Templated files are NOT processed independently of each other

[paltherr]

Describe the bug

Any modification to the . dictionary done while processing a templated file is visible in the processing of further templated files. The processing of each templated file should start with an unmodified . dictionary.

To reproduce

File chezmoi/.chezmoitemplates/file.txt:

home={{ .chezmoi.homeDir }}
name={{ .filename }}.txt

File chezmoi/file1.txt.tmpl:

{{- template "file.txt" (merge . (dict "filename" "file1")) -}}

File chezmoi/file2.txt.tmpl:

{{- template "file.txt" (merge . (dict "filename" "file2")) -}}

$ chezmoi apply file1.txt file2.txt
$ tail -1 file1.txt
name=file1.txt
$ tail -1 file2.txt
name=file1.txt

Note that file2.txt contains file1.

$ chezmoi apply file2.txt  
$ tail -1 file2.txt      
name=file2.txt

Nowfile2.txt contains file2.

% chezmoi apply          
paltherr@maloja ~ % tail -1 file2.txt
name=file1.txt

And it's back to file1!?!

Expected behavior

The file file2.txt should always contain file2.

Output of chezmoi doctor

```console $ chezmoi doctor RESULT CHECK MESSAGE ok version v2.35.2, commit 44814515eb8034b4d153569db86e58e278148e05, built at 2023-07-19T08:02:28Z, built by Homebrew warning latest-version v2.36.0 ok os-arch darwin/amd64 ok uname Darwin maloja 22.5.0 Darwin Kernel Version 22.5.0: Mon Apr 24 20:51:50 PDT 2023; root:xnu-8796.121.2~5/RELEASE_X86_64 x86_64 ok go-version go1.20.6 (gc) ok executable /usr/local/bin/chezmoi ok upgrade-method replace-executable ok config-file ~/.config/chezmoi/chezmoi.toml, last modified 2023-07-28T21:23:59+02:00 ok source-dir ~/account-customization/chezhome is a directory warning suspicious-entries ~/account-customization/chezhome/.chezmoitemplates/chezmoi.toml, ~/account-customization/chezhome/dot_config/chezmoi/private_chezmoi.toml.tmpl, ~/account-customization/chezhome/dot_config/chezroot/private_chezmoi.toml.tmpl, and ~/account-customization/chezhome/private_Library/private_Preferences/.chezmoiignore~ warning working-tree ~/account-customization is a git working tree (dirty) ok dest-dir ~ is a directory ok umask 022 ok cd-command found /bin/zsh ok cd-args /bin/zsh info diff-command not set ok edit-command found /usr/local/bin/emacs ok edit-args emacs ok git-command found /usr/local/bin/git, version 2.41.0 ok merge-command found /usr/bin/vimdiff ok shell-command found /bin/zsh ok shell-args /bin/zsh info age-command age not found in $PATH info gpg-command gpg not found in $PATH info pinentry-command not set info 1password-command op not found in $PATH info bitwarden-command bw not found in $PATH info dashlane-command dcli not found in $PATH info gopass-command gopass not found in $PATH info keepassxc-command keepassxc-cli not found in $PATH info keepassxc-db not set info keeper-command keeper not found in $PATH info lastpass-command lpass not found in $PATH info pass-command pass not found in $PATH info passhole-command ph not found in $PATH info rbw-command rbw not found in $PATH info vault-command vault not found in $PATH info vlt-command vlt not found in $PATH info secret-command not set ```

[paltherr]

Note that I found that I could avoid the problem by switching the order of the two merge arguments in the .tmpl files. However, it still looks wrong that modifying . in one .tmpl file may affect the processing of other .tmpl files.

[twpayne]

This is because you are using the merge template function. According to the documentation:

merge, mustMerge

Merge two or more dictionaries into one, giving precedence to the dest dictionary:

$newdict := merge $dest $source1 $source2

This is a deep merge operation but not a deep copy operation. Nested objects that are merged are the same instance on both dicts. If you want a deep copy along with the merge than use the deepCopy function along with merging. For example,

deepCopy $source | merge $dest

mustMerge will return an error in case of unsuccessful merge.

You need to use deepCopy.

[paltherr]

Sure, that avoids the problem but isn't it problematic that chezmoi generates different results for the same target depending on which files it's applied to? With my example, running chezmoi apply file1.txt file2.txt generates a file2.txt that contains file1 and running chezmoi apply file2.txt generates a file2.txt that contains file2. Shouldn't chezmoi always generate the same result for the same target? Couldn't it achieve that by processing each file with a preventive deepCopy of .?

Users could still shoot themselves in the foot, for example by calling two templates with . where the first template modifies . and thus impacts the second template. But at least chezmoi would then be self-consistent and always generate the same result for a given target.

[twpayne]

You're right. The template execution should be independent. Should be fixed with #3129. Thank you for spotting and reporting this :)