Mark expr_requires_semi_to_be_stmt call sites

For each of these, we need to decide whether they need to be using
`expr_requires_semi_to_be_stmt`, or `expr_requires_comma_to_be_match_arm`,
which are supposed to be 2 different behaviors. Previously they were
conflated into one, causing either too much or too little
parenthesization.

Author: dtolnay

compiler/rustc_ast/src/util/classify.rs

@@ -42,7 +42,8 @@ use crate::{ast, token::Delimiter};
 ///     _ => m! {} - 1,  // binary subtraction operator
 /// }
 /// ```
-pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool {
+#[allow(non_snake_case)]
+pub fn expr_requires_semi_to_be_stmt_FIXME(e: &ast::Expr) -> bool {
     !matches!(
         e.kind,
         ast::ExprKind::If(..)

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1253,7 +1253,7 @@ impl<'a> State<'a> {
             ast::StmtKind::Expr(expr) => {
                 self.space_if_not_bol();
                 self.print_expr_outer_attr_style(expr, false, FixupContext::new_stmt());
-                if classify::expr_requires_semi_to_be_stmt(expr) {
+                if classify::expr_requires_semi_to_be_stmt_FIXME(expr) {
                     self.word(";");
                 }
             }

compiler/rustc_ast_pretty/src/pprust/state/fixup.rs

@@ -128,7 +128,7 @@ impl FixupContext {
     /// The documentation on `FixupContext::leftmost_subexpression_in_stmt` has
     /// examples.
     pub fn would_cause_statement_boundary(self, expr: &Expr) -> bool {
-        self.leftmost_subexpression_in_stmt && !classify::expr_requires_semi_to_be_stmt(expr)
+        self.leftmost_subexpression_in_stmt && !classify::expr_requires_semi_to_be_stmt_FIXME(expr)
     }
 
     /// Determine whether parentheses are needed around the given `let`

compiler/rustc_lint/src/unused.rs

@@ -688,7 +688,7 @@ trait UnusedDelimLint {
                     ExprKind::Index(base, _subscript, _) => base,
                     _ => break,
                 };
-                if !classify::expr_requires_semi_to_be_stmt(innermost) {
+                if !classify::expr_requires_semi_to_be_stmt_FIXME(innermost) {
                     return true;
                 }
             }

compiler/rustc_parse/src/parser/expr.rs

@@ -498,7 +498,7 @@ impl<'a> Parser<'a> {
     /// Checks if this expression is a successfully parsed statement.
     fn expr_is_complete(&self, e: &Expr) -> bool {
         self.restrictions.contains(Restrictions::STMT_EXPR)
-            && !classify::expr_requires_semi_to_be_stmt(e)
+            && !classify::expr_requires_semi_to_be_stmt_FIXME(e)
     }
 
     /// Parses `x..y`, `x..=y`, and `x..`/`x..=`.
@@ -2694,7 +2694,7 @@ impl<'a> Parser<'a> {
                 // If it's not a free-standing expression, and is followed by a block,
                 // then it's very likely the condition to an `else if`.
                     if self.check(&TokenKind::OpenDelim(Delimiter::Brace))
-                        && classify::expr_requires_semi_to_be_stmt(&cond) =>
+                        && classify::expr_requires_semi_to_be_stmt_FIXME(&cond) =>
                 {
                     self.dcx().emit_err(errors::ExpectedElseBlock {
                         first_tok_span,
@@ -3136,7 +3136,7 @@ impl<'a> Parser<'a> {
                         err
                     })?;
 
-                let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
+                let require_comma = classify::expr_requires_semi_to_be_stmt_FIXME(&expr)
                     && this.token != token::CloseDelim(Delimiter::Brace);
 
                 if !require_comma {

compiler/rustc_parse/src/parser/stmt.rs

@@ -648,7 +648,7 @@ impl<'a> Parser<'a> {
         match &mut stmt.kind {
             // Expression without semicolon.
             StmtKind::Expr(expr)
-                if classify::expr_requires_semi_to_be_stmt(expr)
+                if classify::expr_requires_semi_to_be_stmt_FIXME(expr)
                     && !expr.attrs.is_empty()
                     && ![token::Eof, token::Semi, token::CloseDelim(Delimiter::Brace)]
                         .contains(&self.token.kind) =>
@@ -662,7 +662,8 @@ impl<'a> Parser<'a> {
 
             // Expression without semicolon.
             StmtKind::Expr(expr)
-                if self.token != token::Eof && classify::expr_requires_semi_to_be_stmt(expr) =>
+                if self.token != token::Eof
+                    && classify::expr_requires_semi_to_be_stmt_FIXME(expr) =>
             {
                 // Just check for errors and recover; do not eat semicolon yet.