Merge #1951

1951: Lower the precedence of the `as` operator. r=matklad a=goffrie

Previously, the `as` operator was being parsed like a postfix expression, and
therefore being given the highest possible precedence. That caused it to bind
more tightly than prefix operators, which it should not. Instead, parse it
somewhat like a normal binary expression with some special-casing.

Fixes #1851.

Co-authored-by: Geoffry Song <[email protected]>

2 files changed, 46 insertions, 0 deletions

diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0146_as_precedence.rs b/crates/ra_syntax/test_data/parser/inline/ok/0146_as_precedence.rs
new file mode 100644
index 000000000..a06dec1fa
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0146_as_precedence.rs
@@ -0,0 +1,3 @@
+fn foo() {
+    let _ = &1 as *const i32;
+}
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0146_as_precedence.txt b/crates/ra_syntax/test_data/parser/inline/ok/0146_as_precedence.txt
new file mode 100644
index 000000000..9e3767fb7
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0146_as_precedence.txt
@@ -0,0 +1,43 @@
+SOURCE_FILE@[0; 43)
+  FN_DEF@[0; 42)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 6)
+      IDENT@[3; 6) "foo"
+    PARAM_LIST@[6; 8)
+      L_PAREN@[6; 7) "("
+      R_PAREN@[7; 8) ")"
+    WHITESPACE@[8; 9) " "
+    BLOCK_EXPR@[9; 42)
+      BLOCK@[9; 42)
+        L_CURLY@[9; 10) "{"
+        WHITESPACE@[10; 15) "\n    "
+        LET_STMT@[15; 40)
+          LET_KW@[15; 18) "let"
+          WHITESPACE@[18; 19) " "
+          PLACEHOLDER_PAT@[19; 20)
+            UNDERSCORE@[19; 20) "_"
+          WHITESPACE@[20; 21) " "
+          EQ@[21; 22) "="
+          WHITESPACE@[22; 23) " "
+          CAST_EXPR@[23; 39)
+            REF_EXPR@[23; 25)
+              AMP@[23; 24) "&"
+              LITERAL@[24; 25)
+                INT_NUMBER@[24; 25) "1"
+            WHITESPACE@[25; 26) " "
+            AS_KW@[26; 28) "as"
+            WHITESPACE@[28; 29) " "
+            POINTER_TYPE@[29; 39)
+              STAR@[29; 30) "*"
+              CONST_KW@[30; 35) "const"
+              WHITESPACE@[35; 36) " "
+              PATH_TYPE@[36; 39)
+                PATH@[36; 39)
+                  PATH_SEGMENT@[36; 39)
+                    NAME_REF@[36; 39)
+                      IDENT@[36; 39) "i32"
+          SEMI@[39; 40) ";"
+        WHITESPACE@[40; 41) "\n"
+        R_CURLY@[41; 42) "}"
+  WHITESPACE@[42; 43) "\n"