fix: generate code for receivers outside of block lambdas (#1246)

### Summary of Changes

The code that was generated for the following example was wrong: 

```
rawData.removeRows((row) {
    yield result = row.getValue("age").eq(22).^not();
});
```

The code that was created for `rawData` was inside the body of the
function created for the block lambda. Later references to `rawData`
were, thus, unresolved.

packages/safe-ds-lang/src/language/generation/python/safe-ds-python-generator.ts

@@ -117,6 +117,7 @@ import { SafeDsSlicer } from '../../flow/safe-ds-slicer.js';
 
 const LAMBDA_PREFIX = `${CODEGEN_PREFIX}lambda_`;
 const BLOCK_LAMBDA_RESULT_PREFIX = `${CODEGEN_PREFIX}block_lambda_result_`;
+const PLACEHOLDER_PREFIX = `${CODEGEN_PREFIX}placeholder_`;
 const RECEIVER_PREFIX = `${CODEGEN_PREFIX}receiver_`;
 const YIELD_PREFIX = `${CODEGEN_PREFIX}yield_`;
 
@@ -538,7 +539,7 @@ export class SafeDsPythonGenerator {
                     assignmentStatements.push(
                         expandTracedToNode(
                             savableAssignment,
-                        )`${RUNNER_PACKAGE}.save_placeholder('${savableAssignment.name}', ${CODEGEN_PREFIX}${savableAssignment.name})`,
+                        )`${RUNNER_PACKAGE}.save_placeholder('${savableAssignment.name}', ${PLACEHOLDER_PREFIX}${savableAssignment.name})`,
                     );
                 }
             }
@@ -557,7 +558,7 @@ export class SafeDsPythonGenerator {
                 'name',
             )(assignee.name)}`;
         } else if (isSdsPlaceholder(assignee)) {
-            return expandTracedToNode(assignee)`${CODEGEN_PREFIX}${assignee.name}`;
+            return expandTracedToNode(assignee)`${PLACEHOLDER_PREFIX}${assignee.name}`;
         } else if (isSdsWildcard(assignee)) {
             return traceToNode(assignee)('_');
         } else if (isSdsYield(assignee)) {
@@ -572,7 +573,8 @@ export class SafeDsPythonGenerator {
 
     private generateBlockLambda(blockLambda: SdsBlockLambda, frame: GenerationInfoFrame): Generated {
         const results = streamBlockLambdaResults(blockLambda).toArray();
-        const lambdaBlock = this.generateBlock(blockLambda.body, frame, true);
+        const lambdaFrame = frame.newScope();
+        const lambdaBlock = this.generateBlock(blockLambda.body, lambdaFrame, true);
         if (results.length !== 0) {
             lambdaBlock.appendNewLine();
             lambdaBlock.append(
@@ -815,7 +817,7 @@ export class SafeDsPythonGenerator {
             frame.addImport(referenceImport);
 
             if (isSdsPlaceholder(declaration)) {
-                return traceToNode(expression)(`${CODEGEN_PREFIX}${declaration.name}`);
+                return traceToNode(expression)(`${PLACEHOLDER_PREFIX}${declaration.name}`);
             } else {
                 return traceToNode(expression)(referenceImport?.alias ?? this.getPythonNameOrDefault(declaration));
             }

packages/safe-ds-lang/tests/resources/generation/python/expressions/block lambda/generated/tests/generator/blockLambda/gen_input.py

@@ -23,5 +23,5 @@ def __gen_lambda_3(a, b=2):
     def __gen_lambda_4(a, b=2):
         __gen_block_lambda_result_d = g()
         return __gen_block_lambda_result_d
-    __gen_c = f3(__gen_lambda_4)
-    g2(__gen_c)
+    __gen_placeholder_c = f3(__gen_lambda_4)
+    g2(__gen_placeholder_c)

packages/safe-ds-lang/tests/resources/generation/python/expressions/type casts/generated/tests/generation/expressions/typeCasts/gen_input.py

@@ -1,4 +1,4 @@
 # Segments ---------------------------------------------------------------------
 
 def mySegment(p):
-    __gen_a = p
+    __gen_placeholder_a = p

packages/safe-ds-lang/tests/resources/generation/python/imports/safeds/generated/tests/generator/safeds/gen_input.py

@@ -5,4 +5,4 @@
 # Pipelines --------------------------------------------------------------------
 
 def test():
-    __gen_a = Table()
+    __gen_placeholder_a = Table()

packages/safe-ds-lang/tests/resources/generation/python/macros/any/generated/tests/generation/python/macros/strings/gen_input.py

@@ -2,6 +2,6 @@
 
 def myPipeline():
     __gen_receiver_0 = 'Hello, world!'
-    __gen_toBoolean = (bool((__gen_receiver_0)))
+    __gen_placeholder_toBoolean = (bool((__gen_receiver_0)))
     __gen_receiver_1 = 'Hello, world!'
-    __gen_toString = (str((__gen_receiver_1)))
+    __gen_placeholder_toString = (str((__gen_receiver_1)))

packages/safe-ds-lang/tests/resources/generation/python/macros/strings/generated/tests/generation/python/macros/strings/gen_input.py

@@ -2,38 +2,38 @@
 
 def myPipeline():
     __gen_receiver_0 = 'Hello, world!'
-    __gen_contains = (('world') in (__gen_receiver_0))
+    __gen_placeholder_contains = (('world') in (__gen_receiver_0))
     __gen_receiver_1 = 'Hello, world!'
-    __gen_endsWith = ((__gen_receiver_1).endswith(('world!')))
+    __gen_placeholder_endsWith = ((__gen_receiver_1).endswith(('world!')))
     __gen_receiver_2 = 'Hello, world!'
-    __gen_indexOf = ((__gen_receiver_2).find(('o')))
+    __gen_placeholder_indexOf = ((__gen_receiver_2).find(('o')))
     __gen_receiver_3 = 'Hello, world!'
-    __gen_lastIndexOf = ((__gen_receiver_3).rfind(('o')))
+    __gen_placeholder_lastIndexOf = ((__gen_receiver_3).rfind(('o')))
     __gen_receiver_4 = 'Hello, world!'
-    __gen_length = (len((__gen_receiver_4)))
+    __gen_placeholder_length = (len((__gen_receiver_4)))
     __gen_receiver_5 = 'Hello, world!'
-    __gen_repeat = ((__gen_receiver_5) * (2))
+    __gen_placeholder_repeat = ((__gen_receiver_5) * (2))
     __gen_receiver_6 = 'Hello, world!'
-    __gen_replace = ((__gen_receiver_6).replace(('world'), ('planet')))
+    __gen_placeholder_replace = ((__gen_receiver_6).replace(('world'), ('planet')))
     __gen_receiver_7 = 'Hello, world!'
-    __gen_split = ((__gen_receiver_7).split((', ')))
+    __gen_placeholder_split = ((__gen_receiver_7).split((', ')))
     __gen_receiver_8 = 'Hello, world!'
-    __gen_startsWith = ((__gen_receiver_8).startswith(('Hello')))
+    __gen_placeholder_startsWith = ((__gen_receiver_8).startswith(('Hello')))
     __gen_receiver_9 = 'Hello, world!'
-    __gen_substring = ((__gen_receiver_9)[(7):()])
+    __gen_placeholder_substring = ((__gen_receiver_9)[(7):()])
     __gen_receiver_10 = 'Hello, world!'
-    __gen_casefolded = ((__gen_receiver_10).casefold())
+    __gen_placeholder_casefolded = ((__gen_receiver_10).casefold())
     __gen_receiver_11 = '3.14'
-    __gen_float = (float((__gen_receiver_11)))
+    __gen_placeholder_float = (float((__gen_receiver_11)))
     __gen_receiver_12 = '42'
-    __gen_int = (int((__gen_receiver_12), ()))
+    __gen_placeholder_int = (int((__gen_receiver_12), ()))
     __gen_receiver_13 = 'Hello, world!'
-    __gen_lowercase = ((__gen_receiver_13).lower())
+    __gen_placeholder_lowercase = ((__gen_receiver_13).lower())
     __gen_receiver_14 = 'Hello, world!'
-    __gen_uppercase = ((__gen_receiver_14).upper())
+    __gen_placeholder_uppercase = ((__gen_receiver_14).upper())
     __gen_receiver_15 = '  Hello, world!  '
-    __gen_trimmed = ((__gen_receiver_15).strip())
+    __gen_placeholder_trimmed = ((__gen_receiver_15).strip())
     __gen_receiver_16 = '  Hello, world!  '
-    __gen_trimmedEnd = ((__gen_receiver_16).rstrip())
+    __gen_placeholder_trimmedEnd = ((__gen_receiver_16).rstrip())
     __gen_receiver_17 = '  Hello, world!  '
-    __gen_trimmedStart = ((__gen_receiver_17).lstrip())
+    __gen_placeholder_trimmedStart = ((__gen_receiver_17).lstrip())

packages/safe-ds-lang/tests/resources/generation/python/partial/impure dependency file constant/generated/tests/generator/partialImpureDependencyFileConstant/gen_input.py

@@ -5,10 +5,10 @@
 # Pipelines --------------------------------------------------------------------
 
 def testPipeline():
-    __gen_impureFileWrite = iFileWriteA()
-    __gen_impureFileWrite2 = iFileWriteA()
-    __gen_impureFileReadAgain = iFileReadA()
-    __gen_impureFileWriteB = iFileWriteB()
-    __gen_impureFileWrite2B = iFileWriteB()
-    __gen_impureFileReadAgainB = iFileReadB()
-    __gen_result = (__gen_impureFileReadAgain) + (__gen_impureFileReadAgainB)
+    __gen_placeholder_impureFileWrite = iFileWriteA()
+    __gen_placeholder_impureFileWrite2 = iFileWriteA()
+    __gen_placeholder_impureFileReadAgain = iFileReadA()
+    __gen_placeholder_impureFileWriteB = iFileWriteB()
+    __gen_placeholder_impureFileWrite2B = iFileWriteB()
+    __gen_placeholder_impureFileReadAgainB = iFileReadB()
+    __gen_placeholder_result = (__gen_placeholder_impureFileReadAgain) + (__gen_placeholder_impureFileReadAgainB)

packages/safe-ds-lang/tests/resources/generation/python/partial/impure dependency file parameter/generated/tests/generator/partialImpureDependencyFileParameter/gen_input.py

@@ -5,7 +5,7 @@
 # Pipelines --------------------------------------------------------------------
 
 def testPipeline():
-    __gen_impureFileWrite = iFileWrite('b.txt')
-    __gen_impureFileWrite2 = iFileWrite('c.txt')
-    __gen_impureFileReadAgain = iFileRead('d.txt')
-    __gen_result = (__gen_impureFileReadAgain) + (2)
+    __gen_placeholder_impureFileWrite = iFileWrite('b.txt')
+    __gen_placeholder_impureFileWrite2 = iFileWrite('c.txt')
+    __gen_placeholder_impureFileReadAgain = iFileRead('d.txt')
+    __gen_placeholder_result = (__gen_placeholder_impureFileReadAgain) + (2)

packages/safe-ds-lang/tests/resources/generation/python/partial/impure dependency/generated/tests/generator/partialImpureDependency/gen_input.py

@@ -6,17 +6,17 @@
 
 def testPipeline():
     i1(1)
-    __gen_impureFileWrite = iFileWrite()
-    __gen_impureFileWrite2 = iFileWrite()
-    __gen_pureValueForImpure2 = noPartialEvalInt(2)
-    __gen_pureValueForImpure3 = 3
+    __gen_placeholder_impureFileWrite = iFileWrite()
+    __gen_placeholder_impureFileWrite2 = iFileWrite()
+    __gen_placeholder_pureValueForImpure2 = noPartialEvalInt(2)
+    __gen_placeholder_pureValueForImpure3 = 3
     def __gen_lambda_0():
         i1(1)
         __gen_block_lambda_result_r = 1
         return __gen_block_lambda_result_r
     fp(__gen_lambda_0)
     i1(1)
-    __gen_impureA1 = i1(__gen_pureValueForImpure2)
-    __gen_impureA2 = i1(noPartialEvalInt(3))
+    __gen_placeholder_impureA1 = i1(__gen_placeholder_pureValueForImpure2)
+    __gen_placeholder_impureA2 = i1(noPartialEvalInt(3))
     i1(4)
-    __gen_result = i1(__gen_impureA2)
+    __gen_placeholder_result = i1(__gen_placeholder_impureA2)

packages/safe-ds-lang/tests/resources/generation/python/partial/pure dependency/generated/tests/generator/partialPureDependency/gen_input.py

@@ -5,30 +5,30 @@
 # Pipelines --------------------------------------------------------------------
 
 def testPipeline():
-    __gen_lFalse = False
-    __gen_lDouble = -1.0
-    __gen_lInt = 1
-    __gen_lNull = None
-    __gen_lStrMulti = 'multi\nline'
-    __gen_boolean1 = True
-    __gen_value1 = g(True, -1.0, 1, None, 'multi\nline')
+    __gen_placeholder_lFalse = False
+    __gen_placeholder_lDouble = -1.0
+    __gen_placeholder_lInt = 1
+    __gen_placeholder_lNull = None
+    __gen_placeholder_lStrMulti = 'multi\nline'
+    __gen_placeholder_boolean1 = True
+    __gen_placeholder_value1 = g(True, -1.0, 1, None, 'multi\nline')
     def __gen_lambda_0():
-        __gen_i = 1
-        __gen_i2 = 3
-        __gen_j = 6
-        __gen_j2 = 4
+        __gen_placeholder_i = 1
+        __gen_placeholder_i2 = 3
+        __gen_placeholder_j = 6
+        __gen_placeholder_j2 = 4
         __gen_block_lambda_result_z = 7
         return __gen_block_lambda_result_z
     def __gen_lambda_1():
         return 2
-    __gen_o = (f(__gen_lambda_0)) + (f(__gen_lambda_1))
-    __gen_mapKey = 'key'
-    __gen_mapValue = 'value'
-    __gen_mapResult = g2({'key': 'value'})
-    __gen_listV1 = 1
-    __gen_listV3 = noPartialEvalInt(1)
-    __gen_list = [1]
-    __gen_list3 = [__gen_listV3]
-    __gen_listValue = __gen_list3[0]
-    __gen_listResult = g3(__gen_list)
-    __gen_result = (((-(__gen_o)) + (1)) + (__gen_value1)) + (((__gen_mapResult) * (__gen_listResult)) / (g4(__gen_listValue)))
+    __gen_placeholder_o = (f(__gen_lambda_0)) + (f(__gen_lambda_1))
+    __gen_placeholder_mapKey = 'key'
+    __gen_placeholder_mapValue = 'value'
+    __gen_placeholder_mapResult = g2({'key': 'value'})
+    __gen_placeholder_listV1 = 1
+    __gen_placeholder_listV3 = noPartialEvalInt(1)
+    __gen_placeholder_list = [1]
+    __gen_placeholder_list3 = [__gen_placeholder_listV3]
+    __gen_placeholder_listValue = __gen_placeholder_list3[0]
+    __gen_placeholder_listResult = g3(__gen_placeholder_list)
+    __gen_placeholder_result = (((-(__gen_placeholder_o)) + (1)) + (__gen_placeholder_value1)) + (((__gen_placeholder_mapResult) * (__gen_placeholder_listResult)) / (g4(__gen_placeholder_listValue)))

packages/safe-ds-lang/tests/resources/generation/python/partial/redundant impurity/generated/tests/generator/partialRedundantImpurity/gen_input.py

@@ -5,5 +5,5 @@
 # Pipelines --------------------------------------------------------------------
 
 def testPipeline():
-    __gen_pureValue = noPartialEvalInt(2)
-    __gen_result = (__gen_pureValue) - (1)
+    __gen_placeholder_pureValue = noPartialEvalInt(2)
+    __gen_placeholder_result = (__gen_placeholder_pureValue) - (1)