Check that main function is present

4 files changed, 52 insertions, 3 deletions

diff --git a/src/main/java/org/shedlang/compiler/ShedCompiler.java b/src/main/java/org/shedlang/compiler/ShedCompiler.java
index 98583ed1..6e7f187a 100644
--- a/src/main/java/org/shedlang/compiler/ShedCompiler.java
+++ b/src/main/java/org/shedlang/compiler/ShedCompiler.java
@@ -2,6 +2,7 @@ package org.shedlang.compiler;
 
 import org.shedlang.compiler.ast.untyped.UntypedNamespaceNode;
 import org.shedlang.compiler.backends.Backend;
+import org.shedlang.compiler.config.ConfigChecker;
 import org.shedlang.compiler.config.ProjectConfig;
 import org.shedlang.compiler.parser.Parser;
 import org.shedlang.compiler.sources.Sources;
@@ -9,6 +10,7 @@ import org.shedlang.compiler.stackir.StackCompiler;
 import org.shedlang.compiler.stackir.StackIrNamespace;
 import org.shedlang.compiler.typechecker.TypeChecker;
 import org.shedlang.compiler.typechecker.TypeCheckerContext;
+import org.shedlang.compiler.typechecker.TypeInfos;
 import org.shedlang.compiler.types.Effects;
 import org.shedlang.compiler.types.NamespaceName;
 import org.shedlang.compiler.types.Types;
@@ -61,10 +63,14 @@ public class ShedCompiler {
             namespaces.add(stackIrNamespace);
         }
 
+        var typeInfos = typeCheckerContext.toTypeInfos();
+
+        ConfigChecker.configCheck(config, typeInfos);
+
         backend.compile(
             config,
             namespaces,
-            typeCheckerContext.toTypeInfos(),
+            typeInfos,
             config.targetDir().resolve(backend.name())
         );
     }
diff --git a/src/main/java/org/shedlang/compiler/config/ConfigChecker.java b/src/main/java/org/shedlang/compiler/config/ConfigChecker.java
new file mode 100644
index 00000000..83ba3867
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/config/ConfigChecker.java
@@ -0,0 +1,25 @@
+package org.shedlang.compiler.config;
+
+import org.shedlang.compiler.config.errors.ConfigError;
+import org.shedlang.compiler.typechecker.TypeInfos;
+
+public class ConfigChecker {
+    private ConfigChecker() {
+    }
+
+    public static void configCheck(ProjectConfig projectConfig, TypeInfos typeInfos) {
+        for (var binConfig : projectConfig.bins()) {
+            configCheckBin(binConfig, typeInfos);
+        }
+    }
+
+    static void configCheckBin(BinConfig binConfig, TypeInfos typeInfos) {
+        var namespaceTypeInfo = typeInfos.namespaceTypeInfo(binConfig.mainNamespace())
+            // TODO: better error
+            .orElseThrow();
+
+        if (namespaceTypeInfo.fieldType("main").isEmpty()) {
+            throw new ConfigError("Namespace " + binConfig.mainNamespace() + " has no field main");
+        }
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/config/ExampleConfig.java b/src/main/java/org/shedlang/compiler/config/ExampleConfig.java
index 46ca462d..7805feff 100644
--- a/src/main/java/org/shedlang/compiler/config/ExampleConfig.java
+++ b/src/main/java/org/shedlang/compiler/config/ExampleConfig.java
@@ -2,11 +2,18 @@ package org.shedlang.compiler.config;
 
 import org.tomlj.TomlTable;
 
-public record ExampleConfig(String bin, String expectedOutput) {
+import java.util.Optional;
+
+public record ExampleConfig(
+    String bin,
+    Optional<String> expectedOutput,
+    Optional<String> expectedError
+) {
     public static ExampleConfig fromToml(TomlTable table) {
         return new ExampleConfig(
             table.getString("bin"),
-            table.getString("expected-output")
+            Optional.ofNullable(table.getString("expected-output")),
+            Optional.ofNullable(table.getString("expected-error"))
         );
     }
 }
diff --git a/src/main/java/org/shedlang/compiler/config/errors/ConfigError.java b/src/main/java/org/shedlang/compiler/config/errors/ConfigError.java
new file mode 100644
index 00000000..7d847bb3
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/config/errors/ConfigError.java
@@ -0,0 +1,11 @@
+package org.shedlang.compiler.config.errors;
+
+import org.shedlang.compiler.errors.SourceError;
+import org.shedlang.compiler.sources.Sources;
+
+public class ConfigError extends SourceError {
+    public ConfigError(String message) {
+        // TODO: proper source
+        super(message, Sources.NULL);
+    }
+}