ported SketchWithMultilineTemplate from legacy into integration test

internal/integrationtest/compile_4/compile_test.go

@@ -111,6 +111,7 @@ func TestCompileOfProblematicSketches(t *testing.T) {
 		{"SketchWithExternC", testBuilderSketchWithExternC},
 		{"SketchWithMultilinePrototypes", testBuilderSketchWithMultilinePrototypes},
 		{"SketchWithExternCMultiline", testBuilderSketchWithExternCMultiline},
+		{"SketchWithMultilineTemplate", testBuilderSketchWithMultilineTemplate},
 	}.Run(t, env, cli)
 }
 
@@ -709,6 +710,21 @@ func testBuilderSketchWithExternCMultiline(t *testing.T, env *integrationtest.En
 	})
 }
 
+func testBuilderSketchWithMultilineTemplate(t *testing.T, env *integrationtest.Environment, cli *integrationtest.ArduinoCLI) {
+	t.Run("Build", func(t *testing.T) {
+		// Build
+		_, err := tryBuild(t, env, cli, "arduino:avr:leonardo")
+		require.NoError(t, err)
+	})
+
+	t.Run("Preprocess", func(t *testing.T) {
+		// Preprocess
+		sketchPath, preprocessedSketch, err := tryPreprocess(t, env, cli, "arduino:avr:leonardo")
+		require.NoError(t, err)
+		comparePreprocessGoldenFile(t, sketchPath, preprocessedSketch)
+	})
+}
+
 type builderOutput struct {
 	CompilerOut   string `json:"compiler_out"`
 	CompilerErr   string `json:"compiler_err"`

internal/integrationtest/compile_4/testdata/SketchWithMultilineTemplate/SketchWithMultilineTemplate.preprocessed.txt

@@ -0,0 +1,20 @@
+#include <Arduino.h>
+#line 0 "{{QuoteCppString .sketchMainFile}}"
+template< typename T >  T func(T t);
+#line 6 "{{QuoteCppString .sketchMainFile}}"
+void setup();
+#line 10 "{{QuoteCppString .sketchMainFile}}"
+void loop();
+#line 0 "{{QuoteCppString .sketchMainFile}}"
+#line 1 "{{QuoteCppString .sketchMainFile}}"
+template< typename T >  
+T func(T t){
+    return t * t;
+}
+
+void setup() {
+  func( 12.34f );
+}
+
+void loop() {}
+