Auto merge of #16770 - roife:fix-issue-16278, r=Veykril

fix: panic when using float numbers without dots in chain calls

Fix #16278.

This PR fixes the panic caused by using floating-point numbers without a dot (such as `1e2`) in chain calls.

-------------

Although this syntax is very odd 🤣, r-a should not panic.

crates/parser/src/shortcuts.rs

@@ -190,7 +190,7 @@ impl Builder<'_, '_> {
 
     fn do_float_split(&mut self, has_pseudo_dot: bool) {
         let text = &self.lexed.range_text(self.pos..self.pos + 1);
-        self.pos += 1;
+
         match text.split_once('.') {
             Some((left, right)) => {
                 assert!(!left.is_empty());
@@ -216,8 +216,22 @@ impl Builder<'_, '_> {
                     self.state = State::PendingExit;
                 }
             }
-            None => unreachable!(),
+            None => {
+                // illegal float literal which doesn't have dot in form (like 1e0)
+                // we should emit an error node here
+                (self.sink)(StrStep::Error { msg: "illegal float literal", pos: self.pos });
+                (self.sink)(StrStep::Enter { kind: SyntaxKind::ERROR });
+                (self.sink)(StrStep::Token { kind: SyntaxKind::FLOAT_NUMBER, text });
+                (self.sink)(StrStep::Exit);
+
+                // move up
+                (self.sink)(StrStep::Exit);
+
+                self.state = if has_pseudo_dot { State::Normal } else { State::PendingExit };
+            }
         }
+
+        self.pos += 1;
     }
 }
 

crates/parser/test_data/parser/err/0054_float_split_scientific_notation.rast

@@ -0,0 +1,88 @@
+SOURCE_FILE
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    TUPLE_FIELD_LIST
+      L_PAREN "("
+      TUPLE_FIELD
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "i32"
+      COMMA ","
+      WHITESPACE " "
+      TUPLE_FIELD
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "i32"
+      R_PAREN ")"
+    SEMICOLON ";"
+  WHITESPACE "\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "f"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "s"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          CALL_EXPR
+            PATH_EXPR
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "S"
+            ARG_LIST
+              L_PAREN "("
+              LITERAL
+                INT_NUMBER "1"
+              COMMA ","
+              WHITESPACE " "
+              LITERAL
+                INT_NUMBER "2"
+              R_PAREN ")"
+          SEMICOLON ";"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "a"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          FIELD_EXPR
+            FIELD_EXPR
+              PATH_EXPR
+                PATH
+                  PATH_SEGMENT
+                    NAME_REF
+                      IDENT "s"
+              DOT "."
+              ERROR
+                FLOAT_NUMBER "1e0"
+          SEMICOLON ";"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 42: illegal float literal

crates/parser/test_data/parser/err/0054_float_split_scientific_notation.rs

@@ -0,0 +1,5 @@
+struct S(i32, i32);
+fn f() {
+    let s = S(1, 2);
+    let a = s.1e0;
+}