Tighter spans

compiler/rustc_passes/src/check_attr.rs

@@ -20,7 +20,7 @@ use rustc_hir::{MethodKind, Target, Unsafety};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
 use rustc_middle::traits::ObligationCause;
-use rustc_middle::ty::error::ExpectedFound;
+use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::lint::builtin::{
@@ -2213,7 +2213,7 @@ impl CheckAttrVisitor<'_> {
             tcx.fn_sig(def_id).subst(tcx, fresh_substs),
         );
 
-        let cause = ObligationCause::misc(span, def_id);
+        let mut cause = ObligationCause::misc(span, def_id);
         let sig = ocx.normalize(&cause, param_env, sig);
 
         // proc macro is not WF.
@@ -2235,6 +2235,39 @@ impl CheckAttrVisitor<'_> {
 
         if let Err(terr) = ocx.eq(&cause, param_env, expected_sig, sig) {
             let mut diag = tcx.sess.create_err(errors::ProcMacroBadSig { span, kind });
+
+            let hir_sig = tcx.hir().fn_sig_by_hir_id(hir_id);
+            if let Some(hir_sig) = hir_sig {
+                match terr {
+                    TypeError::ArgumentMutability(idx) | TypeError::ArgumentSorts(_, idx) => {
+                        if let Some(ty) = hir_sig.decl.inputs.get(idx) {
+                            diag.set_span(ty.span);
+                            cause.span = ty.span;
+                        } else if idx == hir_sig.decl.inputs.len() {
+                            let span = hir_sig.decl.output.span();
+                            diag.set_span(span);
+                            cause.span = span;
+                        }
+                    }
+                    TypeError::ArgCount => {
+                        if let Some(ty) = hir_sig.decl.inputs.get(expected_sig.inputs().len()) {
+                            diag.set_span(ty.span);
+                            cause.span = ty.span;
+                        }
+                    }
+                    TypeError::UnsafetyMismatch(_) => {
+                        // FIXME: Would be nice if we had a span here..
+                    }
+                    TypeError::AbiMismatch(_) => {
+                        // FIXME: Would be nice if we had a span here..
+                    }
+                    TypeError::VariadicMismatch(_) => {
+                        // FIXME: Would be nice if we had a span here..
+                    }
+                    _ => {}
+                }
+            }
+
             infcx.err_ctxt().note_type_err(
                 &mut diag,
                 &cause,

tests/ui/proc-macro/signature-proc-macro-attribute.stderr

@@ -26,10 +26,10 @@ LL | pub fn bad_everything(input: String) -> String {
               found signature `fn(std::string::String) -> std::string::String`
 
 error: attribute proc macro has incorrect signature
-  --> $DIR/signature-proc-macro-attribute.rs:28:1
+  --> $DIR/signature-proc-macro-attribute.rs:28:52
    |
 LL | pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ incorrect number of function parameters
+   |                                                    ^^^^^^ incorrect number of function parameters
    |
    = note: expected signature `fn(proc_macro::TokenStream, proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(proc_macro::TokenStream, proc_macro::TokenStream, std::string::String) -> proc_macro::TokenStream`

tests/ui/proc-macro/signature-proc-macro-derive.stderr

@@ -1,35 +1,35 @@
 error: derive proc macro has incorrect signature
-  --> $DIR/signature-proc-macro-derive.rs:10:1
+  --> $DIR/signature-proc-macro-derive.rs:10:25
    |
 LL | pub fn bad_input(input: String) -> TokenStream {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
+   |                         ^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(std::string::String) -> proc_macro::TokenStream`
 
 error: derive proc macro has incorrect signature
-  --> $DIR/signature-proc-macro-derive.rs:16:1
+  --> $DIR/signature-proc-macro-derive.rs:16:42
    |
 LL | pub fn bad_output(input: TokenStream) -> String {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
+   |                                          ^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(proc_macro::TokenStream) -> std::string::String`
 
 error: derive proc macro has incorrect signature
-  --> $DIR/signature-proc-macro-derive.rs:22:1
+  --> $DIR/signature-proc-macro-derive.rs:22:30
    |
 LL | pub fn bad_everything(input: String) -> String {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
+   |                              ^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(std::string::String) -> std::string::String`
 
 error: derive proc macro has incorrect signature
-  --> $DIR/signature-proc-macro-derive.rs:28:1
+  --> $DIR/signature-proc-macro-derive.rs:28:36
    |
 LL | pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ incorrect number of function parameters
+   |                                    ^^^^^^^^^^^ incorrect number of function parameters
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(proc_macro::TokenStream, proc_macro::TokenStream, std::string::String) -> proc_macro::TokenStream`

tests/ui/proc-macro/signature-proc-macro.stderr

@@ -1,35 +1,35 @@
 error: function-like proc macro has incorrect signature
-  --> $DIR/signature-proc-macro.rs:10:1
+  --> $DIR/signature-proc-macro.rs:10:25
    |
 LL | pub fn bad_input(input: String) -> TokenStream {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
+   |                         ^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(std::string::String) -> proc_macro::TokenStream`
 
 error: function-like proc macro has incorrect signature
-  --> $DIR/signature-proc-macro.rs:16:1
+  --> $DIR/signature-proc-macro.rs:16:42
    |
 LL | pub fn bad_output(input: TokenStream) -> String {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
+   |                                          ^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(proc_macro::TokenStream) -> std::string::String`
 
 error: function-like proc macro has incorrect signature
-  --> $DIR/signature-proc-macro.rs:22:1
+  --> $DIR/signature-proc-macro.rs:22:30
    |
 LL | pub fn bad_everything(input: String) -> String {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
+   |                              ^^^^^^ expected `proc_macro::TokenStream`, found `std::string::String`
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(std::string::String) -> std::string::String`
 
 error: function-like proc macro has incorrect signature
-  --> $DIR/signature-proc-macro.rs:28:1
+  --> $DIR/signature-proc-macro.rs:28:36
    |
 LL | pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ incorrect number of function parameters
+   |                                    ^^^^^^^^^^^ incorrect number of function parameters
    |
    = note: expected signature `fn(proc_macro::TokenStream) -> proc_macro::TokenStream`
               found signature `fn(proc_macro::TokenStream, proc_macro::TokenStream, std::string::String) -> proc_macro::TokenStream`