Extended temporary argument to format_args!() in all cases

compiler/rustc_ast_lowering/src/format.rs

@@ -487,26 +487,6 @@ fn expand_format_args<'hir>(
         // Generate:
         //     []
         (vec![], ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Array(&[]))))
-    } else if argmap.len() == 1 && arguments.len() == 1 {
-        // Only one argument, so we don't need to make the `args` tuple.
-        //
-        // Generate:
-        //     super let args = [<core::fmt::Argument>::new_display(&arg)];
-        let args = ctx.arena.alloc_from_iter(argmap.iter().map(
-            |(&(arg_index, ty), &placeholder_span)| {
-                let arg = &arguments[arg_index];
-                let placeholder_span =
-                    placeholder_span.unwrap_or(arg.expr.span).with_ctxt(macsp.ctxt());
-                let arg = ctx.lower_expr(&arg.expr);
-                let ref_arg = ctx.arena.alloc(ctx.expr_ref(arg.span.with_ctxt(macsp.ctxt()), arg));
-                make_argument(ctx, placeholder_span, ref_arg, ty)
-            },
-        ));
-        let args = ctx.arena.alloc(ctx.expr(macsp, hir::ExprKind::Array(args)));
-        let args_ident = Ident::new(sym::args, macsp);
-        let (args_pat, args_hir_id) = ctx.pat_ident(macsp, args_ident);
-        let let_statement = ctx.stmt_super_let_pat(macsp, args_pat, Some(args));
-        (vec![let_statement], ctx.arena.alloc(ctx.expr_ident_mut(macsp, args_ident, args_hir_id)))
     } else {
         // Generate:
         //     super let args = (&arg0, &arg1, &…);

library/coretests/tests/fmt/mod.rs

@@ -12,6 +12,12 @@ fn test_lifetime() {
     let a = format_args!("hello {a} {a:?}");
     assert_eq!(a.to_string(), "hello hello hello hello hello hello hello");
 
+    // Check that temporaries as arguments are extended.
+    let b = format_args!("{}", String::new());
+    let c = format_args!("{}{}", String::new(), String::new());
+    assert_eq!(b.to_string(), "");
+    assert_eq!(c.to_string(), "");
+
     // Without arguments, it should also work in consts.
     const A: std::fmt::Arguments<'static> = format_args!("hello");
     assert_eq!(A.to_string(), "hello");

src/tools/clippy/tests/ui/author/macro_in_closure.stdout

@@ -10,34 +10,42 @@ if let StmtKind::Let(local) = stmt.kind
     && paths::STD_IO_STDIO__PRINT.matches_path(cx, func) // Add the path to `clippy_utils::paths` if needed
     && args.len() == 1
     && let ExprKind::Block(block1, None) = args[0].kind
-    && block1.stmts.len() == 1
+    && block1.stmts.len() == 2
     && let StmtKind::Let(local1) = block1.stmts[0].kind
     && let Some(init1) = local1.init
-    && let ExprKind::Array(elements) = init1.kind
+    && let ExprKind::Tup(elements) = init1.kind
     && elements.len() == 1
-    && let ExprKind::Call(func1, args1) = elements[0].kind
-    && paths::CORE_FMT_RT_ARGUMENT_NEW_DISPLAY.matches_path(cx, func1) // Add the path to `clippy_utils::paths` if needed
-    && args1.len() == 1
-    && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = args1[0].kind
+    && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = elements[0].kind
     && let PatKind::Binding(BindingMode::NONE, _, name, None) = local1.pat.kind
     && name.as_str() == "args"
+    && let StmtKind::Let(local2) = block1.stmts[1].kind
+    && let Some(init2) = local2.init
+    && let ExprKind::Array(elements1) = init2.kind
+    && elements1.len() == 1
+    && let ExprKind::Call(func1, args1) = elements1[0].kind
+    && paths::CORE_FMT_RT_ARGUMENT_NEW_DISPLAY.matches_path(cx, func1) // Add the path to `clippy_utils::paths` if needed
+    && args1.len() == 1
+    && let ExprKind::Field(object, field_name) = args1[0].kind
+    && field_name.as_str() == "0"
+    && let PatKind::Binding(BindingMode::NONE, _, name1, None) = local2.pat.kind
+    && name1.as_str() == "args"
     && let Some(trailing_expr) = block1.expr
     && let ExprKind::Call(func2, args2) = trailing_expr.kind
     && paths::CORE_FMT_RT_NEW_V1.matches_path(cx, func2) // Add the path to `clippy_utils::paths` if needed
     && args2.len() == 2
     && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner1) = args2[0].kind
-    && let ExprKind::Array(elements1) = inner1.kind
-    && elements1.len() == 2
-    && let ExprKind::Lit(ref lit) = elements1[0].kind
+    && let ExprKind::Array(elements2) = inner1.kind
+    && elements2.len() == 2
+    && let ExprKind::Lit(ref lit) = elements2[0].kind
     && let LitKind::Str(s, _) = lit.node
     && s.as_str() == ""
-    && let ExprKind::Lit(ref lit1) = elements1[1].kind
+    && let ExprKind::Lit(ref lit1) = elements2[1].kind
     && let LitKind::Str(s1, _) = lit1.node
     && s1.as_str() == "\n"
     && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner2) = args2[1].kind
     && block.expr.is_none()
-    && let PatKind::Binding(BindingMode::NONE, _, name1, None) = local.pat.kind
-    && name1.as_str() == "print_text"
+    && let PatKind::Binding(BindingMode::NONE, _, name2, None) = local.pat.kind
+    && name2.as_str() == "print_text"
 {
     // report your lint here
 }

src/tools/clippy/tests/ui/author/macro_in_loop.stdout

@@ -20,28 +20,36 @@ if let Some(higher::ForLoop { pat: pat, arg: arg, body: body, .. }) = higher::Fo
     && paths::STD_IO_STDIO__PRINT.matches_path(cx, func) // Add the path to `clippy_utils::paths` if needed
     && args.len() == 1
     && let ExprKind::Block(block2, None) = args[0].kind
-    && block2.stmts.len() == 1
+    && block2.stmts.len() == 2
     && let StmtKind::Let(local) = block2.stmts[0].kind
     && let Some(init) = local.init
-    && let ExprKind::Array(elements) = init.kind
+    && let ExprKind::Tup(elements) = init.kind
     && elements.len() == 1
-    && let ExprKind::Call(func1, args1) = elements[0].kind
-    && paths::CORE_FMT_RT_ARGUMENT_NEW_DISPLAY.matches_path(cx, func1) // Add the path to `clippy_utils::paths` if needed
-    && args1.len() == 1
-    && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = args1[0].kind
+    && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = elements[0].kind
     && let PatKind::Binding(BindingMode::NONE, _, name1, None) = local.pat.kind
     && name1.as_str() == "args"
+    && let StmtKind::Let(local1) = block2.stmts[1].kind
+    && let Some(init1) = local1.init
+    && let ExprKind::Array(elements1) = init1.kind
+    && elements1.len() == 1
+    && let ExprKind::Call(func1, args1) = elements1[0].kind
+    && paths::CORE_FMT_RT_ARGUMENT_NEW_DISPLAY.matches_path(cx, func1) // Add the path to `clippy_utils::paths` if needed
+    && args1.len() == 1
+    && let ExprKind::Field(object, field_name) = args1[0].kind
+    && field_name.as_str() == "0"
+    && let PatKind::Binding(BindingMode::NONE, _, name2, None) = local1.pat.kind
+    && name2.as_str() == "args"
     && let Some(trailing_expr) = block2.expr
     && let ExprKind::Call(func2, args2) = trailing_expr.kind
     && paths::CORE_FMT_RT_NEW_V1.matches_path(cx, func2) // Add the path to `clippy_utils::paths` if needed
     && args2.len() == 2
     && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner1) = args2[0].kind
-    && let ExprKind::Array(elements1) = inner1.kind
-    && elements1.len() == 2
-    && let ExprKind::Lit(ref lit2) = elements1[0].kind
+    && let ExprKind::Array(elements2) = inner1.kind
+    && elements2.len() == 2
+    && let ExprKind::Lit(ref lit2) = elements2[0].kind
     && let LitKind::Str(s, _) = lit2.node
     && s.as_str() == ""
-    && let ExprKind::Lit(ref lit3) = elements1[1].kind
+    && let ExprKind::Lit(ref lit3) = elements2[1].kind
     && let LitKind::Str(s1, _) = lit3.node
     && s1.as_str() == "\n"
     && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner2) = args2[1].kind

tests/coverage/issue-83601.cov-map

@@ -1,30 +1,22 @@
 Function name: issue_83601::main
-Raw bytes (76): 0x[01, 01, 01, 05, 09, 0e, 01, 06, 01, 00, 0a, 01, 01, 09, 00, 0c, 01, 00, 0f, 00, 15, 01, 01, 05, 00, 0f, 05, 01, 09, 00, 0c, 05, 00, 0f, 00, 15, 05, 01, 05, 00, 0f, 02, 01, 05, 00, 0d, 02, 00, 0e, 00, 14, 02, 01, 05, 00, 0d, 02, 00, 0e, 00, 14, 02, 01, 05, 00, 0d, 02, 00, 0e, 00, 14, 02, 01, 01, 00, 02]
+Raw bytes (74): 0x[01, 01, 00, 0e, 01, 06, 01, 00, 0a, 01, 01, 09, 00, 0c, 01, 00, 0f, 00, 15, 01, 01, 05, 00, 0f, 01, 01, 09, 00, 0c, 01, 00, 0f, 00, 15, 01, 01, 05, 00, 0f, 01, 01, 05, 00, 0d, 01, 00, 0e, 00, 14, 01, 01, 05, 00, 0d, 01, 00, 0e, 00, 14, 01, 01, 05, 00, 0d, 01, 00, 0e, 00, 14, 01, 01, 01, 00, 02]
 Number of files: 1
 - file 0 => $DIR/issue-83601.rs
-Number of expressions: 1
-- expression 0 operands: lhs = Counter(1), rhs = Counter(2)
+Number of expressions: 0
 Number of file 0 mappings: 14
 - Code(Counter(0)) at (prev + 6, 1) to (start + 0, 10)
 - Code(Counter(0)) at (prev + 1, 9) to (start + 0, 12)
 - Code(Counter(0)) at (prev + 0, 15) to (start + 0, 21)
 - Code(Counter(0)) at (prev + 1, 5) to (start + 0, 15)
-- Code(Counter(1)) at (prev + 1, 9) to (start + 0, 12)
-- Code(Counter(1)) at (prev + 0, 15) to (start + 0, 21)
-- Code(Counter(1)) at (prev + 1, 5) to (start + 0, 15)
-- Code(Expression(0, Sub)) at (prev + 1, 5) to (start + 0, 13)
-    = (c1 - c2)
-- Code(Expression(0, Sub)) at (prev + 0, 14) to (start + 0, 20)
-    = (c1 - c2)
-- Code(Expression(0, Sub)) at (prev + 1, 5) to (start + 0, 13)
-    = (c1 - c2)
-- Code(Expression(0, Sub)) at (prev + 0, 14) to (start + 0, 20)
-    = (c1 - c2)
-- Code(Expression(0, Sub)) at (prev + 1, 5) to (start + 0, 13)
-    = (c1 - c2)
-- Code(Expression(0, Sub)) at (prev + 0, 14) to (start + 0, 20)
-    = (c1 - c2)
-- Code(Expression(0, Sub)) at (prev + 1, 1) to (start + 0, 2)
-    = (c1 - c2)
-Highest counter ID seen: c1
+- Code(Counter(0)) at (prev + 1, 9) to (start + 0, 12)
+- Code(Counter(0)) at (prev + 0, 15) to (start + 0, 21)
+- Code(Counter(0)) at (prev + 1, 5) to (start + 0, 15)
+- Code(Counter(0)) at (prev + 1, 5) to (start + 0, 13)
+- Code(Counter(0)) at (prev + 0, 14) to (start + 0, 20)
+- Code(Counter(0)) at (prev + 1, 5) to (start + 0, 13)
+- Code(Counter(0)) at (prev + 0, 14) to (start + 0, 20)
+- Code(Counter(0)) at (prev + 1, 5) to (start + 0, 13)
+- Code(Counter(0)) at (prev + 0, 14) to (start + 0, 20)
+- Code(Counter(0)) at (prev + 1, 1) to (start + 0, 2)
+Highest counter ID seen: c0