Add a span to `CompilerBuiltinsCannotCall`

Currently, this error emit a diagnostic with no context like:

    error: `compiler_builtins` cannot call functions through upstream monomorphizations; encountered invalid call from `<math::libm::support::hex_float::Hexf<i32> as core::fmt::LowerHex>::fmt` to `core::fmt::num::<impl core::fmt::LowerHex for i32>::fmt`

With this change, it at least usually points to the problematic
function:

    error: `compiler_builtins` cannot call functions through upstream monomorphizations; encountered invalid call from `<math::libm::support::hex_float::Hexf<i32> as core::fmt::LowerHex>::fmt` to `core::fmt::num::<impl core::fmt::LowerHex for i32>::fmt`
       --> src/../libm/src/math/support/hex_float.rs:270:5
        |
    270 |     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |

3 files changed, 16 insertions, 6 deletions

diff --git a/compiler/rustc_codegen_cranelift/src/abi/mod.rs b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
index 756a2226753..e8076ce77ab 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
@@ -402,9 +402,13 @@ pub(crate) fn codegen_terminator_call<'tcx>(
 
         if is_call_from_compiler_builtins_to_upstream_monomorphization(fx.tcx, instance) {
             if target.is_some() {
-                let caller = with_no_trimmed_paths!(fx.tcx.def_path_str(fx.instance.def_id()));
-                let callee = with_no_trimmed_paths!(fx.tcx.def_path_str(def_id));
-                fx.tcx.dcx().emit_err(CompilerBuiltinsCannotCall { caller, callee });
+                let caller_def = fx.instance.def_id();
+                let e = CompilerBuiltinsCannotCall {
+                    span: fx.tcx.def_span(caller_def),
+                    caller: with_no_trimmed_paths!(fx.tcx.def_path_str(caller_def)),
+                    callee: with_no_trimmed_paths!(fx.tcx.def_path_str(def_id)),
+                };
+                fx.tcx.dcx().emit_err(e);
             } else {
                 fx.bcx.ins().trap(TrapCode::user(2).unwrap());
                 return;
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
index 3ddbe4aeeec..5e25de02a77 100644
--- a/compiler/rustc_codegen_ssa/src/errors.rs
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -1180,6 +1180,8 @@ pub(crate) struct ErrorCreatingRemarkDir {
 pub struct CompilerBuiltinsCannotCall {
     pub caller: String,
     pub callee: String,
+    #[primary_span]
+    pub span: Span,
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 676a241c74b..e351e7352e0 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -165,9 +165,13 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
         if let Some(instance) = instance {
             if is_call_from_compiler_builtins_to_upstream_monomorphization(tcx, instance) {
                 if destination.is_some() {
-                    let caller = with_no_trimmed_paths!(tcx.def_path_str(fx.instance.def_id()));
-                    let callee = with_no_trimmed_paths!(tcx.def_path_str(instance.def_id()));
-                    tcx.dcx().emit_err(CompilerBuiltinsCannotCall { caller, callee });
+                    let caller_def = fx.instance.def_id();
+                    let e = CompilerBuiltinsCannotCall {
+                        span: tcx.def_span(caller_def),
+                        caller: with_no_trimmed_paths!(tcx.def_path_str(caller_def)),
+                        callee: with_no_trimmed_paths!(tcx.def_path_str(instance.def_id())),
+                    };
+                    tcx.dcx().emit_err(e);
                 } else {
                     info!(
                         "compiler_builtins call to diverging function {:?} replaced with abort",