clang-format: SpacesInSquareBrackets does not work properly for Java

[mikir]

The following Java snippet

public class Sample
{
    public static void createObject(Object[] arguments)
    {
        final int numElements = arguments.length;
        final Class<?>[] types = new Class<?>[numElements];
        for (int i = 0; i < numElements; ++i)
            types[i] = arguments[i].getClass();
    }
}

using the following clang-format configuration

---
Language: Java
BasedOnStyle: Microsoft
SpacesInSquareBrackets: false
...

is formatted as

public class Sample
{
    public static void createObject(Object[] arguments)
    {
        final int numElements = arguments.length;
        final Class<?>[] types = new Class<?>[ numElements ]; // wrong, spaces even if SpacesInSquareBrackets is false
        for (int i = 0; i < numElements; ++i)
            types[i] = arguments[i].getClass(); // ok, no spaces
    }
}

We are using clang-format Ubuntu clang-format version 14.0.0-1ubuntu1.1.

[mydeveloperday]

This was still an issue with 17

[llvmbot]

@llvm/issue-subscribers-bug

Author: Miki (mikir)

The following Java snippet

public class Sample
{
    public static void createObject(Object[] arguments)
    {
        final int numElements = arguments.length;
        final Class<?>[] types = new Class<?>[numElements];
        for (int i = 0; i < numElements; ++i)
            types[i] = arguments[i].getClass();
    }
}

using the following clang-format configuration

---
Language: Java
BasedOnStyle: Microsoft
SpacesInSquareBrackets: false
...

is formatted as

public class Sample
{
    public static void createObject(Object[] arguments)
    {
        final int numElements = arguments.length;
        final Class<?>[] types = new Class<?>[ numElements ]; // wrong, spaces even if SpacesInSquareBrackets is false
        for (int i = 0; i < numElements; ++i)
            types[i] = arguments[i].getClass(); // ok, no spaces
    }
}

We are using clang-format Ubuntu clang-format version 14.0.0-1ubuntu1.1.

[mydeveloperday]

small repo

public static void foo()
{
    auto types = new A[numElements];
    auto types = new Class<T>[ numElements ];
}

[mydeveloperday]

Workaround Add

SpacesInContainerLiterals: false

[mydeveloperday]

So I do think this is missing code (which is handled in C#)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 73840332e22c..86e9ed931f7c 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -4472,6 +4472,10 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Left.is(tok::r_square) && Right.is(tok::l_brace))
       return true;
+    // spaces inside square brackets.
+    if (Left.is(tok::l_square) || Right.is(tok::r_square))
+      return Style.SpacesInSquareBrackets;
+
     if (Left.is(Keywords.kw_synchronized) && Right.is(tok::l_paren)) {
       return Style.SpaceBeforeParensOptions.AfterControlStatements ||
              spaceRequiredBeforeParens(Right);
diff --git a/clang/unittests/Format/FormatTestJava.cpp b/clang/unittests/Format/FormatTestJava.cpp
index 51afe79859ec..6bb4b0013eeb 100644
--- a/clang/unittests/Format/FormatTestJava.cpp
+++ b/clang/unittests/Format/FormatTestJava.cpp
@@ -625,5 +625,20 @@ TEST_F(FormatTestJava, ShortFunctions) {
                Style);
 }

+TEST_F(FormatTestJava, ConfigurableSpacesInSquareBrackets) {
+  FormatStyle Spaces = getLLVMStyle(FormatStyle::LK_Java);
+
+  verifyFormat("Object[] arguments", Spaces);
+  verifyFormat("final Class<?>[] types = new Class<?>[numElements];", Spaces);
+  verifyFormat("types[i] = arguments[i].getClass();", Spaces);
+
+  Spaces.SpacesInSquareBrackets = true;
+
+  verifyFormat("Object[ ] arguments", Spaces);
+  verifyFormat("final Class<?>[ ] types = new Class<?>[ numElements ];",
+               Spaces);
+  verifyFormat("types[ i ] = arguments[ i ].getClass();", Spaces);
+}
+
 } // namespace format
 } // end namespace clang

[mikir]

Workaround Add

SpacesInContainerLiterals: false

Thanks a lot for your quick response and especially for this workaround. It helped.

[mydeveloperday]

A fix for this has landed in main and should form part of the 18.X release