mirror of
https://github.com/rust-lang/rust
synced 2024-10-01 14:25:08 +00:00
Add format_args_capture
feature
This commit is contained in:
parent
1557fb031b
commit
6b95f3102d
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@ -107,6 +107,9 @@ struct Context<'a, 'b> {
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arg_spans: Vec<Span>,
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/// All the formatting arguments that have formatting flags set, in order for diagnostics.
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arg_with_formatting: Vec<parse::FormatSpec<'a>>,
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/// Whether this format string came from a string literal, as opposed to a macro.
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is_literal: bool,
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}
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/// Parses the arguments from the given list of tokens, returning the diagnostic
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@ -498,10 +501,59 @@ fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
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self.verify_arg_type(Exact(idx), ty)
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}
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None => {
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let msg = format!("there is no argument named `{}`", name);
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let sp = *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp);
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let mut err = self.ecx.struct_span_err(sp, &msg[..]);
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err.emit();
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let capture_feature_enabled = self
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.ecx
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.ecfg
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.features
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.map_or(false, |features| features.format_args_capture);
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// For the moment capturing variables from format strings expanded from
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// literals is disabled (see RFC #2795)
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let can_capture = capture_feature_enabled && self.is_literal;
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if can_capture {
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// Treat this name as a variable to capture from the surrounding scope
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let idx = self.args.len();
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self.arg_types.push(Vec::new());
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self.arg_unique_types.push(Vec::new());
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self.args.push(
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self.ecx.expr_ident(self.fmtsp, Ident::new(name, self.fmtsp)),
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);
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self.names.insert(name, idx);
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self.verify_arg_type(Exact(idx), ty)
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} else {
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let msg = format!("there is no argument named `{}`", name);
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let sp = if self.is_literal {
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*self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
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} else {
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self.fmtsp
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};
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let mut err = self.ecx.struct_span_err(sp, &msg[..]);
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if capture_feature_enabled && !self.is_literal {
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err.note(&format!(
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"did you intend to capture a variable `{}` from \
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the surrounding scope?",
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name
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));
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err.note(
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"for hygiene reasons format_args! cannot capture variables \
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when the format string is expanded from a macro",
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);
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} else if self.ecx.parse_sess().unstable_features.is_nightly_build() {
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err.note(&format!(
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"did you intend to capture a variable `{}` from \
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the surrounding scope?",
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name
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));
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err.help(
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"add `#![feature(format_args_capture)]` to the crate \
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attributes to enable",
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);
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}
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err.emit();
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}
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}
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}
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}
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@ -951,6 +1003,7 @@ pub fn expand_preparsed_format_args(
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invalid_refs: Vec::new(),
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arg_spans,
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arg_with_formatting: Vec::new(),
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is_literal: parser.is_literal,
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};
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// This needs to happen *after* the Parser has consumed all pieces to create all the spans
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@ -577,6 +577,9 @@ pub fn set(&self, features: &mut Features, span: Span) {
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/// Be more precise when looking for live drops in a const context.
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(active, const_precise_live_drops, "1.46.0", Some(73255), None),
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/// Allows capturing variables in scope using format_args!
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(active, format_args_capture, "1.46.0", Some(67984), None),
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// -------------------------------------------------------------------------
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// feature-group-end: actual feature gates
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// -------------------------------------------------------------------------
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@ -190,7 +190,7 @@ pub struct Parser<'a> {
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/// Whether the source string is comes from `println!` as opposed to `format!` or `print!`
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append_newline: bool,
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/// Whether this formatting string is a literal or it comes from a macro.
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is_literal: bool,
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pub is_literal: bool,
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/// Start position of the current line.
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cur_line_start: usize,
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/// Start and end byte offset of every line of the format string. Excludes
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@ -338,6 +338,7 @@
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forbid,
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format_args,
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format_args_nl,
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format_args_capture,
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from,
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From,
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from_desugaring,
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6
src/test/ui/fmt/feature-gate-format-args-capture.rs
Normal file
6
src/test/ui/fmt/feature-gate-format-args-capture.rs
Normal file
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@ -0,0 +1,6 @@
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fn main() {
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format!("{foo}"); //~ ERROR: there is no argument named `foo`
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// panic! doesn't hit format_args! unless there are two or more arguments.
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panic!("{foo} {bar}", bar=1); //~ ERROR: there is no argument named `foo`
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}
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20
src/test/ui/fmt/feature-gate-format-args-capture.stderr
Normal file
20
src/test/ui/fmt/feature-gate-format-args-capture.stderr
Normal file
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@ -0,0 +1,20 @@
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error: there is no argument named `foo`
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--> $DIR/feature-gate-format-args-capture.rs:2:14
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LL | format!("{foo}");
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| ^^^^^
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= note: did you intend to capture a variable `foo` from the surrounding scope?
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= help: add `#![feature(format_args_capture)]` to the crate attributes to enable
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error: there is no argument named `foo`
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--> $DIR/feature-gate-format-args-capture.rs:5:13
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LL | panic!("{foo} {bar}", bar=1);
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| ^^^^^
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= note: did you intend to capture a variable `foo` from the surrounding scope?
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= help: add `#![feature(format_args_capture)]` to the crate attributes to enable
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error: aborting due to 2 previous errors
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6
src/test/ui/fmt/format-args-capture-macro-hygiene.rs
Normal file
6
src/test/ui/fmt/format-args-capture-macro-hygiene.rs
Normal file
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@ -0,0 +1,6 @@
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#![feature(format_args_capture)]
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fn main() {
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format!(concat!("{foo}")); //~ ERROR: there is no argument named `foo`
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format!(concat!("{ba", "r} {}"), 1); //~ ERROR: there is no argument named `bar`
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}
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22
src/test/ui/fmt/format-args-capture-macro-hygiene.stderr
Normal file
22
src/test/ui/fmt/format-args-capture-macro-hygiene.stderr
Normal file
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@ -0,0 +1,22 @@
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error: there is no argument named `foo`
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--> $DIR/format-args-capture-macro-hygiene.rs:4:13
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LL | format!(concat!("{foo}"));
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| ^^^^^^^^^^^^^^^^
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= note: did you intend to capture a variable `foo` from the surrounding scope?
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= note: for hygiene reasons format_args! cannot capture variables when the format string is expanded from a macro
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= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
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error: there is no argument named `bar`
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--> $DIR/format-args-capture-macro-hygiene.rs:5:13
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LL | format!(concat!("{ba", "r} {}"), 1);
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| ^^^^^^^^^^^^^^^^^^^^^^^
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= note: did you intend to capture a variable `bar` from the surrounding scope?
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= note: for hygiene reasons format_args! cannot capture variables when the format string is expanded from a macro
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= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
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error: aborting due to 2 previous errors
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22
src/test/ui/fmt/format-args-capture-missing-variables.rs
Normal file
22
src/test/ui/fmt/format-args-capture-missing-variables.rs
Normal file
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@ -0,0 +1,22 @@
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#![feature(format_args_capture)]
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fn main() {
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format!("{} {foo} {} {bar} {}", 1, 2, 3);
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//~^ ERROR: cannot find value `foo` in this scope
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//~^^ ERROR: cannot find value `bar` in this scope
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format!("{foo}"); //~ ERROR: cannot find value `foo` in this scope
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format!("{valuea} {valueb}", valuea=5, valuec=7);
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//~^ ERROR cannot find value `valueb` in this scope
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//~^^ ERROR named argument never used
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format!(r##"
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{foo}
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"##);
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//~^^^^^ ERROR: cannot find value `foo` in this scope
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panic!("{foo} {bar}", bar=1); //~ ERROR: cannot find value `foo` in this scope
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}
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52
src/test/ui/fmt/format-args-capture-missing-variables.stderr
Normal file
52
src/test/ui/fmt/format-args-capture-missing-variables.stderr
Normal file
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@ -0,0 +1,52 @@
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error: named argument never used
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--> $DIR/format-args-capture-missing-variables.rs:10:51
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LL | format!("{valuea} {valueb}", valuea=5, valuec=7);
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| ------------------- ^ named argument never used
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| |
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| formatting specifier missing
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error[E0425]: cannot find value `foo` in this scope
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--> $DIR/format-args-capture-missing-variables.rs:4:13
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LL | format!("{} {foo} {} {bar} {}", 1, 2, 3);
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| ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
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error[E0425]: cannot find value `bar` in this scope
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--> $DIR/format-args-capture-missing-variables.rs:4:13
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LL | format!("{} {foo} {} {bar} {}", 1, 2, 3);
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| ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
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error[E0425]: cannot find value `foo` in this scope
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--> $DIR/format-args-capture-missing-variables.rs:8:13
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LL | format!("{foo}");
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| ^^^^^^^ not found in this scope
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error[E0425]: cannot find value `valueb` in this scope
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--> $DIR/format-args-capture-missing-variables.rs:10:13
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LL | format!("{valuea} {valueb}", valuea=5, valuec=7);
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| ^^^^^^^^^^^^^^^^^^^ not found in this scope
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error[E0425]: cannot find value `foo` in this scope
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--> $DIR/format-args-capture-missing-variables.rs:14:13
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LL | format!(r##"
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| _____________^
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LL | |
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LL | | {foo}
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LL | |
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LL | | "##);
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| |_______^ not found in this scope
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error[E0425]: cannot find value `foo` in this scope
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--> $DIR/format-args-capture-missing-variables.rs:21:12
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LL | panic!("{foo} {bar}", bar=1);
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| ^^^^^^^^^^^^^ not found in this scope
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error: aborting due to 7 previous errors
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For more information about this error, try `rustc --explain E0425`.
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62
src/test/ui/fmt/format-args-capture.rs
Normal file
62
src/test/ui/fmt/format-args-capture.rs
Normal file
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@ -0,0 +1,62 @@
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// run-pass
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#![feature(format_args_capture)]
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fn main() {
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named_argument_takes_precedence_to_captured();
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panic_with_single_argument_does_not_get_formatted();
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panic_with_multiple_arguments_is_formatted();
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formatting_parameters_can_be_captured();
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}
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fn named_argument_takes_precedence_to_captured() {
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let foo = "captured";
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let s = format!("{foo}", foo="named");
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assert_eq!(&s, "named");
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let s = format!("{foo}-{foo}-{foo}", foo="named");
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assert_eq!(&s, "named-named-named");
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let s = format!("{}-{bar}-{foo}", "positional", bar="named");
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assert_eq!(&s, "positional-named-captured");
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}
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fn panic_with_single_argument_does_not_get_formatted() {
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// panic! with a single argument does not perform string formatting.
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// RFC #2795 suggests that this may need to change so that captured arguments are formatted.
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// For stability reasons this will need to part of an edition change.
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let msg = std::panic::catch_unwind(|| {
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panic!("{foo}");
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}).unwrap_err();
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assert_eq!(msg.downcast_ref::<&str>(), Some(&"{foo}"))
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}
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fn panic_with_multiple_arguments_is_formatted() {
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let foo = "captured";
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let msg = std::panic::catch_unwind(|| {
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panic!("{}-{bar}-{foo}", "positional", bar="named");
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}).unwrap_err();
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assert_eq!(msg.downcast_ref::<String>(), Some(&"positional-named-captured".to_string()))
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}
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fn formatting_parameters_can_be_captured() {
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let width = 9;
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let precision = 3;
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let x = 7.0;
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let s = format!("{x:width$}");
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assert_eq!(&s, " 7");
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let s = format!("{x:<width$}");
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assert_eq!(&s, "7 ");
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let s = format!("{x:-^width$}");
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assert_eq!(&s, "----7----");
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let s = format!("{x:-^width$.precision$}");
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assert_eq!(&s, "--7.000--");
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}
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@ -63,18 +63,27 @@ error: there is no argument named `foo`
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LL | format!("{} {foo} {} {bar} {}", 1, 2, 3);
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| ^^^^^
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= note: did you intend to capture a variable `foo` from the surrounding scope?
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= help: add `#![feature(format_args_capture)]` to the crate attributes to enable
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error: there is no argument named `bar`
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--> $DIR/ifmt-bad-arg.rs:27:26
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LL | format!("{} {foo} {} {bar} {}", 1, 2, 3);
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| ^^^^^
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= note: did you intend to capture a variable `bar` from the surrounding scope?
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= help: add `#![feature(format_args_capture)]` to the crate attributes to enable
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error: there is no argument named `foo`
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--> $DIR/ifmt-bad-arg.rs:31:14
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LL | format!("{foo}");
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| ^^^^^
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= note: did you intend to capture a variable `foo` from the surrounding scope?
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= help: add `#![feature(format_args_capture)]` to the crate attributes to enable
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error: multiple unused formatting arguments
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--> $DIR/ifmt-bad-arg.rs:32:17
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@ -155,6 +164,9 @@ error: there is no argument named `valueb`
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LL | format!("{valuea} {valueb}", valuea=5, valuec=7);
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| ^^^^^^^^
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= note: did you intend to capture a variable `valueb` from the surrounding scope?
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= help: add `#![feature(format_args_capture)]` to the crate attributes to enable
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error: named argument never used
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--> $DIR/ifmt-bad-arg.rs:45:51
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@ -205,6 +217,9 @@ error: there is no argument named `foo`
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LL | {foo}
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| ^^^^^
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= note: did you intend to capture a variable `foo` from the surrounding scope?
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= help: add `#![feature(format_args_capture)]` to the crate attributes to enable
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error: invalid format string: expected `'}'`, found `'t'`
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--> $DIR/ifmt-bad-arg.rs:75:1
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