Merge #11167

11167: internal: check top level entry point invariants r=matklad a=matklad

bors r+
🤖

Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>

crates/hir_def/src/macro_expansion_tests/mbe/tt_conversion.rs

@@ -105,21 +105,21 @@ macro_rules! m2 { ($x:ident) => {} }
 
 #[test]
 fn expansion_does_not_parse_as_expression() {
-    cov_mark::check!(expansion_does_not_parse_as_expression);
     check(
         r#"
 macro_rules! stmts {
     () => { let _ = 0; }
 }
 
-fn f() { let _ = stmts!(); }
+fn f() { let _ = stmts!/*+errors*/(); }
 "#,
         expect![[r#"
 macro_rules! stmts {
     () => { let _ = 0; }
 }
 
-fn f() { let _ = /* error: could not convert tokens */; }
+fn f() { let _ = /* parse error: expected expression */
+let _ = 0;; }
 "#]],
     )
 }

crates/ide/src/hover/tests.rs

@@ -1148,7 +1148,7 @@ fn foo() { let a = id!([0u32, bar($0)] ); }
 fn test_hover_through_literal_string_in_macro() {
     check(
         r#"
-macro_rules! arr { ($($tt:tt)*) => { [$($tt)*)] } }
+macro_rules! arr { ($($tt:tt)*) => { [$($tt)*] } }
 fn foo() {
     let mastered_for_itunes = "";
     let _ = arr!("Tr$0acks", &mastered_for_itunes);

crates/mbe/src/syntax_bridge.rs

@@ -1,7 +1,7 @@
 //! Conversions between [`SyntaxNode`] and [`tt::TokenTree`].
 
 use rustc_hash::{FxHashMap, FxHashSet};
-use stdx::non_empty_vec::NonEmptyVec;
+use stdx::{never, non_empty_vec::NonEmptyVec};
 use syntax::{
     ast::{self, make::tokens::doc_comment},
     AstToken, Parse, PreorderWithTokens, SmolStr, SyntaxElement, SyntaxKind,
@@ -66,8 +66,7 @@ pub fn token_tree_to_syntax_node(
             parser::Step::Error { msg } => tree_sink.error(msg.to_string()),
         }
     }
-    if tree_sink.roots.len() != 1 {
-        cov_mark::hit!(expansion_does_not_parse_as_expression);
+    if never!(tree_sink.roots.len() != 1) {
         return Err(ExpandError::ConversionError);
     }
     //FIXME: would be cool to report errors

crates/parser/src/grammar.rs

@@ -135,6 +135,32 @@ pub(crate) mod entry {
             }
             m.complete(p, ERROR);
         }
+
+        pub(crate) fn expr(p: &mut Parser) {
+            let m = p.start();
+            expressions::expr(p);
+            if p.at(EOF) {
+                m.abandon(p);
+                return;
+            }
+            while !p.at(EOF) {
+                p.bump_any();
+            }
+            m.complete(p, ERROR);
+        }
+
+        pub(crate) fn meta_item(p: &mut Parser) {
+            let m = p.start();
+            attributes::meta(p);
+            if p.at(EOF) {
+                m.abandon(p);
+                return;
+            }
+            while !p.at(EOF) {
+                p.bump_any();
+            }
+            m.complete(p, ERROR);
+        }
     }
 }
 

crates/parser/src/lib.rs

@@ -41,6 +41,75 @@ pub use crate::{
     syntax_kind::SyntaxKind,
 };
 
+/// Parse the whole of the input as a given syntactic construct.
+///
+/// This covers two main use-cases:
+///
+///   * Parsing a Rust file.
+///   * Parsing a result of macro expansion.
+///
+/// That is, for something like
+///
+/// ```
+/// quick_check! {
+///    fn prop() {}
+/// }
+/// ```
+///
+/// the input to the macro will be parsed with [`PrefixEntryPoint::Item`], and
+/// the result will be [`TopEntryPoint::MacroItems`].
+///
+/// [`TopEntryPoint::parse`] makes a guarantee that
+///   * all input is consumed
+///   * the result is a valid tree (there's one root node)
+#[derive(Debug)]
+pub enum TopEntryPoint {
+    SourceFile,
+    MacroStmts,
+    MacroItems,
+    Pattern,
+    Type,
+    Expr,
+    /// Edge case -- macros generally don't expand to attributes, with the
+    /// exception of `cfg_attr` which does!
+    MetaItem,
+}
+
+impl TopEntryPoint {
+    pub fn parse(&self, input: &Input) -> Output {
+        let entry_point: fn(&'_ mut parser::Parser) = match self {
+            TopEntryPoint::SourceFile => grammar::entry::top::source_file,
+            TopEntryPoint::MacroStmts => grammar::entry::top::macro_stmts,
+            TopEntryPoint::MacroItems => grammar::entry::top::macro_items,
+            TopEntryPoint::Pattern => grammar::entry::top::pattern,
+            TopEntryPoint::Type => grammar::entry::top::type_,
+            TopEntryPoint::Expr => grammar::entry::top::expr,
+            TopEntryPoint::MetaItem => grammar::entry::top::meta_item,
+        };
+        let mut p = parser::Parser::new(input);
+        entry_point(&mut p);
+        let events = p.finish();
+        let res = event::process(events);
+
+        if cfg!(debug_assertions) {
+            let mut depth = 0;
+            let mut first = true;
+            for step in res.iter() {
+                assert!(depth > 0 || first);
+                first = false;
+                match step {
+                    Step::Enter { .. } => depth += 1,
+                    Step::Exit => depth -= 1,
+                    Step::Token { .. } | Step::Error { .. } => (),
+                }
+            }
+            assert!(!first, "no tree at all");
+        }
+
+        res
+    }
+}
+
 /// Parse a prefix of the input as a given syntactic construct.
 ///
 /// This is used by macro-by-example parser to implement things like `$i:item`
@@ -83,57 +152,6 @@ impl PrefixEntryPoint {
     }
 }
 
-/// Parse the whole of the input as a given syntactic construct.
-///
-/// This covers two main use-cases:
-///
-///   * Parsing a Rust file.
-///   * Parsing a result of macro expansion.
-///
-/// That is, for something like
-///
-/// ```
-/// quick_check! {
-///    fn prop() {}
-/// }
-/// ```
-///
-/// the input to the macro will be parsed with [`PrefixEntryPoint::Item`], and
-/// the result will be [`TopEntryPoint::Items`].
-///
-/// This *should* (but currently doesn't) guarantee that all input is consumed.
-#[derive(Debug)]
-pub enum TopEntryPoint {
-    SourceFile,
-    MacroStmts,
-    MacroItems,
-    Pattern,
-    Type,
-    Expr,
-    /// Edge case -- macros generally don't expand to attributes, with the
-    /// exception of `cfg_attr` which does!
-    MetaItem,
-}
-
-impl TopEntryPoint {
-    pub fn parse(&self, input: &Input) -> Output {
-        let entry_point: fn(&'_ mut parser::Parser) = match self {
-            TopEntryPoint::SourceFile => grammar::entry::top::source_file,
-            TopEntryPoint::MacroStmts => grammar::entry::top::macro_stmts,
-            TopEntryPoint::MacroItems => grammar::entry::top::macro_items,
-            TopEntryPoint::Pattern => grammar::entry::top::pattern,
-            TopEntryPoint::Type => grammar::entry::top::type_,
-            // FIXME
-            TopEntryPoint::Expr => grammar::entry::prefix::expr,
-            TopEntryPoint::MetaItem => grammar::entry::prefix::meta_item,
-        };
-        let mut p = parser::Parser::new(input);
-        entry_point(&mut p);
-        let events = p.finish();
-        event::process(events)
-    }
-}
-
 /// A parsing function for a specific braced-block.
 pub struct Reparser(fn(&mut parser::Parser));
 

crates/parser/src/tests.rs

@@ -1,6 +1,6 @@
 mod sourcegen_inline_tests;
-mod prefix_entries;
 mod top_entries;
+mod prefix_entries;
 
 use std::{
     fmt::Write,

crates/parser/src/tests/top_entries.rs

@@ -51,6 +51,13 @@ fn source_file() {
 
 #[test]
 fn macro_stmt() {
+    check(
+        TopEntryPoint::MacroStmts,
+        "",
+        expect![[r#"
+            MACRO_STMTS
+        "#]],
+    );
     check(
         TopEntryPoint::MacroStmts,
         "#!/usr/bin/rust",
@@ -94,6 +101,13 @@ fn macro_stmt() {
 
 #[test]
 fn macro_items() {
+    check(
+        TopEntryPoint::MacroItems,
+        "",
+        expect![[r#"
+            MACRO_ITEMS
+        "#]],
+    );
     check(
         TopEntryPoint::MacroItems,
         "#!/usr/bin/rust",
@@ -131,6 +145,14 @@ fn macro_items() {
 
 #[test]
 fn macro_pattern() {
+    check(
+        TopEntryPoint::Pattern,
+        "",
+        expect![[r#"
+            ERROR
+            error 0: expected pattern
+        "#]],
+    );
     check(
         TopEntryPoint::Pattern,
         "Some(_)",
@@ -177,6 +199,15 @@ fn macro_pattern() {
 
 #[test]
 fn type_() {
+    check(
+        TopEntryPoint::Type,
+        "",
+        expect![[r#"
+            ERROR
+            error 0: expected type
+        "#]],
+    );
+
     check(
         TopEntryPoint::Type,
         "Option<!>",
@@ -224,6 +255,54 @@ fn type_() {
     );
 }
 
+#[test]
+fn expr() {
+    check(
+        TopEntryPoint::Expr,
+        "",
+        expect![[r#"
+            ERROR
+            error 0: expected expression
+        "#]],
+    );
+    check(
+        TopEntryPoint::Expr,
+        "2 + 2 == 5",
+        expect![[r#"
+        BIN_EXPR
+          BIN_EXPR
+            LITERAL
+              INT_NUMBER "2"
+            WHITESPACE " "
+            PLUS "+"
+            WHITESPACE " "
+            LITERAL
+              INT_NUMBER "2"
+          WHITESPACE " "
+          EQ2 "=="
+          WHITESPACE " "
+          LITERAL
+            INT_NUMBER "5"
+    "#]],
+    );
+    check(
+        TopEntryPoint::Expr,
+        "let _ = 0;",
+        expect![[r#"
+        ERROR
+          LET_KW "let"
+          WHITESPACE " "
+          UNDERSCORE "_"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          INT_NUMBER "0"
+          SEMICOLON ";"
+        error 0: expected expression
+    "#]],
+    );
+}
+
 #[track_caller]
 fn check(entry: TopEntryPoint, input: &str, expect: expect_test::Expect) {
     let (parsed, _errors) = super::parse(entry, input);