Remove shadow analyzer from TOOLS_NOGO (#4344)

**What type of PR is this?**

Other

**What does this PR do? Why is it needed?**

The shadow analyzer issues many false positives which are not in keeping
with Go best practices. Even the upstream documentation for this
analyzer admits this and claims that it is experimental. It should not
be included in the default list of analyzers provided by nogo (users can
still opt-in to it if they want it).


**Which issues(s) does this PR fix?**

Fixes #4340

**Other notes for review**

Author: gpanders

go/def.bzl

@@ -103,7 +103,8 @@ _TOOLS_NOGO = [
     "@org_golang_x_tools//go/analysis/passes/nilness:go_default_library",
     "@org_golang_x_tools//go/analysis/passes/pkgfact:go_default_library",
     "@org_golang_x_tools//go/analysis/passes/printf:go_default_library",
-    "@org_golang_x_tools//go/analysis/passes/shadow:go_default_library",
+    # shadow analyzer is too noisy, see #4340
+    # "@org_golang_x_tools//go/analysis/passes/shadow:go_default_library",
     "@org_golang_x_tools//go/analysis/passes/shift:go_default_library",
     "@org_golang_x_tools//go/analysis/passes/sortslice:go_default_library",
     "@org_golang_x_tools//go/analysis/passes/stdmethods:go_default_library",

tests/core/nogo/bzlmod/includes_excludes_test.go

@@ -43,10 +43,10 @@ go_library(
 -- lib.go --
 package lib
 
-func shadowed() string {
+func useless() string {
 	foo := "original"
 	if foo == "original" {
-		foo := "shadow"
+		foo = foo
 		return foo
 	}
 	return foo
@@ -64,10 +64,10 @@ go_library(
 -- go/lib.go --
 package lib
 
-func shadowed() string {
+func useless() string {
 	foo := "original"
 	if foo == "original" {
-		foo := "shadow"
+		foo = foo
 		return foo
 	}
 	return foo
@@ -85,10 +85,10 @@ go_library(
 -- go/third_party/lib.go --
 package lib
 
-func shadowed() string {
+func useless() string {
 	foo := "original"
 	if foo == "original" {
-		foo := "shadow"
+		foo = foo
 		return foo
 	}
 	return foo
@@ -114,8 +114,8 @@ func TestNotIncluded(t *testing.T) {
 func TestIncluded(t *testing.T) {
 	if err := bazel_testing.RunBazel("build", "//go:lib"); err == nil {
 		t.Fatal("Expected build to fail")
-	} else if !strings.Contains(err.Error(), "lib.go:6:3: declaration of \"foo\" shadows declaration at line 4 (shadow)") {
-		t.Fatalf("Expected error to contain \"lib.go:6:3: declaration of \"foo\" shadows declaration at line 4 (shadow)\", got %s", err)
+	} else if !strings.Contains(err.Error(), "lib.go:6:3: self-assignment of foo to foo (assign)") {
+		t.Fatalf("Expected error to contain \"lib.go:6:3: self-assignment of foo to foo (assign)\", got %s", err)
 	}
 }
 

tests/core/nogo/includes_excludes/includes_excludes_test.go

@@ -45,10 +45,10 @@ go_library(
 -- lib.go --
 package lib
 
-func shadowed() string {
+func useless() string {
 	foo := "original"
 	if foo == "original" {
-		foo := "shadow"
+		foo = foo
 		return foo
 	}
 	return foo
@@ -66,10 +66,10 @@ go_library(
 -- go/lib.go --
 package lib
 
-func shadowed() string {
+func useless() string {
 	foo := "original"
 	if foo == "original" {
-		foo := "shadow"
+		foo = foo
 		return foo
 	}
 	return foo
@@ -87,10 +87,10 @@ go_library(
 -- go/third_party/lib.go --
 package lib
 
-func shadowed() string {
+func useless() string {
 	foo := "original"
 	if foo == "original" {
-		foo := "shadow"
+		foo = foo
 		return foo
 	}
 	return foo
@@ -108,8 +108,8 @@ func TestNotIncluded(t *testing.T) {
 func TestIncluded(t *testing.T) {
 	if err := bazel_testing.RunBazel("build", "//go:lib"); err == nil {
 		t.Fatal("Expected build to fail")
-	} else if !strings.Contains(err.Error(), "lib.go:6:3: declaration of \"foo\" shadows declaration at line 4 (shadow)") {
-		t.Fatalf("Expected error to contain \"lib.go:6:3: declaration of \"foo\" shadows declaration at line 4 (shadow)\", got %s", err)
+	} else if !strings.Contains(err.Error(), "lib.go:6:3: self-assignment of foo to foo (assign)") {
+		t.Fatalf("Expected error to contain \"lib.go:6:3: self-assignment of foo to foo (assign)\", got %s", err)
 	}
 }