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CFR, Fernflower, Vineflower: No line numbers available in class file #118
Description
Version 3.5.1, Eclipse 4.36.0
I'm checking org.slf4j.Logger from slf4j-api-2.0.7.jar.
Unless I choose "JD Core" or "Procyon", there's the comment at the beginning of decompiled class:
// Warning: No line numbers available in class file
Yet, with CFR or Fernflower the line numbers are there!
default boolean isEnabledForLevel(Level level) {
int levelInt = level.toInt();// 146
switch (levelInt) {// 147
case 0:
return this.isTraceEnabled();// 149
case 10:
return this.isDebugEnabled();// 151
case 20:
return this.isInfoEnabled();// 153
case 30:
return this.isWarnEnabled();// 155
case 40:
return this.isErrorEnabled();// 157
default:
throw new IllegalArgumentException("Level [" + level + "] not recognized.");// 159
}
}
With Vineflower there are no line number comments at all.
With JD Core or Procyon it still works:
/* */ default boolean isEnabledForLevel(Level level) {
/* 146 */ int levelInt = level.toInt();
/* 147 */ switch (levelInt) {
/* */ case 0:
/* 149 */ return isTraceEnabled();
/* */ case 10:
/* 151 */ return isDebugEnabled();
/* */ case 20:
/* 153 */ return isInfoEnabled();
/* */ case 30:
/* 155 */ return isWarnEnabled();
/* */ case 40:
/* 157 */ return isErrorEnabled();
/* */ }
/* 159 */ throw new IllegalArgumentException("Level [" + level + "] not recognized.");
/* */ }
Activity
jpstotz commentedon Jul 5, 2025
This is because CFR and Fernflower do not support to output source code aligned to the line numbers from debug info. They only output line numbers in a format that is not detected by ECD.
zilibaba commentedon Oct 9, 2025
I just have updated to Eclipse 2025-06 from Eclipse 2023-06. Line alignment for CFR and Fernflower work well in 2023-6 (ECD 3.3.0), however doesn't work in 2025-6 (ECD 3.5.1). What can I do to assist in issue handling?
jpstotz commentedon Oct 11, 2025
@zilibaba Do you use the Debug or Java perspective? Also it would be important to know what ECD settings you have configured (see Eclipse preferences Java -> Decompiler).
zilibaba commentedon Oct 11, 2025
@jpstotz Debug and Java perspectives both works simultaneously and have same behavior. ECD settings identical on both machines:
nbauma109 commentedon Nov 16, 2025
Unifying display of line numbers inside a left margin was a feature that was originally supported in upstream project.
https://github.com/cpupk/ecd/blob/ba76decd895f15513d151cd52bfd8ecdf14f2fd0/org.sf.feeling.decompiler/src/org/sf/feeling/decompiler/util/DecompilerOutputUtil.java#L439-L442
This code was removed somehow.
I remember supporting it for both FernFlower/VineFlower as they output line numbers the same way.
https://github.com/nbauma109/ecd/blob/57de1fcc09b773eadc3f0e6a189381ec6d6a9299/org.sf.feeling.decompiler/src/org/sf/feeling/decompiler/util/DecompilerOutputUtil.java#L361-L366
Once line numbers are moved to the left margin, ECD does a best-effort post-process to realign line numbers for debugging.
jpstotz commentedon Nov 16, 2025
@nbauma109 I just checked it: For FernFlower it seems that the DecompilerOutputUtil expects a certain format how the line numbers are included in the source code. This format is only indirectly documented by the used Regex. By updating FernFlower the comment format has changed and thus DecompilerOutputUtil is no longer able to identify the line numbers.
The complete reformat process has next to no documentation and doesn't seem to be really decompiler specific. IMHO this process needs to be updated, so that each decompiler instance also provides the code (or regex?) for extracting the line numbers. And even more important the whole process needs to be documented well.
jpstotz commentedon Nov 23, 2025
@nbauma109 I pushed my latest work that changed a lot regarding the reformatting process to branch https://github.com/ecd-plugin/ecd/tree/reformat
In my tests this version looked quite good. You any anybody else feel free to give it a test.
nbauma109 commentedon Nov 23, 2025
test ok on my end !
basinilya commentedon Nov 28, 2025
Side question: I want to install from the just built update site zip
update_site/target/com.github.ecd-plugin.update-3.5.1.zip. I uninstalled the existing version using the "Installed software" tab but the old jars 3.5.1 from 2024 are still in my plugins folder and installing from disk doesn't replace them. If I delete these jars manually then the next install attempt fails with:jpstotz commentedon Nov 28, 2025
@basinilya Have you cleaned the "Installation History" of Eclipse (see About -> Installation Details -> tab Installation History). There Eclipse records al the installation changes and unless the old configurations that make use of the ECD jars are deleted Eclipse may try to access plugins that are referenced there.
In the end it might be easier changing the ECD version. See the scripts
update-versionfor Linux/Windows in the project root folder.