[clang-format] Fix working -assume-filename with .clang-format-ignore

[kakkoko]

Fixes #113099.

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[llvmbot]

@llvm/pr-subscribers-clang-format

Author: kakkoko (kakkoko)

Changes

Fixes #113099.

---

Full diff: https://github.com/llvm/llvm-project/pull/113100.diff

2 Files Affected:

• (modified) clang/test/Format/clang-format-ignore.cpp (+11)
• (modified) clang/tools/clang-format/ClangFormat.cpp (+7-1)

diff --git a/clang/test/Format/clang-format-ignore.cpp b/clang/test/Format/clang-format-ignore.cpp
index fb49fa9dd52c65..198ef3200a3845 100644
--- a/clang/test/Format/clang-format-ignore.cpp
+++ b/clang/test/Format/clang-format-ignore.cpp
@@ -46,5 +46,16 @@
 // CHECK5-NEXT: {{Formatting \[4/5] .*foo\.c}}
 // CHECK5-NOT: foo.js
 
+// RUN: echo "foo.*" > .clang-format-ignore
+// RUN: touch foo.c
+// RUN: echo foo | clang-format -assume-filename=foo.c 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK6 -allow-empty
+// CHECK6-NOT: foo
+
+// RUN: touch bar.c
+// RUN: echo foo | clang-format -assume-filename=bar.c 2>&1 \
+// RUN:   | FileCheck %s -check-prefix=CHECK7 -allow-empty
+// CHECK7: foo
+
 // RUN: cd ..
 // RUN: rm -r %t.dir
diff --git a/clang/tools/clang-format/ClangFormat.cpp b/clang/tools/clang-format/ClangFormat.cpp
index 108db7204aa68a..c31f3d97f17eb1 100644
--- a/clang/tools/clang-format/ClangFormat.cpp
+++ b/clang/tools/clang-format/ClangFormat.cpp
@@ -707,8 +707,14 @@ int main(int argc, const char **argv) {
     errs() << "Clang-formatting " << LineNo << " files\n";
   }
 
-  if (FileNames.empty())
+  if (FileNames.empty()) {
+    if (!AssumeFileName.empty() && isIgnored(AssumeFileName)) {
+      outs() << "ignored\n";
+      return 0;
+    }
+    outs() << "not ignored\n";
     return clang::format::format("-", FailOnIncompleteFormat);
+  }
 
   if (FileNames.size() > 1 &&
       (!Offsets.empty() || !Lengths.empty() || !LineRanges.empty())) {

[github-actions[bot]]

:white_check_mark: With the latest revision this PR passed the C/C++ code formatter.

[owenca]

Also, the main purpose of -assume-filename is to set the language for input from stdin, and IMO the pseudo filename should not be filtered out by any .clang-format-ignore file.

[kakkoko]

Also, the main purpose of -assume-filename is to set the language for input from stdin, and IMO the pseudo filename should not be filtered out by any .clang-format-ignore file.

It is also worth noting that if the -style=file option is specified, it will look for .clang-format/_clang-format file in the same or parent directory based on the pathname specified by the -assume-filename option.

Since the specification is such for .clang-format/_clang-format file, users would naturally expect the same behavior for .clang-format-ignore file, wouldn't they?

[kakkoko]

I get what you are doing here, simply passing the input to the output even if we've said ignore the file.. Its not that I don't think this is ok I'm just wondering why the fix is here and not in the VS Code extension.

Sorry. This was my mistake. I had misconfigured some settings. The VSCode extension worked perfectly even when clang-format outputs nothing.

Therefore, I replaced the commit with a very simple one.

[mydeveloperday]

Also, the main purpose of -assume-filename is to set the language for input from stdin, and IMO the pseudo filename should not be filtered out by any .clang-format-ignore file.

It is also worth noting that if the -style=file option is specified, it will look for .clang-format/_clang-format file in the same or parent directory based on the pathname specified by the -assume-filename option.

Since the specification is such for .clang-format/_clang-format file, users would naturally expect the same behavior for .clang-format-ignore file, wouldn't they?

I'm a little confused..

So it seems you are saying... that an IDE that is using clang-format, formats the contents of the editor using stdin to clang-format, sort of like

echo "editor_buffer" | clang-format 

and because it knows editor_buffer came from c:/project/myproject/src/lib/myfile.cxx its passing

echo "editor_buffer" | clang-format --assume-filename c:/project/myproject/src/lib/myfile.cxx

I presume in both case the IDE reads the output and puts it back in the editor rather than writing it to the file incase the user isn't ready to save just yet.

which means if you are running with --stage=file its using that assume-filename to get the directory of that assume-file and then look up that tree for a .clang-format

echo "buffer" | clang-format --style=file --assume-filename c:/project/myproject/src/lib/myfile.cxx

However what you are saying is, its not using that assume-filename to locate the .clang-format-ignore file? which if it had might have seen that myfile.* should have been ignored.

Hence in the IDE it reformats myfile.* meaning you can't save it unformatted

Did I understand that correctly? (its likely exactly what you said...)

[kakkoko]

@mydeveloperday

However what you are saying is, its not using that assume-filename to locate the .clang-format-ignore file?

Hence in the IDE it reformats myfile.* meaning you can't save it unformatted

Yes, that is correct.

You can see that in the following file of Clang-Format.cpp, main():

  // If no file name is specified on the command line to be processed,
  // formatting is performed on standard input and terminates.
  if (FileNames.empty())
    return clang::format::format("-", FailOnIncompleteFormat);

  ...

  // Sequentially process each file specified on the command line
  for (const auto &FileName : FileNames) {
    // Check for .clang-format-ignore
    const bool Ignored = isIgnored(FileName);
    ...
    // If the pattern matches the pattern written in .clang-format-ignore,
    // do nothing and proceed to the next file
    if (Ignored)
      continue;
    ...
    // do formatting
    Error |= clang::format::format(FileName, FailOnIncompleteFormat);
  }

The isIgnored() function, which determines whether or not to ignore using .clang-format-ignore, is only called in the part that processes the files enumerated on the command line in order.

[kakkoko]

@owenca Thanks for the review. I applied all of the suggestions as I thought they were all appropriate.

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