mirror of
https://github.com/rust-lang/rust
synced 2024-10-14 20:46:49 +00:00
Auto merge of #119105 - dtolnay:paren, r=WaffleLapkin
Fix parenthesization of subexprs containing statement boundary This PR fixes a multitude of false negatives and false positives in the AST pretty printer's parenthesis insertion related to statement boundaries — statements which terminate unexpectedly early if there aren't parentheses. Without this fix, the AST pretty printer (including both `stringify!` and `rustc -Zunpretty=expanded`) is prone to producing output which is not syntactically valid Rust. Invalid output is problematic because it means Rustfmt is unable to parse the output of `cargo expand`, for example, causing friction by forcing someone trying to debug a macro into reading poorly formatted code. I believe the set of bugs fixed in this PR account for the most prevalent reason that `cargo expand` produces invalid output in real-world usage. Fixes #98790. ## False negatives The following is a correct program — `cargo check` succeeds. ```rust macro_rules! m { ($e:expr) => { match () { _ => $e } }; } fn main() { m!({ 1 } - 1); } ``` But `rustc -Zunpretty=expanded main.rs` produces output that is invalid Rust syntax, because parenthesization is needed and not being done by the pretty printer. ```rust fn main() { match () { _ => { 1 } - 1, }; } ``` Piping this expanded code to rustfmt, it fails to parse. ```console error: unexpected `,` in pattern --> <stdin>:1:38 | 1 | fn main() { match () { _ => { 1 } - 1, }; } | ^ | help: try adding parentheses to match on a tuple... | 1 | fn main() { match () { _ => { 1 } (- 1,) }; } | + + help: ...or a vertical bar to match on multiple alternatives | 1 | fn main() { match () { _ => { 1 } - 1 | }; } | ~~~~~ ``` Fixed output after this PR: ```rust fn main() { match () { _ => ({ 1 }) - 1, }; } ``` ## False positives Less problematic, but worth fixing (just like #118726). ```rust fn main() { let _ = match () { _ => 1 } - 1; } ``` Output of `rustc -Zunpretty=expanded lib.rs` before this PR. There is no reason parentheses would need to be inserted there. ```rust fn main() { let _ = (match () { _ => 1, }) - 1; } ``` After this PR: ```rust fn main() { let _ = match () { _ => 1, } - 1; } ``` ## Alternatives considered In this PR I opted to parenthesize only the leading subexpression causing the statement boundary, rather than the entire statement. Example: ```rust macro_rules! m { ($e:expr) => { $e }; } fn main() { m!(loop { break [1]; }[0] - 1); } ``` This PR produces the following pretty-printed contents for fn main: ```rust (loop { break [1]; })[0] - 1; ``` A different equally correct output would be: ```rust (loop { break [1]; }[0] - 1); ``` I chose the one I did because it is the *only* approach used by handwritten code in the standard library and compiler. There are 4 places where parenthesization is being used to prevent a statement boundary, and in all 4, the developer has chosen to parenthesize the smallest subexpression rather than the whole statement:b37d43efd9/compiler/rustc_codegen_cranelift/example/alloc_system.rs (L102)b37d43efd9/compiler/rustc_parse/src/errors.rs (L1021-L1029)b37d43efd9/library/core/src/future/poll_fn.rs (L151)b37d43efd9/library/core/src/ops/range.rs (L824-L828)
This commit is contained in:
bors
commit
89e2160c4c
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@ -1096,14 +1096,22 @@ fn print_stmt(&mut self, st: &ast::Stmt) {
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ast::StmtKind::Item(item) => self.print_item(item),
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ast::StmtKind::Expr(expr) => {
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self.space_if_not_bol();
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self.print_expr_outer_attr_style(expr, false, FixupContext::default());
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self.print_expr_outer_attr_style(
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expr,
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false,
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FixupContext { stmt: true, ..FixupContext::default() },
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);
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if classify::expr_requires_semi_to_be_stmt(expr) {
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self.word(";");
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}
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}
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ast::StmtKind::Semi(expr) => {
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self.space_if_not_bol();
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self.print_expr_outer_attr_style(expr, false, FixupContext::default());
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self.print_expr_outer_attr_style(
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expr,
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false,
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FixupContext { stmt: true, ..FixupContext::default() },
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);
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self.word(";");
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}
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ast::StmtKind::Empty => {
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@ -1155,7 +1163,11 @@ fn print_block_maybe_unclosed(
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ast::StmtKind::Expr(expr) if i == blk.stmts.len() - 1 => {
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self.maybe_print_comment(st.span.lo());
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self.space_if_not_bol();
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self.print_expr_outer_attr_style(expr, false, FixupContext::default());
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self.print_expr_outer_attr_style(
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expr,
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false,
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FixupContext { stmt: true, ..FixupContext::default() },
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);
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self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
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}
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_ => self.print_stmt(st),
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@ -4,6 +4,7 @@
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use itertools::{Itertools, Position};
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use rustc_ast::ptr::P;
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use rustc_ast::token;
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use rustc_ast::util::classify;
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use rustc_ast::util::literal::escape_byte_str_symbol;
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use rustc_ast::util::parser::{self, AssocOp, Fixity};
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use rustc_ast::{self as ast, BlockCheckMode};
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@ -15,6 +16,61 @@
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#[derive(Copy, Clone, Debug)]
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pub(crate) struct FixupContext {
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/// Print expression such that it can be parsed back as a statement
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/// consisting of the original expression.
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///
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/// The effect of this is for binary operators in statement position to set
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/// `leftmost_subexpression_in_stmt` when printing their left-hand operand.
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///
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/// ```ignore (illustrative)
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/// (match x {}) - 1; // match needs parens when LHS of binary operator
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///
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/// match x {}; // not when its own statement
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/// ```
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pub stmt: bool,
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/// This is the difference between:
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///
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/// ```ignore (illustrative)
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/// (match x {}) - 1; // subexpression needs parens
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///
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/// let _ = match x {} - 1; // no parens
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/// ```
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///
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/// There are 3 distinguishable contexts in which `print_expr` might be
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/// called with the expression `$match` as its argument, where `$match`
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/// represents an expression of kind `ExprKind::Match`:
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///
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/// - stmt=false leftmost_subexpression_in_stmt=false
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///
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/// Example: `let _ = $match - 1;`
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///
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/// No parentheses required.
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///
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/// - stmt=false leftmost_subexpression_in_stmt=true
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///
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/// Example: `$match - 1;`
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///
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/// Must parenthesize `($match)`, otherwise parsing back the output as a
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/// statement would terminate the statement after the closing brace of
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/// the match, parsing `-1;` as a separate statement.
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///
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/// - stmt=true leftmost_subexpression_in_stmt=false
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///
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/// Example: `$match;`
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///
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/// No parentheses required.
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pub leftmost_subexpression_in_stmt: bool,
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/// This is the difference between:
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///
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/// ```ignore (illustrative)
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/// if let _ = (Struct {}) {} // needs parens
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///
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/// match () {
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/// () if let _ = Struct {} => {} // no parens
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/// }
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/// ```
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pub parenthesize_exterior_struct_lit: bool,
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}
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@ -22,7 +78,11 @@ pub(crate) struct FixupContext {
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/// in a targetted fashion where needed.
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impl Default for FixupContext {
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fn default() -> Self {
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FixupContext { parenthesize_exterior_struct_lit: false }
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FixupContext {
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stmt: false,
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leftmost_subexpression_in_stmt: false,
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parenthesize_exterior_struct_lit: false,
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}
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}
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}
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@ -76,7 +136,8 @@ fn print_expr_maybe_paren(&mut self, expr: &ast::Expr, prec: i8, fixup: FixupCon
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/// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
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/// `if cond { ... }`.
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fn print_expr_as_cond(&mut self, expr: &ast::Expr) {
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let fixup = FixupContext { parenthesize_exterior_struct_lit: true };
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let fixup =
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FixupContext { parenthesize_exterior_struct_lit: true, ..FixupContext::default() };
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self.print_expr_cond_paren(expr, Self::cond_needs_par(expr), fixup)
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}
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@ -99,26 +160,25 @@ pub(super) fn print_expr_cond_paren(
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&mut self,
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expr: &ast::Expr,
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needs_par: bool,
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fixup: FixupContext,
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mut fixup: FixupContext,
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) {
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if needs_par {
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self.popen();
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// If we are surrounding the whole cond in parentheses, such as:
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//
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// if (return Struct {}) {}
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//
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// then there is no need for parenthesizing the individual struct
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// expressions within. On the other hand if the whole cond is not
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// parenthesized, then print_expr must parenthesize exterior struct
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// literals.
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//
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// if x == (Struct {}) {}
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//
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fixup = FixupContext::default();
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}
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// If we are surrounding the whole cond in parentheses, such as:
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//
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// if (return Struct {}) {}
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//
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// then there is no need for parenthesizing the individual struct
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// expressions within. On the other hand if the whole cond is not
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// parenthesized, then print_expr must parenthesize exterior struct
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// literals.
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//
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// if x == (Struct {}) {}
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//
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let fixup = FixupContext {
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parenthesize_exterior_struct_lit: fixup.parenthesize_exterior_struct_lit && !needs_par,
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};
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self.print_expr(expr, fixup);
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if needs_par {
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@ -234,7 +294,32 @@ fn print_expr_call(&mut self, func: &ast::Expr, args: &[P<ast::Expr>], fixup: Fi
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_ => parser::PREC_POSTFIX,
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};
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self.print_expr_maybe_paren(func, prec, fixup);
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// Independent of parenthesization related to precedence, we must
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// parenthesize `func` if this is a statement context in which without
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// parentheses, a statement boundary would occur inside `func` or
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// immediately after `func`.
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//
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// Suppose `func` represents `match () { _ => f }`. We must produce:
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//
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// (match () { _ => f })();
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//
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// instead of:
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//
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// match () { _ => f } ();
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//
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// because the latter is valid syntax but with the incorrect meaning.
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// It's a match-expression followed by tuple-expression, not a function
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// call.
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self.print_expr_maybe_paren(
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func,
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prec,
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FixupContext {
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stmt: false,
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leftmost_subexpression_in_stmt: fixup.stmt || fixup.leftmost_subexpression_in_stmt,
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..fixup
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},
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);
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self.print_call_post(args)
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}
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@ -245,7 +330,17 @@ fn print_expr_method_call(
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base_args: &[P<ast::Expr>],
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fixup: FixupContext,
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) {
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// Unlike in `print_expr_call`, no change to fixup here because
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// statement boundaries never occur in front of a `.` (or `?`) token.
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//
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// match () { _ => f }.method();
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//
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// Parenthesizing only for precedence and not with regard to statement
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// boundaries, `$receiver.method()` can be parsed back as a statement
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// containing an expression if and only if `$receiver` can be parsed as
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// a statement containing an expression.
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self.print_expr_maybe_paren(receiver, parser::PREC_POSTFIX, fixup);
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self.word(".");
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self.print_ident(segment.ident);
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if let Some(args) = &segment.args {
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|
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@ -289,22 +384,36 @@ fn print_expr_binary(
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(&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
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parser::PREC_FORCE_PAREN
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}
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// For a binary expression like `(match () { _ => a }) OP b`, the parens are required
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// otherwise the parser would interpret `match () { _ => a }` as a statement,
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// with the remaining `OP b` not making sense. So we force parens.
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(&ast::ExprKind::Match(..), _) => parser::PREC_FORCE_PAREN,
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_ => left_prec,
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};
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self.print_expr_maybe_paren(lhs, left_prec, fixup);
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self.print_expr_maybe_paren(
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lhs,
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left_prec,
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FixupContext {
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stmt: false,
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leftmost_subexpression_in_stmt: fixup.stmt || fixup.leftmost_subexpression_in_stmt,
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..fixup
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},
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);
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self.space();
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self.word_space(op.node.as_str());
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self.print_expr_maybe_paren(rhs, right_prec, fixup)
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self.print_expr_maybe_paren(
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rhs,
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right_prec,
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FixupContext { stmt: false, leftmost_subexpression_in_stmt: false, ..fixup },
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);
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}
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fn print_expr_unary(&mut self, op: ast::UnOp, expr: &ast::Expr, fixup: FixupContext) {
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self.word(op.as_str());
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self.print_expr_maybe_paren(expr, parser::PREC_PREFIX, fixup)
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self.print_expr_maybe_paren(
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expr,
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parser::PREC_PREFIX,
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FixupContext { stmt: false, leftmost_subexpression_in_stmt: false, ..fixup },
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);
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}
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fn print_expr_addr_of(
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|
|
@ -322,7 +431,11 @@ fn print_expr_addr_of(
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self.print_mutability(mutability, true);
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}
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}
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self.print_expr_maybe_paren(expr, parser::PREC_PREFIX, fixup)
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self.print_expr_maybe_paren(
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expr,
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parser::PREC_PREFIX,
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FixupContext { stmt: false, leftmost_subexpression_in_stmt: false, ..fixup },
|
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);
|
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}
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pub(super) fn print_expr(&mut self, expr: &ast::Expr, fixup: FixupContext) {
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|
|
@ -333,7 +446,7 @@ pub(super) fn print_expr_outer_attr_style(
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&mut self,
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expr: &ast::Expr,
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is_inline: bool,
|
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fixup: FixupContext,
|
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mut fixup: FixupContext,
|
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) {
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self.maybe_print_comment(expr.span.lo());
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|
|
@ -345,7 +458,27 @@ pub(super) fn print_expr_outer_attr_style(
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}
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self.ibox(INDENT_UNIT);
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// The Match subexpression in `match x {} - 1` must be parenthesized if
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// it is the leftmost subexpression in a statement:
|
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//
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// (match x {}) - 1;
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//
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// But not otherwise:
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//
|
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// let _ = match x {} - 1;
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//
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// Same applies to a small set of other expression kinds which eagerly
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// terminate a statement which opens with them.
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let needs_par =
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fixup.leftmost_subexpression_in_stmt && !classify::expr_requires_semi_to_be_stmt(expr);
|
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if needs_par {
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self.popen();
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fixup = FixupContext::default();
|
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}
|
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|
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self.ann.pre(self, AnnNode::Expr(expr));
|
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|
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match &expr.kind {
|
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ast::ExprKind::Array(exprs) => {
|
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self.print_expr_vec(exprs);
|
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|
|
@ -386,7 +519,16 @@ pub(super) fn print_expr_outer_attr_style(
|
|||
}
|
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ast::ExprKind::Cast(expr, ty) => {
|
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let prec = AssocOp::As.precedence() as i8;
|
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self.print_expr_maybe_paren(expr, prec, fixup);
|
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self.print_expr_maybe_paren(
|
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expr,
|
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prec,
|
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FixupContext {
|
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stmt: false,
|
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leftmost_subexpression_in_stmt: fixup.stmt
|
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|| fixup.leftmost_subexpression_in_stmt,
|
||||
..fixup
|
||||
},
|
||||
);
|
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self.space();
|
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self.word_space("as");
|
||||
self.print_type(ty);
|
||||
|
|
@ -508,31 +650,71 @@ pub(super) fn print_expr_outer_attr_style(
|
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self.print_block_with_attrs(blk, attrs);
|
||||
}
|
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ast::ExprKind::Await(expr, _) => {
|
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// Same fixups as ExprKind::MethodCall.
|
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self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX, fixup);
|
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self.word(".await");
|
||||
}
|
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ast::ExprKind::Assign(lhs, rhs, _) => {
|
||||
// Same fixups as ExprKind::Binary.
|
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let prec = AssocOp::Assign.precedence() as i8;
|
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self.print_expr_maybe_paren(lhs, prec + 1, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
lhs,
|
||||
prec + 1,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: fixup.stmt
|
||||
|| fixup.leftmost_subexpression_in_stmt,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
self.space();
|
||||
self.word_space("=");
|
||||
self.print_expr_maybe_paren(rhs, prec, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
rhs,
|
||||
prec,
|
||||
FixupContext { stmt: false, leftmost_subexpression_in_stmt: false, ..fixup },
|
||||
);
|
||||
}
|
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ast::ExprKind::AssignOp(op, lhs, rhs) => {
|
||||
// Same fixups as ExprKind::Binary.
|
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let prec = AssocOp::Assign.precedence() as i8;
|
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self.print_expr_maybe_paren(lhs, prec + 1, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
lhs,
|
||||
prec + 1,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: fixup.stmt
|
||||
|| fixup.leftmost_subexpression_in_stmt,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
self.space();
|
||||
self.word(op.node.as_str());
|
||||
self.word_space("=");
|
||||
self.print_expr_maybe_paren(rhs, prec, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
rhs,
|
||||
prec,
|
||||
FixupContext { stmt: false, leftmost_subexpression_in_stmt: false, ..fixup },
|
||||
);
|
||||
}
|
||||
ast::ExprKind::Field(expr, ident) => {
|
||||
// Same fixups as ExprKind::MethodCall.
|
||||
self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX, fixup);
|
||||
self.word(".");
|
||||
self.print_ident(*ident);
|
||||
}
|
||||
ast::ExprKind::Index(expr, index, _) => {
|
||||
self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX, fixup);
|
||||
// Same fixups as ExprKind::Call.
|
||||
self.print_expr_maybe_paren(
|
||||
expr,
|
||||
parser::PREC_POSTFIX,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: fixup.stmt
|
||||
|| fixup.leftmost_subexpression_in_stmt,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
self.word("[");
|
||||
self.print_expr(index, FixupContext::default());
|
||||
self.word("]");
|
||||
|
|
@ -544,14 +726,31 @@ pub(super) fn print_expr_outer_attr_style(
|
|||
// a "normal" binop gets parenthesized. (`LOr` is the lowest-precedence binop.)
|
||||
let fake_prec = AssocOp::LOr.precedence() as i8;
|
||||
if let Some(e) = start {
|
||||
self.print_expr_maybe_paren(e, fake_prec, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
e,
|
||||
fake_prec,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: fixup.stmt
|
||||
|| fixup.leftmost_subexpression_in_stmt,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
}
|
||||
match limits {
|
||||
ast::RangeLimits::HalfOpen => self.word(".."),
|
||||
ast::RangeLimits::Closed => self.word("..="),
|
||||
}
|
||||
if let Some(e) = end {
|
||||
self.print_expr_maybe_paren(e, fake_prec, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
e,
|
||||
fake_prec,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: false,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
}
|
||||
}
|
||||
ast::ExprKind::Underscore => self.word("_"),
|
||||
|
|
@ -565,7 +764,15 @@ pub(super) fn print_expr_outer_attr_style(
|
|||
}
|
||||
if let Some(expr) = opt_expr {
|
||||
self.space();
|
||||
self.print_expr_maybe_paren(expr, parser::PREC_JUMP, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
expr,
|
||||
parser::PREC_JUMP,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: false,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
}
|
||||
}
|
||||
ast::ExprKind::Continue(opt_label) => {
|
||||
|
|
@ -579,7 +786,15 @@ pub(super) fn print_expr_outer_attr_style(
|
|||
self.word("return");
|
||||
if let Some(expr) = result {
|
||||
self.word(" ");
|
||||
self.print_expr_maybe_paren(expr, parser::PREC_JUMP, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
expr,
|
||||
parser::PREC_JUMP,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: false,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
}
|
||||
}
|
||||
ast::ExprKind::Yeet(result) => {
|
||||
|
|
@ -588,13 +803,25 @@ pub(super) fn print_expr_outer_attr_style(
|
|||
self.word("yeet");
|
||||
if let Some(expr) = result {
|
||||
self.word(" ");
|
||||
self.print_expr_maybe_paren(expr, parser::PREC_JUMP, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
expr,
|
||||
parser::PREC_JUMP,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: false,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
}
|
||||
}
|
||||
ast::ExprKind::Become(result) => {
|
||||
self.word("become");
|
||||
self.word(" ");
|
||||
self.print_expr_maybe_paren(result, parser::PREC_JUMP, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
result,
|
||||
parser::PREC_JUMP,
|
||||
FixupContext { stmt: false, leftmost_subexpression_in_stmt: false, ..fixup },
|
||||
);
|
||||
}
|
||||
ast::ExprKind::InlineAsm(a) => {
|
||||
// FIXME: This should have its own syntax, distinct from a macro invocation.
|
||||
|
|
@ -644,10 +871,19 @@ pub(super) fn print_expr_outer_attr_style(
|
|||
|
||||
if let Some(expr) = e {
|
||||
self.space();
|
||||
self.print_expr_maybe_paren(expr, parser::PREC_JUMP, fixup);
|
||||
self.print_expr_maybe_paren(
|
||||
expr,
|
||||
parser::PREC_JUMP,
|
||||
FixupContext {
|
||||
stmt: false,
|
||||
leftmost_subexpression_in_stmt: false,
|
||||
..fixup
|
||||
},
|
||||
);
|
||||
}
|
||||
}
|
||||
ast::ExprKind::Try(e) => {
|
||||
// Same fixups as ExprKind::MethodCall.
|
||||
self.print_expr_maybe_paren(e, parser::PREC_POSTFIX, fixup);
|
||||
self.word("?")
|
||||
}
|
||||
|
|
@ -663,7 +899,13 @@ pub(super) fn print_expr_outer_attr_style(
|
|||
self.pclose()
|
||||
}
|
||||
}
|
||||
|
||||
self.ann.post(self, AnnNode::Expr(expr));
|
||||
|
||||
if needs_par {
|
||||
self.pclose();
|
||||
}
|
||||
|
||||
self.end();
|
||||
}
|
||||
|
||||
|
|
@ -704,7 +946,7 @@ fn print_arm(&mut self, arm: &ast::Arm) {
|
|||
}
|
||||
_ => {
|
||||
self.end(); // Close the ibox for the pattern.
|
||||
self.print_expr(body, FixupContext::default());
|
||||
self.print_expr(body, FixupContext { stmt: true, ..FixupContext::default() });
|
||||
self.word(",");
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -204,6 +204,16 @@ macro_rules! c2_if_let {
|
|||
} ],
|
||||
"match self { Ok => 1, Err => 0, }"
|
||||
);
|
||||
macro_rules! c2_match_arm {
|
||||
([ $expr:expr ], $expr_expected:expr, $tokens_expected:expr $(,)?) => {
|
||||
c2!(expr, [ match () { _ => $expr } ], $expr_expected, $tokens_expected);
|
||||
};
|
||||
}
|
||||
c2_match_arm!(
|
||||
[ { 1 } - 1 ],
|
||||
"match () { _ => ({ 1 }) - 1, }",
|
||||
"match() { _ => { 1 } - 1 }",
|
||||
);
|
||||
|
||||
// ExprKind::Closure
|
||||
c1!(expr, [ || {} ], "|| {}");
|
||||
|
|
@ -651,6 +661,16 @@ fn test_stmt() {
|
|||
"let (a, b): (u32, u32) = (1, 2);",
|
||||
"let(a, b): (u32, u32) = (1, 2)" // FIXME
|
||||
);
|
||||
macro_rules! c2_let_expr_minus_one {
|
||||
([ $expr:expr ], $stmt_expected:expr, $tokens_expected:expr $(,)?) => {
|
||||
c2!(stmt, [ let _ = $expr - 1 ], $stmt_expected, $tokens_expected);
|
||||
};
|
||||
}
|
||||
c2_let_expr_minus_one!(
|
||||
[ match void {} ],
|
||||
"let _ = match void {} - 1;",
|
||||
"let _ = match void {} - 1",
|
||||
);
|
||||
|
||||
// StmtKind::Item
|
||||
c1!(stmt, [ struct S; ], "struct S;");
|
||||
|
|
@ -661,6 +681,46 @@ fn test_stmt() {
|
|||
|
||||
// StmtKind::Semi
|
||||
c2!(stmt, [ 1 + 1 ], "1 + 1;", "1 + 1");
|
||||
macro_rules! c2_expr_as_stmt {
|
||||
// Parse as expr, then reparse as stmt.
|
||||
//
|
||||
// The c2_minus_one macro below can't directly call `c2!(stmt, ...)`
|
||||
// because `$expr - 1` cannot be parsed directly as a stmt. A statement
|
||||
// boundary occurs after the `match void {}`, after which the `-` token
|
||||
// hits "no rules expected this token in macro call".
|
||||
//
|
||||
// The unwanted statement boundary is exactly why the pretty-printer is
|
||||
// injecting parentheses around the subexpression, which is the behavior
|
||||
// we are interested in testing.
|
||||
([ $expr:expr ], $stmt_expected:expr, $tokens_expected:expr $(,)?) => {
|
||||
c2!(stmt, [ $expr ], $stmt_expected, $tokens_expected);
|
||||
};
|
||||
}
|
||||
macro_rules! c2_minus_one {
|
||||
([ $expr:expr ], $stmt_expected:expr, $tokens_expected:expr $(,)?) => {
|
||||
c2_expr_as_stmt!([ $expr - 1 ], $stmt_expected, $tokens_expected);
|
||||
};
|
||||
}
|
||||
c2_minus_one!(
|
||||
[ match void {} ],
|
||||
"(match void {}) - 1;",
|
||||
"match void {} - 1",
|
||||
);
|
||||
c2_minus_one!(
|
||||
[ match void {}() ],
|
||||
"(match void {})() - 1;",
|
||||
"match void {}() - 1",
|
||||
);
|
||||
c2_minus_one!(
|
||||
[ match void {}[0] ],
|
||||
"(match void {})[0] - 1;",
|
||||
"match void {}[0] - 1",
|
||||
);
|
||||
c2_minus_one!(
|
||||
[ loop { break 1; } ],
|
||||
"(loop { break 1; }) - 1;",
|
||||
"loop { break 1; } - 1",
|
||||
);
|
||||
|
||||
// StmtKind::Empty
|
||||
c1!(stmt, [ ; ], ";");
|
||||
|
|
|
|||
Loading…
Reference in a new issue