fix(linker): Avoid filename clashes when linking (PLC-lang#1086)

Append .o extension to end of file name instead of replacing previous extension

compiler/plc_driver/src/pipelines.rs

@@ -312,7 +312,7 @@ impl AnnotatedProject {
                         let current_dir = env::current_dir()?;
                         let current_dir = compile_options.root.as_deref().unwrap_or(&current_dir);
                         let unit_location = PathBuf::from(&unit.file_name);
-                        let unit_location = std::fs::canonicalize(unit_location)?;
+                        let unit_location = fs::canonicalize(unit_location)?;
                         let output_name = if unit_location.starts_with(current_dir) {
                             unit_location.strip_prefix(current_dir).map_err(|it| {
                                 Diagnostic::error(format!(
@@ -329,9 +329,9 @@ impl AnnotatedProject {
                         };
 
                         let output_name = match compile_options.output_format {
-                            FormatOption::IR => output_name.with_extension("ll"),
-                            FormatOption::Bitcode => output_name.with_extension("bc"),
-                            _ => output_name.with_extension("o"),
+                            FormatOption::IR => format!("{}.ll", output_name.to_string_lossy()),
+                            FormatOption::Bitcode => format!("{}.bc", output_name.to_string_lossy()),
+                            _ => format!("{}.o", output_name.to_string_lossy()),
                         };
 
                         let context = CodegenContext::create(); //Create a build location for the generated object files
@@ -340,7 +340,7 @@ impl AnnotatedProject {
                         module
                             .persist(
                                 Some(&compile_directory),
-                                &output_name.to_string_lossy(),
+                                &output_name,
                                 compile_options.output_format,
                                 target,
                                 compile_options.optimization,

tests/integration/data/linking/consts.st

@@ -1,3 +1,6 @@
 VAR_GLOBAL CONSTANT
     myValue : BOOL := TRUE;
 END_VAR
+
+FUNCTION main : DINT
+END_FUNCTION

tests/integration/linking.rs

@@ -225,3 +225,15 @@ fn link_files_with_same_name() {
     //Delete it
     fs::remove_file(&out1).unwrap();
 }
+
+#[test]
+fn link_files_with_same_name_but_different_extension() {
+    let file1 = get_test_file("linking/consts.st");
+    let file2 = get_test_file("linking/consts.dt");
+
+    // We want to make sure that generating object files for two or more files with the same name but different
+    // extensions works. Previously this would fail because both `const.st` and `const.dt` would persist to a
+    // `const.o` file, which causes linking issues and more specifically "duplicate symbol" errors. Hence we only
+    // check whether the compilation resulted in some Ok value here.
+    assert!(compile(&["plc", file1.as_str(), file2.as_str(), "--target", TARGET.unwrap()]).is_ok());
+}