Update E0453 to new error format

Fixes rust-lang#35929.
Part of rust-lang#35233.

r? @jonathandturner

Author: 0xmohit

src/librustc/lint/context.rs

@@ -606,11 +606,12 @@ pub trait LintContext: Sized {
                                                             "{}({}) overruled by outer forbid({})",
                                                             level.as_str(), lint_name,
                                                             lint_name);
+                    diag_builder.span_label(span, &format!("overruled by previous forbid"));
                     match now_source {
                         LintSource::Default => &mut diag_builder,
                         LintSource::Node(forbid_source_span) => {
-                            diag_builder.span_note(forbid_source_span,
-                                                   "`forbid` lint level set here")
+                            diag_builder.span_label(forbid_source_span,
+                                                    &format!("`forbid` level set here"))
                         },
                         LintSource::CommandLine => {
                             diag_builder.note("`forbid` lint level was set on command line")

src/test/compile-fail-fulldeps/lint-plugin-forbid-attrs.rs

@@ -15,11 +15,13 @@
 #![plugin(lint_plugin_test)]
 #![forbid(test_lint)]
 //~^ NOTE lint level defined here
-//~| NOTE `forbid` lint level set here
+//~| NOTE `forbid` level set here
 
 fn lintme() { } //~ ERROR item is named 'lintme'
 
-#[allow(test_lint)] //~ ERROR allow(test_lint) overruled by outer forbid(test_lint)
+#[allow(test_lint)]
+//~^ ERROR allow(test_lint) overruled by outer forbid(test_lint)
+//~| NOTE overruled by previous forbid
 pub fn main() {
     lintme();
 }

src/test/compile-fail/E0453.rs

@@ -9,7 +9,10 @@
 // except according to those terms.
 
 #![forbid(non_snake_case)]
+//~^ NOTE `forbid` level set here
 
-#[allow(non_snake_case)] //~ ERROR E0453
+#[allow(non_snake_case)]
+//~^ ERROR allow(non_snake_case) overruled by outer forbid(non_snake_case)
+//~| NOTE overruled by previous forbid
 fn main() {
 }

src/test/compile-fail/lint-forbid-attr.rs

@@ -9,8 +9,10 @@
 // except according to those terms.
 
 #![forbid(deprecated)]
-//~^ NOTE `forbid` lint level set here
+//~^ NOTE `forbid` level set here
 
-#[allow(deprecated)] //~ ERROR allow(deprecated) overruled by outer forbid(deprecated)
+#[allow(deprecated)]
+//~^ ERROR allow(deprecated) overruled by outer forbid(deprecated)
+//~| NOTE overruled by previous forbid
 fn main() {
 }