Create `core::fmt::ArgumentV1` with generics instead of fn pointer

12 files changed, 98 insertions, 72 deletions

diff --git a/compiler/rustc_builtin_macros/src/format.rs b/compiler/rustc_builtin_macros/src/format.rs
index d1393528d1c..453f2163da1 100644
--- a/compiler/rustc_builtin_macros/src/format.rs
+++ b/compiler/rustc_builtin_macros/src/format.rs
@@ -877,11 +877,21 @@ impl<'a, 'b> Context<'a, 'b> {
                 return ecx.expr_call_global(macsp, path, vec![arg]);
             }
         };
+        let new_fn_name = match trait_ {
+            "Display" => "new_display",
+            "Debug" => "new_debug",
+            "LowerExp" => "new_lower_exp",
+            "UpperExp" => "new_upper_exp",
+            "Octal" => "new_octal",
+            "Pointer" => "new_pointer",
+            "Binary" => "new_binary",
+            "LowerHex" => "new_lower_hex",
+            "UpperHex" => "new_upper_hex",
+            _ => unreachable!(),
+        };
 
-        let path = ecx.std_path(&[sym::fmt, Symbol::intern(trait_), sym::fmt]);
-        let format_fn = ecx.path_global(sp, path);
-        let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, sym::new]);
-        ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
+        let path = ecx.std_path(&[sym::fmt, sym::ArgumentV1, Symbol::intern(new_fn_name)]);
+        ecx.expr_call_global(sp, path, vec![arg])
     }
 }
 
diff --git a/compiler/rustc_mir_transform/src/function_item_references.rs b/compiler/rustc_mir_transform/src/function_item_references.rs
index f364a332a78..5ea0efde9c0 100644
--- a/compiler/rustc_mir_transform/src/function_item_references.rs
+++ b/compiler/rustc_mir_transform/src/function_item_references.rs
@@ -42,54 +42,28 @@ impl<'tcx> Visitor<'tcx> for FunctionItemRefChecker<'_, 'tcx> {
         } = &terminator.kind
         {
             let source_info = *self.body.source_info(location);
-            // Only handle function calls outside macros
-            if !source_info.span.from_expansion() {
-                let func_ty = func.ty(self.body, self.tcx);
-                if let ty::FnDef(def_id, substs_ref) = *func_ty.kind() {
-                    // Handle calls to `transmute`
-                    if self.tcx.is_diagnostic_item(sym::transmute, def_id) {
-                        let arg_ty = args[0].ty(self.body, self.tcx);
-                        for generic_inner_ty in arg_ty.walk() {
-                            if let GenericArgKind::Type(inner_ty) = generic_inner_ty.unpack() {
-                                if let Some((fn_id, fn_substs)) =
-                                    FunctionItemRefChecker::is_fn_ref(inner_ty)
-                                {
-                                    let span = self.nth_arg_span(&args, 0);
-                                    self.emit_lint(fn_id, fn_substs, source_info, span);
-                                }
+            let func_ty = func.ty(self.body, self.tcx);
+            if let ty::FnDef(def_id, substs_ref) = *func_ty.kind() {
+                // Handle calls to `transmute`
+                if self.tcx.is_diagnostic_item(sym::transmute, def_id) {
+                    let arg_ty = args[0].ty(self.body, self.tcx);
+                    for generic_inner_ty in arg_ty.walk() {
+                        if let GenericArgKind::Type(inner_ty) = generic_inner_ty.unpack() {
+                            if let Some((fn_id, fn_substs)) =
+                                FunctionItemRefChecker::is_fn_ref(inner_ty)
+                            {
+                                let span = self.nth_arg_span(&args, 0);
+                                self.emit_lint(fn_id, fn_substs, source_info, span);
                             }
                         }
-                    } else {
-                        self.check_bound_args(def_id, substs_ref, &args, source_info);
                     }
+                } else {
+                    self.check_bound_args(def_id, substs_ref, &args, source_info);
                 }
             }
         }
         self.super_terminator(terminator, location);
     }
-
-    /// Emits a lint for function references formatted with `fmt::Pointer::fmt` by macros. These
-    /// cases are handled as operands instead of call terminators to avoid any dependence on
-    /// unstable, internal formatting details like whether `fmt` is called directly or not.
-    fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location) {
-        let source_info = *self.body.source_info(location);
-        if source_info.span.from_expansion() {
-            let op_ty = operand.ty(self.body, self.tcx);
-            if let ty::FnDef(def_id, substs_ref) = *op_ty.kind() {
-                if self.tcx.is_diagnostic_item(sym::pointer_trait_fmt, def_id) {
-                    let param_ty = substs_ref.type_at(0);
-                    if let Some((fn_id, fn_substs)) = FunctionItemRefChecker::is_fn_ref(param_ty) {
-                        // The operand's ctxt wouldn't display the lint since it's inside a macro so
-                        // we have to use the callsite's ctxt.
-                        let callsite_ctxt = source_info.span.source_callsite().ctxt();
-                        let span = source_info.span.with_ctxt(callsite_ctxt);
-                        self.emit_lint(fn_id, fn_substs, source_info, span);
-                    }
-                }
-            }
-        }
-        self.super_operand(operand, location);
-    }
 }
 
 impl<'tcx> FunctionItemRefChecker<'_, 'tcx> {
@@ -119,7 +93,13 @@ impl<'tcx> FunctionItemRefChecker<'_, 'tcx> {
                                 if let Some((fn_id, fn_substs)) =
                                     FunctionItemRefChecker::is_fn_ref(subst_ty)
                                 {
-                                    let span = self.nth_arg_span(args, arg_num);
+                                    let mut span = self.nth_arg_span(args, arg_num);
+                                    if span.from_expansion() {
+                                        // The operand's ctxt wouldn't display the lint since it's inside a macro so
+                                        // we have to use the callsite's ctxt.
+                                        let callsite_ctxt = span.source_callsite().ctxt();
+                                        span = span.with_ctxt(callsite_ctxt);
+                                    }
                                     self.emit_lint(fn_id, fn_substs, source_info, span);
                                 }
                             }
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 8a2a64f8dc9..e1ea9881303 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -308,9 +308,21 @@ static USIZE_MARKER: fn(&usize, &mut Formatter<'_>) -> Result = |ptr, _| {
     loop {}
 };
 
+macro_rules! arg_new {
+    ($f: ident, $t: ident) => {
+        #[doc(hidden)]
+        #[unstable(feature = "fmt_internals", reason = "internal to format_args!", issue = "none")]
+        #[inline]
+        pub fn $f<'b, T: $t>(x: &'b T) -> ArgumentV1<'_> {
+            Self::new(x, $t::fmt)
+        }
+    };
+}
+
 impl<'a> ArgumentV1<'a> {
     #[doc(hidden)]
     #[unstable(feature = "fmt_internals", reason = "internal to format_args!", issue = "none")]
+    #[inline]
     pub fn new<'b, T>(x: &'b T, f: fn(&T, &mut Formatter<'_>) -> Result) -> ArgumentV1<'b> {
         // SAFETY: `mem::transmute(x)` is safe because
         //     1. `&'b T` keeps the lifetime it originated with `'b`
@@ -323,6 +335,16 @@ impl<'a> ArgumentV1<'a> {
         unsafe { ArgumentV1 { formatter: mem::transmute(f), value: mem::transmute(x) } }
     }
 
+    arg_new!(new_display, Display);
+    arg_new!(new_debug, Debug);
+    arg_new!(new_octal, Octal);
+    arg_new!(new_lower_hex, LowerHex);
+    arg_new!(new_upper_hex, UpperHex);
+    arg_new!(new_pointer, Pointer);
+    arg_new!(new_binary, Binary);
+    arg_new!(new_lower_exp, LowerExp);
+    arg_new!(new_upper_exp, UpperExp);
+
     #[doc(hidden)]
     #[unstable(feature = "fmt_internals", reason = "internal to format_args!", issue = "none")]
     pub fn from_usize(x: &usize) -> ArgumentV1<'_> {
diff --git a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.closure.txt b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.closure.txt
index 7eb393bb448..e463099a5ee 100644
--- a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.closure.txt
+++ b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.closure.txt
@@ -29,8 +29,8 @@
    29|      1|    some_string = Some(String::from("the string content"));
    30|      1|    let
    31|      1|        a
-   32|       |    =
-   33|       |        ||
+   32|      1|    =
+   33|      1|        ||
    34|      0|    {
    35|      0|        let mut countdown = 0;
    36|      0|        if is_false {
@@ -116,8 +116,8 @@
   116|      1|
   117|      1|    let
   118|      1|        _unused_closure
-  119|      1|    =
-  120|      1|        |
+  119|       |    =
+  120|       |        |
   121|       |            mut countdown
   122|       |        |
   123|      0|    {
diff --git a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt
index 768dcb2f608..c2d5143a618 100644
--- a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt
+++ b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_crate.txt
@@ -19,12 +19,12 @@
    18|      2|    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
    19|      2|}
   ------------------
-  | used_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>:
+  | used_crate::used_only_from_bin_crate_generic_function::<&str>:
   |   17|      1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) {
   |   18|      1|    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
   |   19|      1|}
   ------------------
-  | used_crate::used_only_from_bin_crate_generic_function::<&str>:
+  | used_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>:
   |   17|      1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) {
   |   18|      1|    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
   |   19|      1|}
@@ -36,12 +36,12 @@
    22|      2|    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
    23|      2|}
   ------------------
-  | used_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>:
+  | used_crate::used_only_from_this_lib_crate_generic_function::<&str>:
   |   21|      1|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) {
   |   22|      1|    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
   |   23|      1|}
   ------------------
-  | used_crate::used_only_from_this_lib_crate_generic_function::<&str>:
+  | used_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>:
   |   21|      1|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) {
   |   22|      1|    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
   |   23|      1|}
diff --git a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt
index 89636294035..dab31cbf4ac 100644
--- a/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt
+++ b/src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.uses_inline_crate.txt
@@ -42,12 +42,12 @@
    40|      2|    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
    41|      2|}
   ------------------
-  | used_inline_crate::used_only_from_bin_crate_generic_function::<&str>:
+  | used_inline_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>:
   |   39|      1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) {
   |   40|      1|    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
   |   41|      1|}
   ------------------
-  | used_inline_crate::used_only_from_bin_crate_generic_function::<&alloc::vec::Vec<i32>>:
+  | used_inline_crate::used_only_from_bin_crate_generic_function::<&str>:
   |   39|      1|pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) {
   |   40|      1|    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
   |   41|      1|}
@@ -61,12 +61,12 @@
    46|      4|    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
    47|      4|}
   ------------------
-  | used_inline_crate::used_only_from_this_lib_crate_generic_function::<&str>:
+  | used_inline_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>:
   |   45|      2|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) {
   |   46|      2|    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
   |   47|      2|}
   ------------------
-  | used_inline_crate::used_only_from_this_lib_crate_generic_function::<alloc::vec::Vec<i32>>:
+  | used_inline_crate::used_only_from_this_lib_crate_generic_function::<&str>:
   |   45|      2|pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) {
   |   46|      2|    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
   |   47|      2|}
diff --git a/src/test/ui/attributes/key-value-expansion.stderr b/src/test/ui/attributes/key-value-expansion.stderr
index 268e382327e..464e1e1cda7 100644
--- a/src/test/ui/attributes/key-value-expansion.stderr
+++ b/src/test/ui/attributes/key-value-expansion.stderr
@@ -18,8 +18,7 @@ LL | bug!();
 error: unexpected token: `{
            let res =
                ::alloc::fmt::format(::core::fmt::Arguments::new_v1(&[""],
-                                                                   &[::core::fmt::ArgumentV1::new(&"u8",
-                                                                                                  ::core::fmt::Display::fmt)]));
+                                                                   &[::core::fmt::ArgumentV1::new_display(&"u8")]));
            res
        }.as_str()`
   --> $DIR/key-value-expansion.rs:48:23
diff --git a/src/test/ui/closures/print/closure-print-generic-trim-off-verbose-2.stderr b/src/test/ui/closures/print/closure-print-generic-trim-off-verbose-2.stderr
index bdc71b8dcaa..aee782a1c5b 100644
--- a/src/test/ui/closures/print/closure-print-generic-trim-off-verbose-2.stderr
+++ b/src/test/ui/closures/print/closure-print-generic-trim-off-verbose-2.stderr
@@ -9,7 +9,7 @@ LL |         let c1 : () = c;
    |                  expected due to this
    |
    = note: expected unit type `()`
-                found closure `[mod1::f<T>::{closure#0} closure_substs=(unavailable) substs=[T, _#19t, extern "rust-call" fn(()), _#20t]]`
+                found closure `[mod1::f<T>::{closure#0} closure_substs=(unavailable) substs=[T, _#16t, extern "rust-call" fn(()), _#15t]]`
 help: use parentheses to call this closure
    |
 LL |         let c1 : () = c();
diff --git a/src/test/ui/closures/print/closure-print-generic-verbose-2.stderr b/src/test/ui/closures/print/closure-print-generic-verbose-2.stderr
index 453f18891d3..6a994ce718e 100644
--- a/src/test/ui/closures/print/closure-print-generic-verbose-2.stderr
+++ b/src/test/ui/closures/print/closure-print-generic-verbose-2.stderr
@@ -9,7 +9,7 @@ LL |         let c1 : () = c;
    |                  expected due to this
    |
    = note: expected unit type `()`
-                found closure `[f<T>::{closure#0} closure_substs=(unavailable) substs=[T, _#19t, extern "rust-call" fn(()), _#20t]]`
+                found closure `[f<T>::{closure#0} closure_substs=(unavailable) substs=[T, _#16t, extern "rust-call" fn(()), _#15t]]`
 help: use parentheses to call this closure
    |
 LL |         let c1 : () = c();
diff --git a/src/test/ui/fmt/ifmt-unimpl.stderr b/src/test/ui/fmt/ifmt-unimpl.stderr
index bee165437cb..6e8dd792191 100644
--- a/src/test/ui/fmt/ifmt-unimpl.stderr
+++ b/src/test/ui/fmt/ifmt-unimpl.stderr
@@ -5,6 +5,11 @@ LL |     format!("{:X}", "3");
    |                     ^^^ the trait `UpperHex` is not implemented for `str`
    |
    = note: required because of the requirements on the impl of `UpperHex` for `&str`
+note: required by a bound in `ArgumentV1::<'a>::new_upper_hex`
+  --> $SRC_DIR/core/src/fmt/mod.rs:LL:COL
+   |
+LL |     arg_new!(new_upper_hex, UpperHex);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `ArgumentV1::<'a>::new_upper_hex`
    = note: this error originates in the macro `$crate::__export::format_args` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
diff --git a/src/test/ui/issues/issue-69455.stderr b/src/test/ui/issues/issue-69455.stderr
index 95617e4ecc8..378fdc97dd3 100644
--- a/src/test/ui/issues/issue-69455.stderr
+++ b/src/test/ui/issues/issue-69455.stderr
@@ -1,14 +1,14 @@
 error[E0282]: type annotations needed
-  --> $DIR/issue-69455.rs:29:5
+  --> $DIR/issue-69455.rs:29:20
    |
 LL |     type Output;
    |     ------------ `<Self as Test<Rhs>>::Output` defined here
 ...
 LL |     println!("{}", 23u64.test(xs.iter().sum()));
-   |     ^^^^^^^^^^^^^^^---------------------------^
-   |     |              |
-   |     |              this method call resolves to `<Self as Test<Rhs>>::Output`
-   |     cannot infer type for type parameter `T` declared on the associated function `new`
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                    |
+   |                    this method call resolves to `<Self as Test<Rhs>>::Output`
+   |                    cannot infer type for type parameter `T` declared on the associated function `new_display`
    |
    = note: this error originates in the macro `$crate::format_args_nl` (in Nightly builds, run with -Z macro-backtrace for more info)
 
diff --git a/src/tools/clippy/clippy_utils/src/macros.rs b/src/tools/clippy/clippy_utils/src/macros.rs
index b7a242cf90a..a75f6b86a9b 100644
--- a/src/tools/clippy/clippy_utils/src/macros.rs
+++ b/src/tools/clippy/clippy_utils/src/macros.rs
@@ -339,15 +339,13 @@ impl<'tcx> FormatArgsExpn<'tcx> {
         expr_visitor_no_bodies(|e| {
             // if we're still inside of the macro definition...
             if e.span.ctxt() == expr.span.ctxt() {
-                // ArgumnetV1::new(<value>, <format_trait>::fmt)
+                // ArgumnetV1::new_<format_trait>(<value>)
                 if_chain! {
-                    if let ExprKind::Call(callee, [val, fmt_path]) = e.kind;
+                    if let ExprKind::Call(callee, [val]) = e.kind;
                     if let ExprKind::Path(QPath::TypeRelative(ty, seg)) = callee.kind;
-                    if seg.ident.name == sym::new;
                     if let hir::TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
                     if path.segments.last().unwrap().ident.name == sym::ArgumentV1;
-                    if let ExprKind::Path(QPath::Resolved(_, path)) = fmt_path.kind;
-                    if let [.., fmt_trait, _fmt] = path.segments;
+                    if seg.ident.name.as_str().starts_with("new_");
                     then {
                         let val_idx = if_chain! {
                             if val.span.ctxt() == expr.span.ctxt();
@@ -361,7 +359,19 @@ impl<'tcx> FormatArgsExpn<'tcx> {
                                 formatters.len()
                             }
                         };
-                        formatters.push((val_idx, fmt_trait.ident.name));
+                        let fmt_trait = match seg.ident.name.as_str() {
+                            "new_display" => "Display",
+                            "new_debug" => "Debug",
+                            "new_lower_exp" => "LowerExp",
+                            "new_upper_exp" => "UpperExp",
+                            "new_octal" => "Octal",
+                            "new_pointer" => "Pointer",
+                            "new_binary" => "Binary",
+                            "new_lower_hex" => "LowerHex",
+                            "new_upper_hex" => "UpperHex",
+                            _ => unreachable!(),
+                        };
+                        formatters.push((val_idx, Symbol::intern(fmt_trait)));
                     }
                 }
                 if let ExprKind::Struct(QPath::Resolved(_, path), ..) = e.kind {