Merge #592

592: Allow types to the left of `:` in where predicates r=matklad a=regiontog

Adresses #584 

Co-authored-by: Erlend Tobiassen <[email protected]>

5 files changed, 91 insertions, 37 deletions

diff --git a/crates/ra_syntax/src/grammar/type_params.rs b/crates/ra_syntax/src/grammar/type_params.rs
index 7db25beba..1ec813b3e 100644
--- a/crates/ra_syntax/src/grammar/type_params.rs
+++ b/crates/ra_syntax/src/grammar/type_params.rs
@@ -104,22 +104,36 @@ pub(super) fn opt_where_clause(p: &mut Parser) {
     }
     let m = p.start();
     p.bump();
-    loop {
-        if !(paths::is_path_start(p)
-            || p.current() == LIFETIME
-            || p.current() == FOR_KW
-            || p.current() == L_ANGLE)
-        {
+
+    while is_where_predicate(p) {
+        where_predicate(p);
+
+        let comma = p.eat(COMMA);
+
+        if is_where_clause_end(p) {
             break;
         }
-        where_predicate(p);
-        if p.current() != L_CURLY && p.current() != SEMI && p.current() != EQ {
-            p.expect(COMMA);
+
+        if !comma {
+            p.error("expected comma");
         }
     }
+
     m.complete(p, WHERE_CLAUSE);
 }
 
+fn is_where_predicate(p: &mut Parser) -> bool {
+    match p.current() {
+        LIFETIME => true,
+        IMPL_KW => false,
+        token => types::TYPE_FIRST.contains(token),
+    }
+}
+
+fn is_where_clause_end(p: &mut Parser) -> bool {
+    p.current() == L_CURLY || p.current() == SEMI || p.current() == EQ
+}
+
 fn where_predicate(p: &mut Parser) {
     let m = p.start();
     match p.current() {
@@ -131,20 +145,17 @@ fn where_predicate(p: &mut Parser) {
                 p.error("expected colon");
             }
         }
+        IMPL_KW => {
+            p.error("expected lifetime or type");
+        }
         _ => {
             // test where_pred_for
             // fn test<F>()
             // where
             //    for<'a> F: Fn(&'a str)
             // { }
-            if p.at(FOR_KW) {
-                types::for_binder(p);
-            }
-            if paths::is_path_start(p) || p.at(L_ANGLE) {
-                types::path_type_(p, false);
-            } else {
-                p.error("expected a type");
-            }
+            types::type_(p);
+
             if p.at(COLON) {
                 bounds(p);
             } else {
diff --git a/crates/ra_syntax/tests/data/parser/err/0027_incomplere_where_for.txt b/crates/ra_syntax/tests/data/parser/err/0027_incomplere_where_for.txt
index 694295a60..8a2a73b9b 100644
--- a/crates/ra_syntax/tests/data/parser/err/0027_incomplere_where_for.txt
+++ b/crates/ra_syntax/tests/data/parser/err/0027_incomplere_where_for.txt
@@ -12,14 +12,15 @@ SOURCE_FILE@[0; 30)
       WHERE_KW@[13; 18)
       WHITESPACE@[18; 19)
       WHERE_PRED@[19; 26)
-        FOR_KW@[19; 22)
-        TYPE_PARAM_LIST@[22; 26)
-          L_ANGLE@[22; 23)
-          LIFETIME_PARAM@[23; 25)
-            LIFETIME@[23; 25) "'a"
-          R_ANGLE@[25; 26)
-          err: `expected a type`
-          err: `expected colon`
+        FOR_TYPE@[19; 26)
+          FOR_KW@[19; 22)
+          TYPE_PARAM_LIST@[22; 26)
+            L_ANGLE@[22; 23)
+            LIFETIME_PARAM@[23; 25)
+              LIFETIME@[23; 25) "'a"
+            R_ANGLE@[25; 26)
+            err: `expected a path`
+            err: `expected colon`
     WHITESPACE@[26; 27)
     BLOCK@[27; 29)
       L_CURLY@[27; 28)
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0003_where_pred_for.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0003_where_pred_for.txt
index 921bdacf4..41420ea92 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0003_where_pred_for.txt
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0003_where_pred_for.txt
@@ -18,18 +18,19 @@ SOURCE_FILE@[0; 49)
       WHERE_KW@[13; 18)
       WHITESPACE@[18; 22)
       WHERE_PRED@[22; 44)
-        FOR_KW@[22; 25)
-        TYPE_PARAM_LIST@[25; 29)
-          L_ANGLE@[25; 26)
-          LIFETIME_PARAM@[26; 28)
-            LIFETIME@[26; 28) "'a"
-          R_ANGLE@[28; 29)
-        WHITESPACE@[29; 30)
-        PATH_TYPE@[30; 31)
-          PATH@[30; 31)
-            PATH_SEGMENT@[30; 31)
-              NAME_REF@[30; 31)
-                IDENT@[30; 31) "F"
+        FOR_TYPE@[22; 31)
+          FOR_KW@[22; 25)
+          TYPE_PARAM_LIST@[25; 29)
+            L_ANGLE@[25; 26)
+            LIFETIME_PARAM@[26; 28)
+              LIFETIME@[26; 28) "'a"
+            R_ANGLE@[28; 29)
+          WHITESPACE@[29; 30)
+          PATH_TYPE@[30; 31)
+            PATH@[30; 31)
+              PATH_SEGMENT@[30; 31)
+                NAME_REF@[30; 31)
+                  IDENT@[30; 31) "F"
         COLON@[31; 32)
         WHITESPACE@[32; 33)
         PATH_TYPE@[33; 44)
diff --git a/crates/ra_syntax/tests/data/parser/ok/0038_where_pred_type.rs b/crates/ra_syntax/tests/data/parser/ok/0038_where_pred_type.rs
new file mode 100644
index 000000000..8bfc341a5
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/ok/0038_where_pred_type.rs
@@ -0,0 +1 @@
+fn test() where (u64, u64): Foo {}
\ No newline at end of file
diff --git a/crates/ra_syntax/tests/data/parser/ok/0038_where_pred_type.txt b/crates/ra_syntax/tests/data/parser/ok/0038_where_pred_type.txt
new file mode 100644
index 000000000..4842e9b90
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/ok/0038_where_pred_type.txt
@@ -0,0 +1,40 @@
+SOURCE_FILE@[0; 34)
+  FN_DEF@[0; 34)
+    FN_KW@[0; 2)
+    WHITESPACE@[2; 3)
+    NAME@[3; 7)
+      IDENT@[3; 7) "test"
+    PARAM_LIST@[7; 9)
+      L_PAREN@[7; 8)
+      R_PAREN@[8; 9)
+    WHITESPACE@[9; 10)
+    WHERE_CLAUSE@[10; 31)
+      WHERE_KW@[10; 15)
+      WHITESPACE@[15; 16)
+      WHERE_PRED@[16; 31)
+        TUPLE_TYPE@[16; 26)
+          L_PAREN@[16; 17)
+          PATH_TYPE@[17; 20)
+            PATH@[17; 20)
+              PATH_SEGMENT@[17; 20)
+                NAME_REF@[17; 20)
+                  IDENT@[17; 20) "u64"
+          COMMA@[20; 21)
+          WHITESPACE@[21; 22)
+          PATH_TYPE@[22; 25)
+            PATH@[22; 25)
+              PATH_SEGMENT@[22; 25)
+                NAME_REF@[22; 25)
+                  IDENT@[22; 25) "u64"
+          R_PAREN@[25; 26)
+        COLON@[26; 27)
+        WHITESPACE@[27; 28)
+        PATH_TYPE@[28; 31)
+          PATH@[28; 31)
+            PATH_SEGMENT@[28; 31)
+              NAME_REF@[28; 31)
+                IDENT@[28; 31) "Foo"
+    WHITESPACE@[31; 32)
+    BLOCK@[32; 34)
+      L_CURLY@[32; 33)
+      R_CURLY@[33; 34)