Sidestep warning about repeated E0045 span_err! invocation.

(That is, take the two expressions with the same message and unify
them into one subroutine.)

Author: pnkfelix

src/librustc_typeck/astconv.rs

@@ -58,6 +58,7 @@ use middle::subst::{FnSpace, TypeSpace, SelfSpace, Subst, Substs};
 use middle::traits;
 use middle::ty::{self, RegionEscape, Ty, ToPredicate, HasTypeFlags};
 use middle::ty_fold;
+use require_c_abi_if_variadic;
 use rscope::{self, UnelidableRscope, RegionScope, ElidableRscope, ExplicitRscope,
              ObjectLifetimeDefaultRscope, ShiftedRscope, BindingRscope,
              ElisionFailureInfo, ElidedLifetime};
@@ -1574,10 +1575,7 @@ pub fn ast_ty_to_ty<'tcx>(this: &AstConv<'tcx>,
         }
         ast::TyParen(ref typ) => ast_ty_to_ty(this, rscope, &**typ),
         ast::TyBareFn(ref bf) => {
-            if bf.decl.variadic && bf.abi != abi::C {
-                span_err!(tcx.sess, ast_ty.span, E0045,
-                          "variadic function must have C calling convention");
-            }
+            require_c_abi_if_variadic(tcx, &bf.decl, bf.abi, ast_ty.span);
             let bare_fn = ty_of_bare_fn(this, bf.unsafety, bf.abi, &*bf.decl);
             tcx.mk_fn(None, tcx.mk_bare_fn(bare_fn))
         }

src/librustc_typeck/check/mod.rs

@@ -97,6 +97,7 @@ use middle::ty::{Disr, ParamTy, ParameterEnvironment};
 use middle::ty::{self, HasTypeFlags, RegionEscape, ToPolyTraitRef, Ty};
 use middle::ty::{MethodCall, MethodCallee};
 use middle::ty_fold::{TypeFolder, TypeFoldable};
+use require_c_abi_if_variadic;
 use rscope::{ElisionFailureInfo, RegionScope};
 use session::Session;
 use {CrateCtxt, lookup_full_def, require_same_types};
@@ -685,10 +686,7 @@ pub fn check_item_type<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>, it: &'tcx ast::Item) {
                 }
 
                 if let ast::ForeignItemFn(ref fn_decl, _) = item.node {
-                    if fn_decl.variadic && m.abi != abi::C {
-                        span_err!(ccx.tcx.sess, item.span, E0045,
-                                  "variadic function must have C calling convention");
-                    }
+                    require_c_abi_if_variadic(ccx.tcx, fn_decl, m.abi, item.span);
                 }
             }
         }

src/librustc_typeck/lib.rs

@@ -176,6 +176,16 @@ fn lookup_full_def(tcx: &ty::ctxt, sp: Span, id: ast::NodeId) -> def::Def {
     }
 }
 
+fn require_c_abi_if_variadic(tcx: &ty::ctxt,
+                             decl: &ast::FnDecl,
+                             abi: abi::Abi,
+                             span: Span) {
+    if decl.variadic && abi != abi::C {
+        span_err!(tcx.sess, span, E0045,
+                  "variadic function must have C calling convention");
+    }
+}
+
 fn require_same_types<'a, 'tcx, M>(tcx: &ty::ctxt<'tcx>,
                                    maybe_infcx: Option<&infer::InferCtxt<'a, 'tcx>>,
                                    t1_is_expected: bool,