Add lint rule for UnusedTaskIntent (#26005)

Adds a new lint rule UnusedTaskIntent. This is similar to UnusedFormal
and UnusedLoopIndex and warns for unused task intents like the following

```chapel
var a = 1;
begin with (ref a) { }
```

Since `a` is not used, it can be safely removed.

Note that the following is not warning for, since task private variables
could have side effects

```chapel
begin with (var x = ...) { }
```

This PR also fixes an issue where `@chplcheck.ignore` was being added to
AstNode's that did not support attributes for the `IncorrectIndentation`
rule

Future work: Improve the naming of sub-location method names like
`block_header` and `header_location`

[Reviewed by @DanilaFe]

test/chplcheck/DoKeywordAndBlock.chpl

@@ -12,15 +12,15 @@ module DoKeywordAndBlock {
   var A: [1..10] int;
 
   @chplcheck.ignore("UnusedLoopIndex")
-  forall i in 1..10 with (ref A) do {}
+  forall i in 1..10 with (ref A) do { A; }
 
   @chplcheck.ignore("UnusedLoopIndex")
   forall i in 1..10 with (ref A) do
-  {}
+  { A; }
 
   @chplcheck.ignore("UnusedLoopIndex")
   forall i in 1..10 with (ref A) do {
-
+    A;
   }
 
   @chplcheck.ignore("UnusedLoopIndex")
@@ -49,8 +49,8 @@ module DoKeywordAndBlock {
     do {}
   for 1..10 do{
   }
-  forall 1..10 with (ref A)do{}
-  forall 1..10 with (ref A)do {}
+  forall 1..10 with (ref A)do{ A; }
+  forall 1..10 with (ref A)do { A; }
 
   on Locales[0] do {}
 

test/chplcheck/DoKeywordAndBlock.good-fixit

@@ -12,15 +12,15 @@ module DoKeywordAndBlock {
   var A: [1..10] int;
 
   @chplcheck.ignore("UnusedLoopIndex")
-  forall i in 1..10 with (ref A) {}
+  forall i in 1..10 with (ref A) { A; }
 
   @chplcheck.ignore("UnusedLoopIndex")
   forall i in 1..10 with (ref A)
-  {}
+  { A; }
 
   @chplcheck.ignore("UnusedLoopIndex")
   forall i in 1..10 with (ref A) {
-
+    A;
   }
 
   @chplcheck.ignore("UnusedLoopIndex")
@@ -49,8 +49,8 @@ module DoKeywordAndBlock {
        {}
   for 1..10 {
   }
-  forall 1..10 with (ref A) {}
-  forall 1..10 with (ref A) {}
+  forall 1..10 with (ref A) { A; }
+  forall 1..10 with (ref A) { A; }
 
   on Locales[0] {}
 

test/chplcheck/IncorrectIndentation.good

@@ -24,10 +24,16 @@ IncorrectIndentation.chpl:137: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:142: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:146: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:151: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:156: node violates rule UnusedTaskIntent
+IncorrectIndentation.chpl:162: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:164: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:167: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:168: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:171: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:173: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:176: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:177: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:180: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:182: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:196: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:197: node violates rule IncorrectIndentation
@@ -36,16 +42,22 @@ IncorrectIndentation.chpl:202: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:207: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:211: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:217: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:220: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:222: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:223: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:226: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:228: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:229: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:232: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:233: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:234: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:237: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:238: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:239: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:242: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:243: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:243: node violates rule IncorrectIndentation
+IncorrectIndentation.chpl:246: node violates rule UnusedTaskIntent
 IncorrectIndentation.chpl:247: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:248: node violates rule IncorrectIndentation
 IncorrectIndentation.chpl:249: node violates rule IncorrectIndentation

test/chplcheck/IncorrectIndentation.good-fixit

@@ -107,13 +107,11 @@ module IncorrectIndentation {
     writeln("??");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
   on here
   {
   writeln("hi");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
   on here {
   writeln("hi");
   }
@@ -139,13 +137,11 @@ module IncorrectIndentation {
     writeln("??");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
   begin
   {
   writeln("hi");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
   begin {
   writeln("hi");
   }
@@ -167,33 +163,31 @@ module IncorrectIndentation {
 
   var dummy: int;
 
-  begin with (ref dummy)
+  begin
   {
     writeln("hi");
     writeln("??");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
-  begin with (ref dummy)
+  begin
   {
   writeln("hi");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
-  begin with (ref dummy) {
+  begin {
   writeln("hi");
   }
 
-  begin with (ref dummy) {
+  begin {
     writeln("hi");
       writeln("hi");
   }
 
-  begin with (ref dummy) {
+  begin {
     writeln("hi"); writeln("hi");
   }
 
-  begin with (ref dummy) {
+  begin {
     @chplcheck.ignore("IncorrectIndentation")
     for 1..10 do
     writeln("hi");
@@ -208,14 +202,12 @@ module IncorrectIndentation {
     writeln("??");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
   cobegin
   {
   writeln("hi");
   writeln("hi");
   }
 
-  @chplcheck.ignore("IncorrectIndentation")
   cobegin {
   writeln("hi");
   writeln("hi");
@@ -237,33 +229,33 @@ module IncorrectIndentation {
     writeln("hi");
   }
 
-  cobegin with (ref dummy)
+  cobegin
   {
     writeln("hi");
     writeln("??");
   }
 
-  cobegin with (ref dummy)
+  cobegin
   {
   writeln("hi");
   writeln("hi");
   }
 
-  cobegin with (ref dummy) {
+  cobegin {
   writeln("hi");
   writeln("hi");
   }
 
-  cobegin with (ref dummy) {
+  cobegin {
     writeln("hi");
       writeln("hi");
   }
 
-  cobegin with (ref dummy) {
+  cobegin {
     writeln("hi"); writeln("hi");
   }
 
-  cobegin with (ref dummy) {
+  cobegin {
     writeln("hi");
     @chplcheck.ignore("IncorrectIndentation")
     for 1..10 do

test/chplcheck/SimpleDomainAsRange.chpl

@@ -61,19 +61,19 @@ module SimpleDomainAsRange {
 
   @chplcheck.ignore("UnusedLoopIndex")
   forall i in {1..#10 by 2 align 2} with (ref A) {
-
+    A;
   }
 
   forall {1..10} with (ref A) {
-
+    A;
   }
 
   forall {1..<10} with (ref A) {
-
+    A;
   }
 
   foreach {1..#10 by 2 align 2} with (ref A) {
-
+    A;
   }
 
   foreach {1..10, 1..10 by 2} {}

test/chplcheck/SimpleDomainAsRange.good-fixit

@@ -61,19 +61,19 @@ module SimpleDomainAsRange {
 
   @chplcheck.ignore("UnusedLoopIndex")
   forall i in 1..#10 by 2 align 2 with (ref A) {
-
+    A;
   }
 
   forall 1..10 with (ref A) {
-
+    A;
   }
 
   forall 1..<10 with (ref A) {
-
+    A;
   }
 
   foreach 1..#10 by 2 align 2 with (ref A) {
-
+    A;
   }
 
   foreach {1..10, 1..10 by 2} {}

test/chplcheck/UnusedTaskIntent.chpl

@@ -0,0 +1,35 @@
+module UnusedTaskIntent {
+  var A: [1..10] int = 10;
+  var B: int = 1;
+
+  forall 1..10 with (var x: int) {}
+
+  forall 1..10 with (var x = B) {}
+
+  foreach 1..10
+    with (ref A,
+          in B) {}
+
+  coforall 1..10 with (+ reduce A) {}
+
+  begin with (ref A,
+  + reduce B) {}
+
+  begin with
+  (ref A) {}
+
+  cobegin with
+  (const in A) { }
+
+  [1..10 with(ref A)] { ; }
+
+  [1..10 with (in A,
+  const in B)] { ; }
+
+  @chplcheck.ignore("UnusedTaskIntent")
+  [1..10 with(ref A)] { ; }
+
+  forall 1..10 with (const A) { }
+  forall 1..10 with (const x: int) { }
+  forall 1..10 with (const x = 1) { }
+}

test/chplcheck/UnusedTaskIntent.good

@@ -0,0 +1,13 @@
+UnusedTaskIntent.chpl:21: warning: cobegin has no effect if it contains fewer than 2 statements
+UnusedTaskIntent.chpl:10: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:11: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:13: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:15: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:16: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:19: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:22: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:24: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:26: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:27: node violates rule UnusedTaskIntent
+UnusedTaskIntent.chpl:32: node violates rule UnusedTaskIntent
+[Success matching fixit for UnusedTaskIntent]

test/chplcheck/UnusedTaskIntent.good-fixit

@@ -0,0 +1,35 @@
+module UnusedTaskIntent {
+  var A: [1..10] int = 10;
+  var B: int = 1;
+
+  forall 1..10 with (var x: int) {}
+
+  forall 1..10 with (var x = B) {}
+
+  @chplcheck.ignore("UnusedTaskIntent")
+  foreach 1..10
+    with (ref A,
+          in B) {}
+
+  coforall 1..10 {}
+
+  begin with (ref A,
+  + reduce B) {}
+
+  begin {}
+
+  cobegin { }
+
+  [1..10] { ; }
+
+  @chplcheck.ignore("UnusedTaskIntent")
+  [1..10 with (in A,
+  const in B)] { ; }
+
+  @chplcheck.ignore("UnusedTaskIntent")
+  [1..10 with(ref A)] { ; }
+
+  forall 1..10 { }
+  forall 1..10 with (const x: int) { }
+  forall 1..10 with (const x = 1) { }
+}

test/chplcheck/activerules.good

@@ -16,4 +16,5 @@ Active rules:
   SimpleDomainAsRange          Warn for simple domains in loops that can be ranges.
   UnusedFormal                 Warn for unused formals in functions.
   UnusedLoopIndex              Warn for unused index variables in loops.
+  UnusedTaskIntent             Warn for unused task intents in functions.
   UnusedTupleUnpack            Warn for unused tuple unpacking, such as '(_, _)'.

test/chplcheck/allrules.good

@@ -19,5 +19,6 @@ Available rules (default rules marked with *):
   * SimpleDomainAsRange          Warn for simple domains in loops that can be ranges.
   * UnusedFormal                 Warn for unused formals in functions.
   * UnusedLoopIndex              Warn for unused index variables in loops.
+  * UnusedTaskIntent             Warn for unused task intents in functions.
   * UnusedTupleUnpack            Warn for unused tuple unpacking, such as '(_, _)'.
     UseExplicitModules           Warn for code that relies on auto-inserted implicit modules.