Compilation failures caused by code from previous sketch after "Save As"

ptillisch · August 24, 2025, 7:36pm

Hi @ravenable. Can you provide a detailed set of step-by-step minimal instructions we can follow to reproduce the fault?

It sounds somewhat like this known bug:

github.com/arduino/arduino-cli

Previous file persists in build folder after renaming non-`.ino` sketch code file

opened 11:18PM - 19 Jun 16 UTC

digimeas

topic: code type: imperfection topic: build-process

### Describe the problem The previous file persists in the sketch build folder …after a sketch code file with extension other than `.ino`/`.pde` is renamed. 🐛 This can result in spurious compilation errors or confusing bugs. Arduino CLI users can work around the bug by adding the `--clean` flag to their command, but the only workaround for Arduino IDE users is to manually clean the build folder. ### To reproduce ```text $ arduino-cli version arduino-cli.exe Version: git-snapshot Commit: a735ddfd Date: 2023-01-15T01:00:07Z $ arduino-cli sketch new /tmp/FooSketch $ echo "void asdf() {}" > /tmp/FooSketch/foo.cpp $ arduino-cli compile --fqbn arduino:avr:uno /tmp/FooSketch [...] $ mv /tmp/FooSketch/foo.cpp /tmp/FooSketch/bar.cpp $ arduino-cli compile --fqbn arduino:avr:uno /tmp/FooSketch C:\Users\per\AppData\Local\Temp\arduino\sketch-2405C4C9F90028537C79B0744BCE536E\sketch\foo.cpp.o (symbol from plugin): In function `asdf()': (.text+0x0): multiple definition of `asdf()' C:\Users\per\AppData\Local\Temp\arduino\sketch-2405C4C9F90028537C79B0744BCE536E\sketch\bar.cpp.o (symbol from plugin):(.text+0x0): first defined here collect2.exe: error: ld returned 1 exit status Used platform Version Path arduino:avr 1.8.6 C:\Users\per\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.6 Error during build: exit status 1 $ ls "C:/Users/per/AppData/Local/Temp/arduino/sketch-2405C4C9F90028537C79B0744BCE536E/sketch" bar.cpp bar.cpp.d bar.cpp.o foo.cpp foo.cpp.d foo.cpp.o FooSketch.ino.cpp FooSketch.ino.cpp.d FooSketch.ino.cpp.o ``` 🐛 `foo.cpp` is still present in the build folder even though not present in the sketch. `foo.cpp` is compiled in addition to `bar.cpp` and the primary sketch file. ### Expected behavior Files are always removed from the sketch build folder when no longer present in the sketch. ### Arduino CLI version #### Original report Arduino IDE 1.6.9 #### Last verified with 0.34.1 ### Operating system - Linux - Windows ### Operating system version - Mint - 10 ### Additional context #### Workaround <a name="workaround-cli"></a> ##### Arduino CLI users Run an `arduino-cli compile` command with [the `--clean` flag](https://arduino.github.io/arduino-cli/dev/commands/arduino-cli_compile/#options). <a name="workaround-ide"></a> ##### Arduino IDE users 1. Examine the compiler error message. It will show the path of the temporary build folder. For example, in this error: ```text C:\Users\per\AppData\Local\Temp\arduino\sketches\7930E8409AED6D4F4A4782CF985194E9\sketch\foo.cpp.o (symbol from plugin): In function `asdf()': (.text+0x0): multiple definition of `asdf()' C:\Users\per\AppData\Local\Temp\arduino\sketches\7930E8409AED6D4F4A4782CF985194E9\sketch\bar.cpp.o (symbol from plugin):(.text+0x0): first defined here collect2.exe: error: ld returned 1 exit status exit status 1 Compilation error: exit status 1 ``` The temporary build folder is: ```text C:\Users\per\AppData\Local\Temp\arduino\sketches\7930E8409AED6D4F4A4782CF985194E9\sketch\ ``` 1. Delete the temporary build folder. #### Additional reports - https://github.com/arduino/arduino-cli/issues/1699 - https://github.com/arduino/arduino-cli/issues/2058 - https://github.com/arduino/arduino-cli/issues/2613 - https://github.com/arduino/arduino-cli/issues/2870 - https://github.com/arduino/arduino-ide/issues/970 - https://github.com/arduino/arduino-ide/issues/1316 - https://github.com/arduino/arduino-ide/issues/1691 - https://github.com/arduino/arduino-ide/issues/2323 - https://github.com/arduino/arduino-ide/issues/482#issuecomment-2188269824 - https://github.com/arduino/Arduino/issues/2072 - https://forum.arduino.cc/t/ide-and-compiler-clear/1077526 - https://forum.arduino.cc/t/changed-tab-name-in-sketch-still-linking-old-o-file/1046286 - https://forum.arduino.cc/t/weird-error-pointing-to-old-code/1113608 - https://forum.arduino.cc/t/ide2-bit-upset-need-help/1129513 - https://forum.arduino.cc/t/renamed-tabs-wont-go-away/1165338 - https://forum.arduino.cc/t/file-renaming-issue/1173234/6 - https://forum.arduino.cc/t/reorganizing-code-w-wire-h-library/1180211 - https://forum.arduino.cc/t/ide-not-recognising-file-type-change-from-c-to-cpp/1215993 - https://forum.arduino.cc/t/code-compiles-in-old-ide-but-not-the-new-one/1286767 - https://forum.arduino.cc/t/problem-while-defining-namespaces-with-it-own-cpp-and-hpp-files/1304403 - https://forum.arduino.cc/t/there-is-a-bug-in-the-wire-library-for-version-1-8-6-avr-boards/1336297/18 - https://forum.arduino.cc/t/new-version-of-arduino-ide-2-3-5-error/1371224/20 - https://forum.arduino.cc/t/how-to-clear-cache-from-ide/1374114 - https://forum.arduino.cc/t/ld-problems-with-multiple-source-files/1381506/6 - https://forum.arduino.cc/t/how-to-clear-cache-from-ide/1374114/12 --- <details> <summary><b>Keywords</b></summary> <p> - rename - header - .h - .cpp - .c - C++ </p> </details> ### Issue checklist - [X] I searched for previous reports in [the issue tracker](https://github.com/arduino/arduino-ide/issues?q=) - [X] I verified the problem still occurs when using the latest [nightly build](https://www.arduino.cc/en/software#nightly-builds) - [X] My report contains all necessary details

However, that is not known to be caused by a "Save As..." operation, so I'm not certain.

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Compilation failures caused by code from previous sketch after "Save As"

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