Merge pull request swiftlang#31073 from rintaro/ide-completion-analyzetuple-rdar61668779

[CodeCompletion] Fix a crash in context type analysis for tuple expr

Author: rintaro

lib/IDE/ExprContextAnalysis.cpp

@@ -762,7 +762,9 @@ class ExprContextAnalyzer {
       unsigned Position = 0;
       bool HasName;
       if (getPositionInArgs(*DC, Parent, ParsedExpr, Position, HasName)) {
-        recordPossibleType(tupleT->getElementType(Position));
+        // The expected type may have fewer number of elements.
+        if (Position < tupleT->getNumElements())
+          recordPossibleType(tupleT->getElementType(Position));
       }
       break;
     }

test/IDE/complete_call_arg.swift

@@ -101,6 +101,8 @@
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=ARG_PARAMFLAG_IUO | %FileCheck %s -check-prefix=ARG_PARAMFLAG_IUO
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=ARG_PARAMFLAG_VARIADIC | %FileCheck %s -check-prefix=ARG_PARAMFLAG_VARIADIC
 
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=TUPLEELEM_1 | %FileCheck %s -check-prefix=TUPLEELEM_1
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=TUPLEELEM_2 | %FileCheck %s -check-prefix=TUPLEELEM_2
 
 var i1 = 1
 var i2 = 2
@@ -816,3 +818,14 @@ func testPamrameterFlags(_: Int, inoutArg: inout Int, autoclosureArg: @autoclosu
 // ARG_PARAMFLAG_VARIADIC-DAG: Pattern/ExprSpecific: {#variadicArg: Int...#}[#Int#];
 // ARG_PARAMFLAG_VARIADIC: End completions
 }
+
+func testTupleElement(arg: (SimpleEnum, SimpleEnum)) {
+  testTupleElement(arg: (.foo, .#^TUPLEELEM_1^#))
+// TUPLEELEM_1: Begin completions, 3 items
+// TUPLEELEM_1-DAG: Decl[EnumElement]/ExprSpecific/TypeRelation[Identical]:     foo[#SimpleEnum#]; name=foo
+// TUPLEELEM_1-DAG: Decl[EnumElement]/ExprSpecific/TypeRelation[Identical]:     bar[#SimpleEnum#]; name=bar
+// TUPLEELEM_1-DAG: Decl[EnumElement]/ExprSpecific/TypeRelation[Identical]:     baz[#SimpleEnum#]; name=baz
+// TUPLEELEM_1: End completions
+  testTupleElement(arg: (.foo, .bar, .#^TUPLEELEM_2^#))
+// TUPLEELEM_2-NOT: Begin completions
+}