Fix parsing of "postfix" range expressions.

Right now they are handled in `postfix_dot_expr`, but that doesn't allow it to
correctly handle precedence. Integrate it more tightly with the Pratt parser
instead.

Also includes a drive-by fix for parsing `match .. {}`.

Fixes #2242.

7 files changed, 142 insertions, 30 deletions

diff --git a/crates/ra_parser/src/grammar/expressions.rs b/crates/ra_parser/src/grammar/expressions.rs
index 45f2e3de4..cf69da25a 100644
--- a/crates/ra_parser/src/grammar/expressions.rs
+++ b/crates/ra_parser/src/grammar/expressions.rs
@@ -290,6 +290,25 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>,
         let m = lhs.precede(p);
         p.bump(op);
 
+        if is_range {
+            // test postfix_range
+            // fn foo() {
+            //     let x = 1..;
+            //     match 1.. { _ => () };
+            //     match a.b()..S { _ => () };
+            // }
+            let has_trailing_expression =
+                p.at_ts(EXPR_FIRST) && !(r.forbid_structs && p.at(T!['{']));
+            if !has_trailing_expression {
+                if op == T![..=] {
+                    p.error("expected expression to end inclusive range");
+                }
+                // no RHS
+                lhs = m.complete(p, RANGE_EXPR);
+                break;
+            }
+        }
+
         expr_bp(p, r, op_bp + 1);
         lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
     }
@@ -330,7 +349,7 @@ fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)>
                 if p.at(op) {
                     m = p.start();
                     p.bump(op);
-                    if p.at_ts(EXPR_FIRST) {
+                    if p.at_ts(EXPR_FIRST) && !(r.forbid_structs && p.at(T!['{'])) {
                         expr_bp(p, r, 2);
                     }
                     return Some((m.complete(p, RANGE_EXPR), BlockLike::NotBlock));
@@ -344,13 +363,7 @@ fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)>
             // }
             //
             let (lhs, blocklike) = atom::atom_expr(p, r)?;
-            return Some(postfix_expr(
-                p,
-                lhs,
-                blocklike,
-                !(r.prefer_stmt && blocklike.is_block()),
-                r.forbid_structs,
-            ));
+            return Some(postfix_expr(p, lhs, blocklike, !(r.prefer_stmt && blocklike.is_block())));
         }
     };
     // parse the interior of the unary expression
@@ -366,7 +379,6 @@ fn postfix_expr(
     // `while true {break}; ();`
     mut block_like: BlockLike,
     mut allow_calls: bool,
-    forbid_structs: bool,
 ) -> (CompletedMarker, BlockLike) {
     loop {
         lhs = match p.current() {
@@ -380,7 +392,7 @@ fn postfix_expr(
             // }
             T!['('] if allow_calls => call_expr(p, lhs),
             T!['['] if allow_calls => index_expr(p, lhs),
-            T![.] => match postfix_dot_expr(p, lhs, forbid_structs) {
+            T![.] => match postfix_dot_expr(p, lhs) {
                 Ok(it) => it,
                 Err(it) => {
                     lhs = it;
@@ -398,7 +410,6 @@ fn postfix_expr(
     fn postfix_dot_expr(
         p: &mut Parser,
         lhs: CompletedMarker,
-        forbid_structs: bool,
     ) -> Result<CompletedMarker, CompletedMarker> {
         assert!(p.at(T![.]));
         if p.nth(1) == IDENT && (p.nth(2) == T!['('] || p.nth_at(2, T![::])) {
@@ -418,25 +429,8 @@ fn postfix_expr(
             return Ok(m.complete(p, AWAIT_EXPR));
         }
 
-        // test postfix_range
-        // fn foo() {
-        //     let x = 1..;
-        //     match 1.. { _ => () };
-        //     match a.b()..S { _ => () };
-        // }
-        for &(op, la) in &[(T![..=], 3), (T![..], 2)] {
-            if p.at(op) {
-                let next_token = p.nth(la);
-                let has_trailing_expression =
-                    !(forbid_structs && next_token == T!['{']) && EXPR_FIRST.contains(next_token);
-                return if has_trailing_expression {
-                    Err(lhs)
-                } else {
-                    let m = lhs.precede(p);
-                    p.bump(op);
-                    Ok(m.complete(p, RANGE_EXPR))
-                };
-            }
+        if p.at(T![..=]) || p.at(T![..]) {
+            return Err(lhs);
         }
 
         Ok(field_expr(p, lhs))
diff --git a/crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.rs b/crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.rs
new file mode 100644
index 000000000..ecd25afaf
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.rs
@@ -0,0 +1,3 @@
+fn main() {
+    0..=;
+}
diff --git a/crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.txt b/crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.txt
new file mode 100644
index 000000000..3efe98164
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.txt
@@ -0,0 +1,24 @@
+SOURCE_FILE@[0; 24)
+  FN_DEF@[0; 23)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 7)
+      IDENT@[3; 7) "main"
+    PARAM_LIST@[7; 9)
+      L_PAREN@[7; 8) "("
+      R_PAREN@[8; 9) ")"
+    WHITESPACE@[9; 10) " "
+    BLOCK_EXPR@[10; 23)
+      BLOCK@[10; 23)
+        L_CURLY@[10; 11) "{"
+        WHITESPACE@[11; 16) "\n    "
+        EXPR_STMT@[16; 21)
+          RANGE_EXPR@[16; 20)
+            LITERAL@[16; 17)
+              INT_NUMBER@[16; 17) "0"
+            DOTDOTEQ@[17; 20) "..="
+          SEMI@[20; 21) ";"
+        WHITESPACE@[21; 22) "\n"
+        R_CURLY@[22; 23) "}"
+  WHITESPACE@[23; 24) "\n"
+error 20: expected expression to end inclusive range
diff --git a/crates/ra_syntax/test_data/parser/ok/0060_as_range.rs b/crates/ra_syntax/test_data/parser/ok/0060_as_range.rs
new file mode 100644
index 000000000..f063ffadb
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0060_as_range.rs
@@ -0,0 +1,4 @@
+fn main() {
+    0 as usize ..;
+    1 + 2 as usize ..;
+}
diff --git a/crates/ra_syntax/test_data/parser/ok/0060_as_range.txt b/crates/ra_syntax/test_data/parser/ok/0060_as_range.txt
new file mode 100644
index 000000000..ad0c4a3fe
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0060_as_range.txt
@@ -0,0 +1,56 @@
+SOURCE_FILE@[0; 56)
+  FN_DEF@[0; 55)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 7)
+      IDENT@[3; 7) "main"
+    PARAM_LIST@[7; 9)
+      L_PAREN@[7; 8) "("
+      R_PAREN@[8; 9) ")"
+    WHITESPACE@[9; 10) " "
+    BLOCK_EXPR@[10; 55)
+      BLOCK@[10; 55)
+        L_CURLY@[10; 11) "{"
+        WHITESPACE@[11; 16) "\n    "
+        EXPR_STMT@[16; 30)
+          RANGE_EXPR@[16; 29)
+            CAST_EXPR@[16; 26)
+              LITERAL@[16; 17)
+                INT_NUMBER@[16; 17) "0"
+              WHITESPACE@[17; 18) " "
+              AS_KW@[18; 20) "as"
+              WHITESPACE@[20; 21) " "
+              PATH_TYPE@[21; 26)
+                PATH@[21; 26)
+                  PATH_SEGMENT@[21; 26)
+                    NAME_REF@[21; 26)
+                      IDENT@[21; 26) "usize"
+            WHITESPACE@[26; 27) " "
+            DOTDOT@[27; 29) ".."
+          SEMI@[29; 30) ";"
+        WHITESPACE@[30; 35) "\n    "
+        EXPR_STMT@[35; 53)
+          RANGE_EXPR@[35; 52)
+            BIN_EXPR@[35; 49)
+              LITERAL@[35; 36)
+                INT_NUMBER@[35; 36) "1"
+              WHITESPACE@[36; 37) " "
+              PLUS@[37; 38) "+"
+              WHITESPACE@[38; 39) " "
+              CAST_EXPR@[39; 49)
+                LITERAL@[39; 40)
+                  INT_NUMBER@[39; 40) "2"
+                WHITESPACE@[40; 41) " "
+                AS_KW@[41; 43) "as"
+                WHITESPACE@[43; 44) " "
+                PATH_TYPE@[44; 49)
+                  PATH@[44; 49)
+                    PATH_SEGMENT@[44; 49)
+                      NAME_REF@[44; 49)
+                        IDENT@[44; 49) "usize"
+            WHITESPACE@[49; 50) " "
+            DOTDOT@[50; 52) ".."
+          SEMI@[52; 53) ";"
+        WHITESPACE@[53; 54) "\n"
+        R_CURLY@[54; 55) "}"
+  WHITESPACE@[55; 56) "\n"
diff --git a/crates/ra_syntax/test_data/parser/ok/0061_match_full_range.rs b/crates/ra_syntax/test_data/parser/ok/0061_match_full_range.rs
new file mode 100644
index 000000000..2c4ed11e1
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0061_match_full_range.rs
@@ -0,0 +1,4 @@
+fn main() {
+    match .. {
+    }
+}
diff --git a/crates/ra_syntax/test_data/parser/ok/0061_match_full_range.txt b/crates/ra_syntax/test_data/parser/ok/0061_match_full_range.txt
new file mode 100644
index 000000000..bdfac9b76
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0061_match_full_range.txt
@@ -0,0 +1,27 @@
+SOURCE_FILE@[0; 35)
+  FN_DEF@[0; 34)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 7)
+      IDENT@[3; 7) "main"
+    PARAM_LIST@[7; 9)
+      L_PAREN@[7; 8) "("
+      R_PAREN@[8; 9) ")"
+    WHITESPACE@[9; 10) " "
+    BLOCK_EXPR@[10; 34)
+      BLOCK@[10; 34)
+        L_CURLY@[10; 11) "{"
+        WHITESPACE@[11; 16) "\n    "
+        MATCH_EXPR@[16; 32)
+          MATCH_KW@[16; 21) "match"
+          WHITESPACE@[21; 22) " "
+          RANGE_EXPR@[22; 24)
+            DOTDOT@[22; 24) ".."
+          WHITESPACE@[24; 25) " "
+          MATCH_ARM_LIST@[25; 32)
+            L_CURLY@[25; 26) "{"
+            WHITESPACE@[26; 31) "\n    "
+            R_CURLY@[31; 32) "}"
+        WHITESPACE@[32; 33) "\n"
+        R_CURLY@[33; 34) "}"
+  WHITESPACE@[34; 35) "\n"