Adding diagnostic error on binary operations with incompatible types (microsoft#1254)

* Adding diagnostic error for binary operations with incompatible types - e.g 5 + 'str'

Author: CTrando

src/Analysis/Ast/Impl/Analyzer/Evaluation/ExpressionEval.Operators.cs

@@ -13,13 +13,15 @@
 // See the Apache Version 2.0 License for specific language governing
 // permissions and limitations under the License.
 
-using System.Collections.Generic;
+using Microsoft.Python.Analysis.Diagnostics;
 using Microsoft.Python.Analysis.Modules;
 using Microsoft.Python.Analysis.Types;
 using Microsoft.Python.Analysis.Types.Collections;
 using Microsoft.Python.Analysis.Values;
+using Microsoft.Python.Core;
 using Microsoft.Python.Parsing;
 using Microsoft.Python.Parsing.Ast;
+using ErrorCodes = Microsoft.Python.Analysis.Diagnostics.ErrorCodes;
 
 namespace Microsoft.Python.Analysis.Analyzer.Evaluation {
     internal sealed partial class ExpressionEval {
@@ -122,6 +124,9 @@ private IMember GetValueFromBinaryOp(Expression expr) {
 
             if (leftIsSupported && rightIsSupported) {
                 if (TryGetValueFromBuiltinBinaryOp(op, leftTypeId, rightTypeId, Interpreter.LanguageVersion.Is3x(), out var member)) {
+                    if (member.IsUnknown()) {
+                        ReportOperatorDiagnostics(expr, leftType, rightType, op);
+                    }
                     return member;
                 }
             }
@@ -435,5 +440,14 @@ private static (string name, string swappedName) OpMethodName(PythonOperator op)
 
             return (null, null);
         }
+        private void ReportOperatorDiagnostics(Expression expr, IPythonType leftType, IPythonType rightType, PythonOperator op) {
+            ReportDiagnostics(Module.Uri, new DiagnosticsEntry(
+                Resources.UnsupporedOperandType.FormatInvariant(op.ToCodeString(), leftType.Name, rightType.Name),
+                GetLocation(expr).Span,
+                ErrorCodes.UnsupportedOperandType,
+                Severity.Error,
+                DiagnosticSource.Analysis));
+        }
+
     }
 }

src/Analysis/Ast/Impl/Diagnostics/ErrorCodes.cs

@@ -25,6 +25,7 @@ public static class ErrorCodes {
         public const string UndefinedVariable = "undefined-variable";
         public const string VariableNotDefinedGlobally= "variable-not-defined-globally";
         public const string VariableNotDefinedNonLocal = "variable-not-defined-nonlocal";
+        public const string UnsupportedOperandType = "unsupported-operand-type";
         public const string ReturnInInit = "return-in-init";
         public const string TypingGenericArguments = "typing-generic-arguments";
     }

src/Analysis/Ast/Impl/Resources.Designer.cs

@@ -189,6 +189,9 @@
   <data name="UnableToDetermineCachePathException" xml:space="preserve">
     <value>Unable to determine analysis cache path. Exception: {0}. Using default '{1}'.</value>
   </data>
+  <data name="UnsupporedOperandType" xml:space="preserve">
+    <value>Unsupported operand types for '{0}': '{1}' and '{2}'</value>
+  </data>
   <data name="ReturnInInit" xml:space="preserve">
     <value>Explicit return in __init__ </value>
   </data>
@@ -198,4 +201,4 @@
   <data name="GenericNotAllUnique" xml:space="preserve">
     <value>Arguments to Generic must all be unique.</value>
   </data>
-</root>
+</root>

src/Analysis/Ast/Impl/Resources.resx

@@ -0,0 +1,86 @@
+using System.Linq;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.Python.Analysis.Tests.FluentAssertions;
+using Microsoft.Python.Core;
+using Microsoft.Python.Parsing.Tests;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using TestUtilities;
+
+namespace Microsoft.Python.Analysis.Tests {
+    [TestClass]
+    public class LintOperatorTests : AnalysisTestBase {
+
+        public TestContext TestContext { get; set; }
+
+        [TestInitialize]
+        public void TestInitialize()
+            => TestEnvironmentImpl.TestInitialize($"{TestContext.FullyQualifiedTestClassName}.{TestContext.TestName}");
+
+        [TestCleanup]
+        public void Cleanup() => TestEnvironmentImpl.TestCleanup();
+
+        [TestMethod, Priority(0)]
+        public async Task IncompatibleTypesBinaryOpBasic() {
+            var code = $@"
+a = 5 + 'str'
+";
+
+            var analysis = await GetAnalysisAsync(code, PythonVersions.LatestAvailable3X);
+            analysis.Diagnostics.Should().HaveCount(1);
+
+            var diagnostic = analysis.Diagnostics.ElementAt(0);
+            diagnostic.SourceSpan.Should().Be(2, 5, 2, 14);
+            diagnostic.ErrorCode.Should().Be(Diagnostics.ErrorCodes.UnsupportedOperandType);
+            diagnostic.Message.Should().Be(Resources.UnsupporedOperandType.FormatInvariant("+", "int", "str"));
+        }
+
+        [DataRow("str", "int", "+")]
+        [DataRow("str", "int", "-")]
+        [DataRow("str", "int", "/")]
+        [DataRow("str", "float", "+")]
+        [DataRow("str", "float", "-")]
+        [DataRow("str", "float", "*")]
+        [DataTestMethod, Priority(0)]
+        public async Task IncompatibleTypesBinaryOp(string leftType, string rightType, string op) {
+ var code = $@"
+x = 1
+y = 2
+
+z = {leftType}(x) {op} {rightType}(y)
+";
+
+            var analysis = await GetAnalysisAsync(code, PythonVersions.LatestAvailable3X);
+            analysis.Diagnostics.Should().HaveCount(1);
+
+            var diagnostic = analysis.Diagnostics.ElementAt(0);
+
+
+            string line = $"z = {leftType}(x) {op} {rightType}(y)";
+            // source span is 1 indexed
+            diagnostic.SourceSpan.Should().Be(5, line.IndexOf(leftType) + 1, 5, line.IndexOf("(y)") + 4);
+            diagnostic.ErrorCode.Should().Be(Diagnostics.ErrorCodes.UnsupportedOperandType);
+            diagnostic.Message.Should().Be(Resources.UnsupporedOperandType.FormatInvariant(op, leftType, rightType));
+        }
+
+        [DataRow("str", "str", "+")]
+        [DataRow("int", "int", "-")]
+        [DataRow("bool", "int", "/")]
+        [DataRow("float", "int", "+")]
+        [DataRow("complex", "float", "-")]
+        [DataRow("str", "int", "*")]
+        [DataTestMethod, Priority(0)]
+        public async Task CompatibleTypesBinaryOp(string leftType, string rightType, string op) {
+            var code = $@"
+x = 1
+y = 2
+
+z = {leftType}(x) {op} {rightType}(y)
+";
+
+            var analysis = await GetAnalysisAsync(code, PythonVersions.LatestAvailable3X);
+            analysis.Diagnostics.Should().BeEmpty();
+        }
+    }
+
+}