Add Kotlin/JVM support (#2637)

* Add Kotlin/JVM support

* Update CONTRIBUTORS.md

* Use kotlinc-jvm instead of kotlinc

* Fix alphabetical ordering

* Filter kotlin compiler arguments

Extract user options filtering for java into a separate function to
handle filtering options with extra arguments.
Filter kotlin compiler options: -d, -jdk-home, -kotlin-home, -script, -progressive

* Filter -Xjavac user options

Filter any option that starts with '-Xjavac', as it could be used to pass unwanted options through kotlinc to javac.

* Fix year in copyright

Co-authored-by: Rubén Rincón Blanco <ruben@rinconblanco.es>

* Add kotlin.amazon.properties

* Add JAVA_HOME to kotlin default exec options

Query per-compiler property 'java_home' and set environment

* Add java_home to kotlin properties

Co-authored-by: Daniel Below <daniel.below@jetbrains.com>
Co-authored-by: Rubén Rincón Blanco <ruben@rinconblanco.es>

13 files changed, 196 insertions, 14 deletions

diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index 0f3166699..d1ff773e4 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -100,3 +100,4 @@ From oldest to newest contributor, we would like to thank:
 - [Dan Okken](https://github.com/okkenator)
 - [Shivam Gupta](https://github.com/xgupta)
 - [Tamir Bahar](https://github.com/tmr232)
+- [Daniel Below](https://github.com/DanielBelow)
diff --git a/etc/config/kotlin.amazon.properties b/etc/config/kotlin.amazon.properties
new file mode 100644
index 000000000..5f7776fa7
--- /dev/null
+++ b/etc/config/kotlin.amazon.properties
@@ -0,0 +1,38 @@
+compilers=&kotlin
+compilerType=kotlin
+versionFlag=-version
+objdumper=javap
+instructionSet=java
+defaultCompiler=kotlinc1500
+demangler=
+postProcess=
+options=
+supportsBinary=false
+needsMulti=false
+supportsExecute=false
+
+group.kotlin.compilers=kotlinc1400:kotlinc1410:kotlinc1420:kotlinc1421:kotlinc1430:kotlinc1431:kotlinc1432:kotlinc1500
+compiler.kotlinc1400.exe=/opt/compiler-explorer/kotlin-jvm-1.4.0/bin/kotlinc-jvm
+compiler.kotlinc1400.name=kotlinc 1.4.0
+compiler.kotlinc1400.java_home=/opt/compiler-explorer/jdk-16.0.1
+compiler.kotlinc1410.exe=/opt/compiler-explorer/kotlin-jvm-1.4.10/bin/kotlinc-jvm
+compiler.kotlinc1410.name=kotlinc 1.4.10
+compiler.kotlinc1410.java_home=/opt/compiler-explorer/jdk-16.0.1
+compiler.kotlinc1420.exe=/opt/compiler-explorer/kotlin-jvm-1.4.20/bin/kotlinc-jvm
+compiler.kotlinc1420.name=kotlinc 1.4.20
+compiler.kotlinc1420.java_home=/opt/compiler-explorer/jdk-16.0.1
+compiler.kotlinc1421.exe=/opt/compiler-explorer/kotlin-jvm-1.4.21/bin/kotlinc-jvm
+compiler.kotlinc1421.name=kotlinc 1.4.21
+compiler.kotlinc1421.java_home=/opt/compiler-explorer/jdk-16.0.1
+compiler.kotlinc1430.exe=/opt/compiler-explorer/kotlin-jvm-1.4.30/bin/kotlinc-jvm
+compiler.kotlinc1430.name=kotlinc 1.4.30
+compiler.kotlinc1430.java_home=/opt/compiler-explorer/jdk-16.0.1
+compiler.kotlinc1431.exe=/opt/compiler-explorer/kotlin-jvm-1.4.31/bin/kotlinc-jvm
+compiler.kotlinc1431.name=kotlinc 1.4.31
+compiler.kotlinc1431.java_home=/opt/compiler-explorer/jdk-16.0.1
+compiler.kotlinc1432.exe=/opt/compiler-explorer/kotlin-jvm-1.4.32/bin/kotlinc-jvm
+compiler.kotlinc1432.name=kotlinc 1.4.32
+compiler.kotlinc1432.java_home=/opt/compiler-explorer/jdk-16.0.1
+compiler.kotlinc1500.exe=/opt/compiler-explorer/kotlin-jvm-1.5.0/bin/kotlinc-jvm
+compiler.kotlinc1500.name=kotlinc 1.5.0
+compiler.kotlinc1500.java_home=/opt/compiler-explorer/jdk-16.0.1
diff --git a/etc/config/kotlin.defaults.properties b/etc/config/kotlin.defaults.properties
new file mode 100644
index 000000000..374dc6965
--- /dev/null
+++ b/etc/config/kotlin.defaults.properties
@@ -0,0 +1,18 @@
+# Default settings for Kotlin/JVM
+compilers=&kotlin
+compilerType=kotlin
+versionFlag=-version
+objdumper=javap
+instructionSet=java
+
+group.kotlin.compilers=kotlincdefault
+compiler.kotlincdefault.exe=/usr/bin/kotlinc-jvm
+compiler.kotlincdefault.name=kotlinc default
+
+defaultCompiler=kotlincdefault
+demangler=
+postProcess=
+options=
+supportsBinary=false
+needsMulti=false
+supportsExecute=false
diff --git a/examples/kotlin/default.kt b/examples/kotlin/default.kt
new file mode 100644
index 000000000..b1576c436
--- /dev/null
+++ b/examples/kotlin/default.kt
@@ -0,0 +1,2 @@
+// Type your code here, or load an example.
+fun square(num: Int): Int = num * num
diff --git a/lib/compilers/_all.js b/lib/compilers/_all.js
index f6e9e65af..5af9f3c70 100644
--- a/lib/compilers/_all.js
+++ b/lib/compilers/_all.js
@@ -42,6 +42,7 @@ export { GolangCompiler } from './golang';
 export { HaskellCompiler } from './haskell';
 export { ISPCCompiler } from './ispc';
 export { JavaCompiler } from './java';
+export { KotlinCompiler } from './kotlin';
 export { LDCCompiler } from './ldc';
 export { LLCCompiler } from './llc';
 export { LLVMmcaTool } from './llvm-mca';
diff --git a/lib/compilers/argument-parsers.js b/lib/compilers/argument-parsers.js
index 6b139c829..750e9c2ef 100644
--- a/lib/compilers/argument-parsers.js
+++ b/lib/compilers/argument-parsers.js
@@ -178,6 +178,13 @@ export class JavaParser extends BaseParser {
     }
 }
 
+export class KotlinParser extends BaseParser {
+    static async parse(compiler) {
+        await KotlinParser.getOptions(compiler, '-help');
+        return compiler;
+    }
+}
+
 export class VCParser extends BaseParser {
     static async parse(compiler) {
         await VCParser.getOptions(compiler, '/help');
diff --git a/lib/compilers/java.js b/lib/compilers/java.js
index 677eeb323..c61cc8f65 100644
--- a/lib/compilers/java.js
+++ b/lib/compilers/java.js
@@ -111,22 +111,10 @@ export class JavaCompiler extends BaseCompiler {
         return path.join(dirPath, `${path.basename(this.compileFilename, this.lang.extensions[0])}.class`);
     }
 
-    filterUserOptions(userOptions) {
+    filterUserOptionsWithArg(userOptions, oneArgForbiddenList) {
         const filteredOptions = [];
         let toSkip = 0;
 
-        const oneArgForbiddenList = new Set([
-            // -d directory
-            // Sets the destination directory for class files.
-            '-d',
-            // -s directory
-            // Specifies the directory used to place the generated source files.
-            '-s',
-            // --source-path path or -sourcepath path
-            // Specifies where to find input source files.
-            '--source-path', '-sourcepath',
-        ]);
-
         for (const userOption of userOptions) {
             if (toSkip > 0) {
                 toSkip--;
@@ -143,6 +131,22 @@ export class JavaCompiler extends BaseCompiler {
         return filteredOptions;
     }
 
+    filterUserOptions(userOptions) {
+        const oneArgForbiddenList = new Set([
+            // -d directory
+            // Sets the destination directory for class files.
+            '-d',
+            // -s directory
+            // Specifies the directory used to place the generated source files.
+            '-s',
+            // --source-path path or -sourcepath path
+            // Specifies where to find input source files.
+            '--source-path', '-sourcepath',
+        ]);
+
+        return this.filterUserOptionsWithArg(userOptions, oneArgForbiddenList);
+    }
+
     processAsm(result) {
         // Handle "error" documents.
         if (!result.asm.includes('\n') && result.asm[0] === '<') {
diff --git a/lib/compilers/kotlin.js b/lib/compilers/kotlin.js
new file mode 100644
index 000000000..a7e21f796
--- /dev/null
+++ b/lib/compilers/kotlin.js
@@ -0,0 +1,78 @@
+// Copyright (c) 2021, Compiler Explorer Authors
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//     * Redistributions of source code must retain the above copyright notice,
+//       this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above copyright
+//       notice, this list of conditions and the following disclaimer in the
+//       documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+
+import { KotlinParser } from './argument-parsers';
+import { JavaCompiler } from './java';
+
+export class KotlinCompiler extends JavaCompiler {
+    static get key() {
+        return 'kotlin';
+    }
+
+    getDefaultExecOptions() {
+        const execOptions = super.getDefaultExecOptions();
+        const javaHome = this.compilerProps(`compiler.${this.compiler.id}.java_home`);
+        if (javaHome) {
+            execOptions.env.JAVA_HOME = javaHome;
+        }
+
+        return execOptions;
+    }
+
+    filterUserOptions(userOptions) {
+        // filter options without extra arguments
+        userOptions = userOptions.filter(option =>
+            option !== '-script' && option !== '-progressive' && !option.startsWith('-Xjavac'));
+
+        const oneArgForbiddenList = new Set([
+            // -d directory
+            // Destination for generated class files
+            '-d',
+            // -jdk-home path
+            // Include a custom JDK from the specified location
+            // into the classpath instead of the default JAVA_HOME
+            '-jdk-home',
+            // -kotlin-home path
+            // Path to the home directory of Kotlin compiler used for
+            // discovery of runtime libraries
+            '-kotlin-home',
+        ]);
+
+        // filter options with one argument
+        return super.filterUserOptionsWithArg(userOptions, oneArgForbiddenList);
+    }
+
+    optionsForFilter(filters) {
+        // Forcibly enable javap
+        filters.binary = true;
+
+        return [
+            '-Xjavac-arguments="-Xlint:all"',
+        ];
+    }
+
+    getArgumentParser() {
+        return KotlinParser;
+    }
+}
diff --git a/lib/languages.js b/lib/languages.js
index 57ab9f70e..e77c61961 100644
--- a/lib/languages.js
+++ b/lib/languages.js
@@ -124,6 +124,12 @@ export const languages = {
         extensions: ['.java'],
         alias: [],
     },
+    kotlin: {
+        name: 'Kotlin',
+        monaco: 'kotlin',
+        extensions: ['.kt'],
+        alias: [],
+    },
     ocaml: {
         name: 'OCaml',
         monaco: 'ocaml',
diff --git a/test/kotlin/square/input.kt b/test/kotlin/square/input.kt
new file mode 100644
index 000000000..b1576c436
--- /dev/null
+++ b/test/kotlin/square/input.kt
@@ -0,0 +1,2 @@
+// Type your code here, or load an example.
+fun square(num: Int): Int = num * num
diff --git a/test/kotlin/square/javap-square.asm b/test/kotlin/square/javap-square.asm
new file mode 100644
index 000000000..6512b25fd
--- /dev/null
+++ b/test/kotlin/square/javap-square.asm
@@ -0,0 +1,14 @@
+Compiled from "example.kt"
+public final class ExampleKt {
+  public static final int square(int);
+    Code:
+       0: iload_0
+       1: iload_0
+       2: imul
+       3: ireturn
+    LineNumberTable:
+      line 1: 0
+    LocalVariableTable:
+      Start  Length  Slot  Name   Signature
+          0       4     0   num   I
+}
\ No newline at end of file
diff --git a/test/kotlin/square/output.asm b/test/kotlin/square/output.asm
new file mode 100644
index 000000000..c9c853386
--- /dev/null
+++ b/test/kotlin/square/output.asm
@@ -0,0 +1,11 @@
+public final class ExampleKt {
+  public static final int square(int);
+line 1:      0: iload_0
+line 1:      1: iload_0
+line 1:      2: imul
+line 1:      3: ireturn
+
+    LocalVariableTable:
+      Start  Length  Slot  Name   Signature
+          0       4     0   num   I
+}
\ No newline at end of file
diff --git a/webpack.config.esm.js b/webpack.config.esm.js
index b7ba80068..bf1069fff 100644
--- a/webpack.config.esm.js
+++ b/webpack.config.esm.js
@@ -46,7 +46,7 @@ const staticPath = path.join(distPath, 'static');
 const webjackJsHack = '.v4.';
 const plugins = [
     new MonacoEditorWebpackPlugin({
-        languages: [ 'cpp', 'go', 'pascal', 'python', 'rust', 'swift', 'java' ],
+        languages: [ 'cpp', 'go', 'pascal', 'python', 'rust', 'swift', 'java', 'kotlin' ],
         filename: isDev ? '[name].worker.js' : `[name]${webjackJsHack}worker.[contenthash].js`,
     }),
     new CopyWebpackPlugin([