Merge #1101

1101: Parse unsafe async / const unsafe fns properly r=matklad a=robojumper

Also adds tests that `unsafe async fn` as well as `const unsafe fn` parse properly and that these keywords in the reversed order cause parse errors.

[Playground link to verify that this is the correct order.](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=7850b8d92579de31c38f835f76afa4ce)

Closes #1086.


Co-authored-by: robojumper <[email protected]>

2 files changed, 41 insertions, 0 deletions

diff --git a/crates/ra_syntax/tests/data/parser/inline/err/0010_wrong_order_fns.rs b/crates/ra_syntax/tests/data/parser/inline/err/0010_wrong_order_fns.rs
new file mode 100644
index 000000000..16edee95d
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/err/0010_wrong_order_fns.rs
@@ -0,0 +1,2 @@
+async unsafe fn foo() {}
+unsafe const fn bar() {}
diff --git a/crates/ra_syntax/tests/data/parser/inline/err/0010_wrong_order_fns.txt b/crates/ra_syntax/tests/data/parser/inline/err/0010_wrong_order_fns.txt
new file mode 100644
index 000000000..220191ffa
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/err/0010_wrong_order_fns.txt
@@ -0,0 +1,39 @@
+SOURCE_FILE@[0; 50)
+  ERROR@[0; 5)
+    ASYNC_KW@[0; 5) "async"
+    err: `expected fn, trait or impl`
+  WHITESPACE@[5; 6) " "
+  FN_DEF@[6; 24)
+    UNSAFE_KW@[6; 12) "unsafe"
+    WHITESPACE@[12; 13) " "
+    FN_KW@[13; 15) "fn"
+    WHITESPACE@[15; 16) " "
+    NAME@[16; 19)
+      IDENT@[16; 19) "foo"
+    PARAM_LIST@[19; 21)
+      L_PAREN@[19; 20) "("
+      R_PAREN@[20; 21) ")"
+    WHITESPACE@[21; 22) " "
+    BLOCK@[22; 24)
+      L_CURLY@[22; 23) "{"
+      R_CURLY@[23; 24) "}"
+  WHITESPACE@[24; 25) "\n"
+  ERROR@[25; 31)
+    UNSAFE_KW@[25; 31) "unsafe"
+    err: `expected fn, trait or impl`
+  WHITESPACE@[31; 32) " "
+  FN_DEF@[32; 49)
+    CONST_KW@[32; 37) "const"
+    WHITESPACE@[37; 38) " "
+    FN_KW@[38; 40) "fn"
+    WHITESPACE@[40; 41) " "
+    NAME@[41; 44)
+      IDENT@[41; 44) "bar"
+    PARAM_LIST@[44; 46)
+      L_PAREN@[44; 45) "("
+      R_PAREN@[45; 46) ")"
+    WHITESPACE@[46; 47) " "
+    BLOCK@[47; 49)
+      L_CURLY@[47; 48) "{"
+      R_CURLY@[48; 49) "}"
+  WHITESPACE@[49; 50) "\n"