Analyzer: Static warnings are reported as errors

[eernstg]

Static warnings exist in Dart again, cf. issue #34349, and they should be reported as such and recognized in tests via the outcome expectation static type warning. However, using a fresh SDK checkout (commit fa0d991), the following program gives rise to test failures as shown below:

class A {
  int //# 0: static type warning
  operator []=(x, y) {}
  void f([int i = 0]) {}
}

int //# 1: static type warning
set setter(value) {}

int get foo => 42;
set foo(
  String //# 2: static type warning
  s) {}

class B extends A {
  void f([int i = 1]) {} //# 3: static type warning
}

enum E { one, two, three }

void useE() {
  var v = E.one;
  switch (v) {
    case E.one: break;
    case E.two: break;
    /* //# 4: static type warning
    case E.three: break;
    */ //# 4: continued
  }
}

int bar() { return; } //# 5: static type warning

Future<int> barAsync() async { return; } //# 6: static type warning

main() {
  A()[0] = 0;
  setter = null;
  foo;
  foo = null;
  B().f();
  useE();
  bar(); //# 5: continued
  barAsync(); //# 6: continued
}

Here is the output:

tools/testing/dart/main.dart:1: Warning: Interpreting this as package URI, 'package:test_dart/main.dart'.
Test configuration:
    custom configuration(architecture: x64, compiler: dart2analyzer, mode: release, runtime: none, system: linux, vm-options: [], timeout: 960, host-checked, preview-dart-2)
Suites tested: language_2

FAILED: dart2analyzer-none release_x64 language_2/scratch_test/2
Expected: Pass
Actual: CompileTimeError

--- Command "dart2analyzer" (took 10.000758s):
DART_CONFIGURATION=ReleaseX64 sdk/bin/dartanalyzer_developer --ignore-unrecognized-flags --packages=/usr/local/google/home/eernst/devel/dart/work/sdk/.packages --format=machine --no-hints /usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_2.dart

exit code:
1

stderr:
ERROR|STATIC_WARNING|MISMATCHED_GETTER_AND_SETTER_TYPES|/usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_2.dart|12|1|18|The return type of getter 'foo' is 'int' which isn't assignable to the type 'String' of its setter 'foo'.

--- Re-run this test:
python tools/test.py -m release -c dart2analyzer -r none --host-checked -t 960 language_2/scratch_test/2

[00:11 |  12% | +    0 | -    1]
FAILED: dart2analyzer-none release_x64 language_2/scratch_test/5
Expected: Pass
Actual: CompileTimeError

--- Command "dart2analyzer" (took 10.000751s):
DART_CONFIGURATION=ReleaseX64 sdk/bin/dartanalyzer_developer --ignore-unrecognized-flags --packages=/usr/local/google/home/eernst/devel/dart/work/sdk/.packages --format=machine --no-hints /usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_5.dart

exit code:
1

stderr:
ERROR|STATIC_WARNING|RETURN_WITHOUT_VALUE|/usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_5.dart|34|13|7|Missing return value after 'return'.

--- Re-run this test:
python tools/test.py -m release -c dart2analyzer -r none --host-checked -t 960 language_2/scratch_test/5

[00:11 |  50% | +    2 | -    2]
FAILED: dart2analyzer-none release_x64 language_2/scratch_test/0
Expected: Pass
Actual: CompileTimeError

--- Command "dart2analyzer" (took 11.000286s):
DART_CONFIGURATION=ReleaseX64 sdk/bin/dartanalyzer_developer --ignore-unrecognized-flags --packages=/usr/local/google/home/eernst/devel/dart/work/sdk/.packages --format=machine --no-hints /usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_0.dart

exit code:
1

stderr:
ERROR|STATIC_WARNING|NON_VOID_RETURN_FOR_OPERATOR|/usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_0.dart|4|3|3|The return type of the operator []= must be 'void'.

--- Re-run this test:
python tools/test.py -m release -c dart2analyzer -r none --host-checked -t 960 language_2/scratch_test/0

[00:11 |  62% | +    2 | -    3]
FAILED: dart2analyzer-none release_x64 language_2/scratch_test/6
Expected: Pass
Actual: CompileTimeError

--- Command "dart2analyzer" (took 11.000320s):
DART_CONFIGURATION=ReleaseX64 sdk/bin/dartanalyzer_developer --ignore-unrecognized-flags --packages=/usr/local/google/home/eernst/devel/dart/work/sdk/.packages --format=machine --no-hints /usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_6.dart

exit code:
1

stderr:
ERROR|STATIC_WARNING|RETURN_WITHOUT_VALUE|/usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_6.dart|36|32|7|Missing return value after 'return'.

--- Re-run this test:
python tools/test.py -m release -c dart2analyzer -r none --host-checked -t 960 language_2/scratch_test/6

[00:11 |  75% | +    2 | -    4]
FAILED: dart2analyzer-none release_x64 language_2/scratch_test/1
Expected: Pass
Actual: CompileTimeError

--- Command "dart2analyzer" (took 11.000416s):
DART_CONFIGURATION=ReleaseX64 sdk/bin/dartanalyzer_developer --ignore-unrecognized-flags --packages=/usr/local/google/home/eernst/devel/dart/work/sdk/.packages --format=machine --no-hints /usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_1.dart

exit code:
1

stderr:
ERROR|STATIC_WARNING|NON_VOID_RETURN_FOR_SETTER|/usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_1.dart|9|1|3|The return type of the setter must be 'void' or absent.

--- Re-run this test:
python tools/test.py -m release -c dart2analyzer -r none --host-checked -t 960 language_2/scratch_test/1

[00:11 |  87% | +    2 | -    5]
FAILED: dart2analyzer-none release_x64 language_2/scratch_test/4
Expected: Pass
Actual: CompileTimeError

--- Command "dart2analyzer" (took 11.000395s):
DART_CONFIGURATION=ReleaseX64 sdk/bin/dartanalyzer_developer --ignore-unrecognized-flags --packages=/usr/local/google/home/eernst/devel/dart/work/sdk/.packages --format=machine --no-hints /usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_4.dart

exit code:
1

stderr:
ERROR|STATIC_WARNING|MISSING_ENUM_CONSTANT_IN_SWITCH|/usr/local/google/home/eernst/devel/dart/work/sdk/out/ReleaseX64/generated_tests/language_2/scratch_test_4.dart|25|3|10|Missing case clause for 'three'.

--- Re-run this test:
python tools/test.py -m release -c dart2analyzer -r none --host-checked -t 960 language_2/scratch_test/4

[00:11 | 100% | +    2 | -    6]

The subtest 3 (about default values) succeeds, reporting 'WARNING|STATIC_WARNING'.

All other subtests fail because the outcome is 'ERROR|STATIC_WARNING', which is not recognized by 'test.dart' as a static type warning. It is not obvious to me whether it's analyzer or 'test.dart' that needs to be adjusted in order to make these subtests succeed.

Note that it's being debated whether the invalid return; statements should be an error or a warning (dart-lang/language#255), which is significant for subtest 5 and 6.

[eernstg]

Current status: This topic needs to be clarified, so we'll make it 'area-language' until a decision has been made on the use of warnings in Dart in general.

[eernstg]

Closing, the language change decision is handled via dart-lang/language#1012.