Multiple fixes of JS source maps

- elvis expression with complex RHS
- destructuring declarations
- decomposition of `var` statement (for example, in case of
  inline destructuring functions)
- `is` LHS &&/|| inline fun RHS
- argument assignment to temporary var on inline call site
- assignment of `next()` result to temporary var in `for` expression
- rethrow statement in exception handler

js/js.inliner/src/org/jetbrains/kotlin/js/inline/ExpressionDecomposer.kt

@@ -81,7 +81,7 @@ internal class ExpressionDecomposer private constructor(
 
         for (jsVar in vars) {
             if (jsVar in containsExtractable && prevVars.isNotEmpty()) {
-                addStatement(JsVars(prevVars, x.isMultiline))
+                addStatement(JsVars(prevVars, x.isMultiline).apply { source = prevVars.first().source })
                 prevVars = SmartList<JsVars.JsVar>()
             }
 
@@ -89,8 +89,11 @@ internal class ExpressionDecomposer private constructor(
             prevVars.add(jsVar)
         }
 
-        vars.clear()
-        vars.addAll(prevVars)
+        if (vars.size != prevVars.size) {
+            vars.clear()
+            vars.addAll(prevVars)
+            x.source = prevVars.first().source
+        }
         return false
     }
 
@@ -168,7 +171,7 @@ internal class ExpressionDecomposer private constructor(
             additionalStatements.toStatement()
         }
 
-        addStatement(JsIf(test, arg2Eval))
+        addStatement(JsIf(test, arg2Eval).also { it.source = source })
         ctx.replaceMe(tmp.nameRef)
     }
 

js/js.inliner/src/org/jetbrains/kotlin/js/inline/FunctionInlineMutator.kt

@@ -50,7 +50,7 @@ private constructor(
         val parameters = getParameters()
 
         removeDefaultInitializers(arguments, parameters, body)
-        aliasArgumentsIfNeeded(namingContext, arguments, parameters)
+        aliasArgumentsIfNeeded(namingContext, arguments, parameters, call.source)
         renameLocalNames(namingContext, invokedFunction)
         processReturns()
 
@@ -89,7 +89,7 @@ private constructor(
         val namingContext = inliningContext.newNamingContext()
         val arguments = call.arguments
         val parameters = outer.parameters
-        aliasArgumentsIfNeeded(namingContext, arguments, parameters)
+        aliasArgumentsIfNeeded(namingContext, arguments, parameters, call.source)
         namingContext.applyRenameTo(inner)
     }
 
@@ -100,7 +100,7 @@ private constructor(
         if (thisReplacement == null || thisReplacement is JsThisRef) return
 
         val thisName = JsScope.declareTemporaryName(getThisAlias())
-        namingContext.newVar(thisName, thisReplacement)
+        namingContext.newVar(thisName, thisReplacement, source = call.source)
         thisReplacement = thisName.makeRef()
 
         replaceThisReference(block, thisReplacement)
@@ -121,7 +121,7 @@ private constructor(
 
         val resultName = JsScope.declareTemporaryName(getResultLabel())
         this.resultName = resultName
-        namingContext.newVar(resultName, null)
+        namingContext.newVar(resultName, source = call.source)
         return resultName.makeRef()
     }
 

js/js.inliner/src/org/jetbrains/kotlin/js/inline/context/NamingContext.kt

@@ -45,9 +45,10 @@ class NamingContext(private val statementContext: JsContext<JsStatement>) {
         renamings.put(name, replacement)
     }
 
-    fun newVar(name: JsName, value: JsExpression? = null) {
+    fun newVar(name: JsName, value: JsExpression? = null, source: Any?) {
         val vars = JsAstUtils.newVar(name, value)
         vars.synthetic = true
+        vars.source = source
         declarations.add(vars)
     }
 }

js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/namingUtils.kt

@@ -25,7 +25,8 @@ import org.jetbrains.kotlin.js.inline.util.rewriters.LabelNameRefreshingVisitor
 fun aliasArgumentsIfNeeded(
         context: NamingContext,
         arguments: List<JsExpression>,
-        parameters: List<JsParameter>
+        parameters: List<JsParameter>,
+        source: Any?
 ) {
     require(arguments.size <= parameters.size) { "arguments.size (${arguments.size}) should be less or equal to parameters.size (${parameters.size})" }
 
@@ -34,9 +35,10 @@ fun aliasArgumentsIfNeeded(
 
         val replacement = JsScope.declareTemporaryName(paramName.ident).apply {
             staticRef = arg
-            context.newVar(this, arg.deepCopy())
+            context.newVar(this, arg.deepCopy(), source = source)
         }.makeRef()
 
+        replacement.source = arg.source
         context.replaceName(paramName, replacement)
     }
 
@@ -45,7 +47,7 @@ fun aliasArgumentsIfNeeded(
         val paramName = defaultParam.name
         val freshName = JsScope.declareTemporaryName(paramName.ident)
         freshName.copyMetadataFrom(paramName)
-        context.newVar(freshName)
+        context.newVar(freshName, source = source)
 
         context.replaceName(paramName, freshName.makeRef())
     }