
+           unnormalized_env.repr(tcx));
+
+    let infcx = infer::new_infer_ctxt(tcx);
+    let predicates = match fully_normalize(&infcx, &unnormalized_env, cause,
+                                           &unnormalized_env.caller_bounds) {
+        Ok(predicates) => predicates,
         Err(errors) => {
-            // I'm not wild about reporting errors here; I'd prefer to
-            // have the errors get reported at a defined place (e.g.,
-            // during typeck). Instead I have all parameter
-            // environments, in effect, going through this function
-            // and hence potentially reporting errors. This ensurse of
-            // course that we never forget to normalize (the
-            // alternative seemed like it would involve a lot of
-            // manual invocations of this fn -- and then we'd have to
-            // deal with the errors at each of those sites).
-            //
-            // In any case, in practice, typeck constructs all the
-            // parameter environments once for every fn as it goes,
-            // and errors will get reported then; so after typeck we
-            // can be sure that no errors should occur.
-            let infcx = infer::new_infer_ctxt(unnormalized_env.tcx);
             report_fulfillment_errors(&infcx, &errors);
-
-            // Normalized failed? use what they gave us, it's better than nothing.
-            unnormalized_env
+            return unnormalized_env; // an unnormalized env is better than nothing
         }
-    }
-}
-
-pub fn normalize_param_env<'a,'tcx>(param_env: &ty::ParameterEnvironment<'a,'tcx>,
-                                    cause: ObligationCause<'tcx>)
-                                    -> Result<ty::ParameterEnvironment<'a,'tcx>,
-                                              Vec<FulfillmentError<'tcx>>>
-{
-    let tcx = param_env.tcx;
-
-    debug!("normalize_param_env(param_env={})",
-           param_env.repr(tcx));
+    };
 
-    let infcx = infer::new_infer_ctxt(tcx);
-    let predicates = try!(fully_normalize(&infcx, param_env, cause, &param_env.caller_bounds));
+    infcx.resolve_regions_and_report_errors(body_id);
+    let predicates = match infcx.fully_resolve(&predicates) {
+        Ok(predicates) => predicates,
+        Err(fixup_err) => {
+            // If we encounter a fixup error, it means that some type
+            // variable wound up unconstrained. I actually don't know
+            // if this can happen, and I certainly don't expect it to
+            // happen often, but if it did happen it probably
+            // represents a legitimate failure due to some kind of
+            // unconstrained variable, and it seems better not to ICE,
+            // all things considered.
+            let err_msg = fixup_err_to_string(fixup_err);
+            tcx.sess.span_err(span, &err_msg);
+            return unnormalized_env; // an unnormalized env is better than nothing
+        }
+    };
 
-    debug!("normalize_param_env: predicates={}",
+    debug!("normalize_param_env_or_error: predicates={}",
            predicates.repr(tcx));
 
-    Ok(param_env.with_caller_bounds(predicates))
+    unnormalized_env.with_caller_bounds(predicates)
 }
 
 pub fn fully_normalize<'a,'tcx,T>(infcx: &InferCtxt<'a,'tcx>,
@@ -453,8 +464,7 @@ pub fn fully_normalize<'a,'tcx,T>(infcx: &InferCtxt<'a,'tcx>,
 {
     let tcx = closure_typer.tcx();
 
-    debug!("normalize_param_env(value={})",
-           value.repr(tcx));
+    debug!("normalize_param_env(value={})", value.repr(tcx));
 
     let mut selcx = &mut SelectionContext::new(infcx, closure_typer);
     let mut fulfill_cx = FulfillmentContext::new();
@@ -468,8 +478,7 @@ pub fn fully_normalize<'a,'tcx,T>(infcx: &InferCtxt<'a,'tcx>,
     }
     try!(fulfill_cx.select_all_or_error(infcx, closure_typer));
     let resolved_value = infcx.resolve_type_vars_if_possible(&normalized_value);
-    debug!("normalize_param_env: resolved_value={}",
-           resolved_value.repr(tcx));
+    debug!("normalize_param_env: resolved_value={}", resolved_value.repr(tcx));
     Ok(resolved_value)
 }