From 1f107b1ef3af6f297473c98867a94a62e329dd17 Mon Sep 17 00:00:00 2001 From: yukang Date: Sat, 5 Aug 2023 19:07:42 +0800 Subject: [PATCH] Remove the unhelpful let binding diag comes from FormatArguments --- .../src/diagnostics/conflict_errors.rs | 50 ++++++++++++++----- .../issue-114374-invalid-help-fmt-args.rs | 16 ++++++ .../issue-114374-invalid-help-fmt-args.stderr | 33 ++++++++++++ 3 files changed, 86 insertions(+), 13 deletions(-) create mode 100644 tests/ui/borrowck/issue-114374-invalid-help-fmt-args.rs create mode 100644 tests/ui/borrowck/issue-114374-invalid-help-fmt-args.stderr diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs index fe4a45b3898..48d09f2c2b2 100644 --- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs @@ -2130,21 +2130,27 @@ fn report_temporary_value_does_not_live_long_enough( /// misleading users in cases like `tests/ui/nll/borrowed-temporary-error.rs`. /// We could expand the analysis to suggest hoising all of the relevant parts of /// the users' code to make the code compile, but that could be too much. - struct NestedStatementVisitor { + /// We found the `prop_expr` by the way to check whether the expression is a `FormatArguments`, + /// which is a special case since it's generated by the compiler. + struct NestedStatementVisitor<'tcx> { span: Span, current: usize, found: usize, + prop_expr: Option<&'tcx hir::Expr<'tcx>>, } - impl<'tcx> Visitor<'tcx> for NestedStatementVisitor { - fn visit_block(&mut self, block: &hir::Block<'tcx>) { + impl<'tcx> Visitor<'tcx> for NestedStatementVisitor<'tcx> { + fn visit_block(&mut self, block: &'tcx hir::Block<'tcx>) { self.current += 1; walk_block(self, block); self.current -= 1; } - fn visit_expr(&mut self, expr: &hir::Expr<'tcx>) { + fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) { if self.span == expr.span.source_callsite() { self.found = self.current; + if self.prop_expr.is_none() { + self.prop_expr = Some(expr); + } } walk_expr(self, expr); } @@ -2162,22 +2168,40 @@ fn visit_expr(&mut self, expr: &hir::Expr<'tcx>) { span: proper_span, current: 0, found: 0, + prop_expr: None, }; visitor.visit_stmt(stmt); + + let typeck_results = self.infcx.tcx.typeck(self.mir_def_id()); + let expr_ty: Option> = visitor.prop_expr.map(|expr| typeck_results.expr_ty(expr).peel_refs()); + + let is_format_arguments_item = + if let Some(expr_ty) = expr_ty + && let ty::Adt(adt, _) = expr_ty.kind() { + self.infcx.tcx.lang_items().get(LangItem::FormatArguments) == Some(adt.did()) + } else { + false + }; + if visitor.found == 0 && stmt.span.contains(proper_span) && let Some(p) = sm.span_to_margin(stmt.span) && let Ok(s) = sm.span_to_snippet(proper_span) { - let addition = format!("let binding = {};\n{}", s, " ".repeat(p)); - err.multipart_suggestion_verbose( - msg, - vec![ - (stmt.span.shrink_to_lo(), addition), - (proper_span, "binding".to_string()), - ], - Applicability::MaybeIncorrect, - ); + if !is_format_arguments_item { + let addition = format!("let binding = {};\n{}", s, " ".repeat(p)); + err.multipart_suggestion_verbose( + msg, + vec![ + (stmt.span.shrink_to_lo(), addition), + (proper_span, "binding".to_string()), + ], + Applicability::MaybeIncorrect, + ); + } else { + err.note("the result of `format_args!` can only be assigned directly if no placeholders in it's arguments are used"); + err.note("to learn more, visit "); + } suggested = true; break; } diff --git a/tests/ui/borrowck/issue-114374-invalid-help-fmt-args.rs b/tests/ui/borrowck/issue-114374-invalid-help-fmt-args.rs new file mode 100644 index 00000000000..4a6c2f9ed06 --- /dev/null +++ b/tests/ui/borrowck/issue-114374-invalid-help-fmt-args.rs @@ -0,0 +1,16 @@ +#![allow(dead_code)] + +fn bar<'a>(_: std::fmt::Arguments<'a>) {} +fn main() { + let x = format_args!("a {} {} {}.", 1, format_args!("b{}!", 2), 3); + //~^ ERROR temporary value dropped while borrowed + + bar(x); + + let foo = format_args!("{}", "hi"); + //~^ ERROR temporary value dropped while borrowed + bar(foo); + + let foo = format_args!("hi"); // no placeholder in arguments, so no error + bar(foo); +} diff --git a/tests/ui/borrowck/issue-114374-invalid-help-fmt-args.stderr b/tests/ui/borrowck/issue-114374-invalid-help-fmt-args.stderr new file mode 100644 index 00000000000..8221505b100 --- /dev/null +++ b/tests/ui/borrowck/issue-114374-invalid-help-fmt-args.stderr @@ -0,0 +1,33 @@ +error[E0716]: temporary value dropped while borrowed + --> $DIR/issue-114374-invalid-help-fmt-args.rs:5:13 + | +LL | let x = format_args!("a {} {} {}.", 1, format_args!("b{}!", 2), 3); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- temporary value is freed at the end of this statement + | | + | creates a temporary value which is freed while still in use +... +LL | bar(x); + | - borrow later used here + | + = note: the result of `format_args!` can only be assigned directly if no placeholders in it's arguments are used + = note: to learn more, visit + = note: this error originates in the macro `format_args` (in Nightly builds, run with -Z macro-backtrace for more info) + +error[E0716]: temporary value dropped while borrowed + --> $DIR/issue-114374-invalid-help-fmt-args.rs:10:15 + | +LL | let foo = format_args!("{}", "hi"); + | ^^^^^^^^^^^^^^^^^^^^^^^^- temporary value is freed at the end of this statement + | | + | creates a temporary value which is freed while still in use +LL | +LL | bar(foo); + | --- borrow later used here + | + = note: the result of `format_args!` can only be assigned directly if no placeholders in it's arguments are used + = note: to learn more, visit + = note: this error originates in the macro `format_args` (in Nightly builds, run with -Z macro-backtrace for more info) + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0716`.