[Parser] Check for postfix operator in import paths

Add diagnostic and remove operator from path
Fixes rdar://87159294

Author: angela-laar

include/swift/AST/DiagnosticsParse.def

@@ -1616,6 +1616,8 @@ ERROR(attr_private_import_expected_sourcefile_name,none,
       "expected a source file name in @_private(sourceFile:)", ())
 ERROR(attr_private_import_expected_colon,none,
       "expected ':' after @_private(sourceFile", ())
+ERROR(operator_in_import_path,none,
+      "Cannot include postfix operator in import declaration.",())
 
 // opened
 ERROR(opened_attribute_expected_lparen,none,

lib/Parse/ParseDecl.cpp

@@ -4873,6 +4873,11 @@ ParserResult<ImportDecl> Parser::parseDeclImport(ParseDeclOptions Flags,
                            /*diagnoseDollarPrefix=*/false,
                            diag::expected_identifier_in_decl, "import"))
       return nullptr;
+    if (Tok.is(tok::oper_postfix)) {
+        diagnose(Tok, diag::operator_in_import_path)
+          .fixItRemove(Tok.getLoc());
+        return nullptr;
+    }
     HasNext = consumeIf(tok::period);
   } while (HasNext);
 

lib/Parse/Parser.cpp

@@ -951,6 +951,7 @@ bool Parser::parseAnyIdentifier(Identifier &Result, SourceLoc &Loc,
     return false;
   }
 
+
   // When we know we're supposed to get an identifier or operator, map the
   // postfix '!' to an operator name.
   if (Tok.is(tok::exclaim_postfix)) {

test/decl/import/import.swift

@@ -49,6 +49,7 @@ import func Swift.min
 
 import var x // expected-error {{expected module name}}
 import struct Swift.nonexistent // expected-error {{struct 'nonexistent' does not exist in module 'Swift'}}
+import func SwiftUI.Text.++ // expected-error{{Cannot include postfix operator in import declaration.}}{{25-28=}}
 
 import Swift.import.abc // expected-error {{expected identifier in import declaration}}
 // expected-error @-1 {{keyword 'import' cannot be used as an identifier here}}