Report the most expensive statements as diagnostics

Author: amcasey

src/compiler/checker.ts

@@ -328,12 +328,6 @@ namespace ts {
         const keyofStringsOnly = !!compilerOptions.keyofStringsOnly;
         const freshObjectLiteralFlag = compilerOptions.suppressExcessPropertyErrors ? 0 : ObjectFlags.FreshLiteral;
 
-        interface ExpensiveStatement {
-            node: Node;
-            typeDelta: number;
-            symbolDelta: number;
-        }
-
         let ignoreExpensiveStatement = true;
         const maxExpensiveStatementCount = compilerOptions.expensiveStatements ?? 0;
         const expensiveStatements: ExpensiveStatement[] = [];
@@ -373,6 +367,7 @@ namespace ts {
                 subtype: subtypeRelation.size,
                 strictSubtype: strictSubtypeRelation.size,
             }),
+            getExpensiveStatements: () => expensiveStatements,
             isUndefinedSymbol: symbol => symbol === undefinedSymbol,
             isArgumentsSymbol: symbol => symbol === argumentsSymbol,
             isUnknownSymbol: symbol => symbol === unknownSymbol,

src/compiler/program.ts

@@ -950,6 +950,7 @@ namespace ts {
             getTypeCount: () => getDiagnosticsProducingTypeChecker().getTypeCount(),
             getInstantiationCount: () => getDiagnosticsProducingTypeChecker().getInstantiationCount(),
             getRelationCacheSizes: () => getDiagnosticsProducingTypeChecker().getRelationCacheSizes(),
+            getExpensiveStatements: () => getDiagnosticsProducingTypeChecker().getExpensiveStatements(),
             getFileProcessingDiagnostics: () => fileProcessingDiagnostics,
             getResolvedTypeReferenceDirectives: () => resolvedTypeReferenceDirectives,
             isSourceFileFromExternalLibrary,

src/compiler/types.ts

@@ -3261,6 +3261,7 @@ namespace ts {
         getTypeCount(): number;
         getInstantiationCount(): number;
         getRelationCacheSizes(): { assignable: number, identity: number, subtype: number, strictSubtype: number };
+        getExpensiveStatements(): readonly ExpensiveStatement[];
 
         /* @internal */ getFileProcessingDiagnostics(): DiagnosticCollection;
         /* @internal */ getResolvedTypeReferenceDirectives(): Map<ResolvedTypeReferenceDirective | undefined>;
@@ -3592,6 +3593,7 @@ namespace ts {
         /* @internal */ getTypeCount(): number;
         /* @internal */ getInstantiationCount(): number;
         /* @internal */ getRelationCacheSizes(): { assignable: number, identity: number, subtype: number, strictSubtype: number };
+        /* @internal */ getExpensiveStatements(): readonly ExpensiveStatement[];
 
         /* @internal */ isArrayType(type: Type): boolean;
         /* @internal */ isTupleType(type: Type): boolean;
@@ -6737,4 +6739,11 @@ namespace ts {
         negative: boolean;
         base10Value: string;
     }
+
+    /* @internal */
+    export interface ExpensiveStatement {
+        node: Node;
+        typeDelta: number;
+        symbolDelta: number;
+    }
 }

src/executeCommandLine/executeCommandLine.ts

@@ -440,7 +440,7 @@ namespace ts {
                 createBuilderStatusReporter(sys, shouldBePretty(sys, buildOptions)),
                 createWatchStatusReporter(sys, buildOptions)
             );
-            updateSolutionBuilderHost(sys, cb, buildHost);
+            updateSolutionBuilderHost(sys, reportDiagnostic, cb, buildHost);
             const builder = createSolutionBuilderWithWatch(buildHost, projects, buildOptions, watchOptions);
             builder.build();
             return builder;
@@ -453,7 +453,7 @@ namespace ts {
             createBuilderStatusReporter(sys, shouldBePretty(sys, buildOptions)),
             createReportErrorSummary(sys, buildOptions)
         );
-        updateSolutionBuilderHost(sys, cb, buildHost);
+        updateSolutionBuilderHost(sys, reportDiagnostic, cb, buildHost);
         const builder = createSolutionBuilder(buildHost, projects, buildOptions);
         const exitStatus = buildOptions.clean ? builder.clean() : builder.build();
         return sys.exit(exitStatus);
@@ -492,7 +492,7 @@ namespace ts {
             s => sys.write(s + sys.newLine),
             createReportErrorSummary(sys, options)
         );
-        reportStatistics(sys, program);
+        reportStatistics(sys, program, reportDiagnostic);
         cb(program);
         return sys.exit(exitStatus);
     }
@@ -516,7 +516,7 @@ namespace ts {
             reportDiagnostic,
             reportErrorSummary: createReportErrorSummary(sys, options),
             afterProgramEmitAndDiagnostics: builderProgram => {
-                reportStatistics(sys, builderProgram.getProgram());
+                reportStatistics(sys, builderProgram.getProgram(), reportDiagnostic);
                 cb(builderProgram);
             }
         });
@@ -525,12 +525,13 @@ namespace ts {
 
     function updateSolutionBuilderHost(
         sys: System,
+        reportDiagnostic: DiagnosticReporter,
         cb: ExecuteCommandLineCallbacks,
         buildHost: SolutionBuilderHostBase<EmitAndSemanticDiagnosticsBuilderProgram>
     ) {
         updateCreateProgram(sys, buildHost);
         buildHost.afterProgramEmitAndDiagnostics = program => {
-            reportStatistics(sys, program.getProgram());
+            reportStatistics(sys, program.getProgram(), reportDiagnostic);
             cb(program);
         };
         buildHost.afterEmitBundle = cb;
@@ -549,14 +550,15 @@ namespace ts {
 
     function updateWatchCompilationHost(
         sys: System,
+        reportDiagnostic: DiagnosticReporter,
         cb: ExecuteCommandLineCallbacks,
         watchCompilerHost: WatchCompilerHost<EmitAndSemanticDiagnosticsBuilderProgram>,
     ) {
         updateCreateProgram(sys, watchCompilerHost);
         const emitFilesUsingBuilder = watchCompilerHost.afterProgramCreate!; // TODO: GH#18217
         watchCompilerHost.afterProgramCreate = builderProgram => {
             emitFilesUsingBuilder(builderProgram);
-            reportStatistics(sys, builderProgram.getProgram());
+            reportStatistics(sys, builderProgram.getProgram(), reportDiagnostic);
             cb(builderProgram);
         };
     }
@@ -581,7 +583,7 @@ namespace ts {
             reportDiagnostic,
             reportWatchStatus: createWatchStatusReporter(system, configParseResult.options)
         });
-        updateWatchCompilationHost(system, cb, watchCompilerHost);
+        updateWatchCompilationHost(system, reportDiagnostic, cb, watchCompilerHost);
         watchCompilerHost.configFileParsingResult = configParseResult;
         return createWatchProgram(watchCompilerHost);
     }
@@ -602,7 +604,7 @@ namespace ts {
             reportDiagnostic,
             reportWatchStatus: createWatchStatusReporter(system, options)
         });
-        updateWatchCompilationHost(system, cb, watchCompilerHost);
+        updateWatchCompilationHost(system, reportDiagnostic, cb, watchCompilerHost);
         return createWatchProgram(watchCompilerHost);
     }
 
@@ -616,9 +618,21 @@ namespace ts {
         }
     }
 
-    function reportStatistics(sys: System, program: Program) {
+    function reportStatistics(sys: System, program: Program, reportDiagnostic: DiagnosticReporter) {
         let statistics: Statistic[];
         const compilerOptions = program.getCompilerOptions();
+
+        if (compilerOptions.expensiveStatements) {
+            for (const expensiveStatement of program.getExpensiveStatements()) {
+                reportDiagnostic(
+                    createDiagnosticForNode(
+                        expensiveStatement.node,
+                        Diagnostics.Checking_this_statement_may_result_in_the_creation_of_as_many_as_0_types_and_1_symbols,
+                        expensiveStatement.typeDelta,
+                        expensiveStatement.symbolDelta));
+            }
+        }
+
         if (canReportDiagnostics(sys, compilerOptions)) {
             statistics = [];
             const memoryUsed = sys.getMemoryUsage ? sys.getMemoryUsage() : -1;