From 8d8fea8a57068a0c5f0c1df766679a25f4272481 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Sat, 28 Nov 2020 18:22:45 -0800
Subject: [PATCH] compiler: always use int context for index values

For golang/go#14844

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/273889
---
 gcc/go/gofrontend/MERGE              |  2 +-
 gcc/go/gofrontend/expressions.cc     | 31 +++++-----------------------
 gcc/testsuite/go.test/test/shift1.go | 18 ++++++++++------
 3 files changed, 18 insertions(+), 33 deletions(-)

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index af4d0526b2f..698969fc8c8 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-68b1c7659a6b25d537a4ff3365ab070fa6215b0b
+af683486b4de5503b2b6d9ae974a2ab1eeb92290
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc
index dc7399ebb3a..d1546300d0e 100644
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -12802,24 +12802,11 @@ Array_index_expression::do_determine_type(const Type_context*)
   this->array_->determine_type_no_context();
 
   Type_context index_context(Type::lookup_integer_type("int"), false);
-  if (this->start_->is_constant())
-    this->start_->determine_type(&index_context);
-  else
-    this->start_->determine_type_no_context();
+  this->start_->determine_type(&index_context);
   if (this->end_ != NULL)
-    {
-      if (this->end_->is_constant())
-        this->end_->determine_type(&index_context);
-      else
-        this->end_->determine_type_no_context();
-    }
+    this->end_->determine_type(&index_context);
   if (this->cap_ != NULL)
-    {
-      if (this->cap_->is_constant())
-        this->cap_->determine_type(&index_context);
-      else
-        this->cap_->determine_type_no_context();
-    }
+    this->cap_->determine_type(&index_context);
 }
 
 // Check types of an array index.
@@ -13488,17 +13475,9 @@ String_index_expression::do_determine_type(const Type_context*)
   this->string_->determine_type_no_context();
 
   Type_context index_context(Type::lookup_integer_type("int"), false);
-  if (this->start_->is_constant())
-    this->start_->determine_type(&index_context);
-  else
-    this->start_->determine_type_no_context();
+  this->start_->determine_type(&index_context);
   if (this->end_ != NULL)
-    {
-      if (this->end_->is_constant())
-        this->end_->determine_type(&index_context);
-      else
-        this->end_->determine_type_no_context();
-    }
+    this->end_->determine_type(&index_context);
 }
 
 // Check types of a string index.
diff --git a/gcc/testsuite/go.test/test/shift1.go b/gcc/testsuite/go.test/test/shift1.go
index 04f5321b73f..d6a6c38839f 100644
--- a/gcc/testsuite/go.test/test/shift1.go
+++ b/gcc/testsuite/go.test/test/shift1.go
@@ -1,6 +1,6 @@
 // errorcheck
 
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -18,13 +18,13 @@ func h(x float64) int     { return 0 }
 var (
 	s uint    = 33
 	u         = 1.0 << s // ERROR "invalid operation|shift of non-integer operand"
-	v float32 = 1 << s   // ERROR "invalid" "as type float32"
+	v float32 = 1 << s   // ERROR "invalid"
 )
 
 // non-constant shift expressions
 var (
-	e1       = g(2.0 << s) // ERROR "invalid|shift of non-integer operand" "as type interface"
-	f1       = h(2 << s)   // ERROR "invalid" "as type float64"
+	e1       = g(2.0 << s) // ERROR "invalid|shift of non-integer operand"
+	f1       = h(2 << s)   // ERROR "invalid"
 	g1 int64 = 1.1 << s    // ERROR "truncated"
 )
 
@@ -66,8 +66,15 @@ func _() {
 		u2         = 1<<s != 1.0 // ERROR "non-integer|float64"
 		v  float32 = 1 << s      // ERROR "non-integer|float32"
 		w  int64   = 1.0 << 33   // 1.0<<33 is a constant shift expression
+
 		_, _, _, _, _, _, _, _, _, _ = j, k, m, n, o, u, u1, u2, v, w
 	)
+
+	// non constants arguments trigger a different path
+	f2 := 1.2
+	s2 := "hi"
+	_ = f2 << 2 // ERROR "shift of type float64|non-integer"
+	_ = s2 << 2 // ERROR "shift of type string|non-integer"
 }
 
 // shifts in comparisons w/ untyped operands
@@ -146,8 +153,7 @@ func _() {
 	var a []int
 	_ = a[1<<s]
 	_ = a[1.]
-	// For now, the spec disallows these. We may revisit past Go 1.1.
-	_ = a[1.<<s]  // ERROR "integer|shift of type float64"
+	_ = a[1.<<s]
 	_ = a[1.1<<s] // ERROR "integer|shift of type float64"
 
 	_ = make([]int, 1)
-- 
2.30.2