[clang-format] Handle generic selections inside parentheses

[sstwcw]

new

while (_Generic(x, //
           long: x)(x) > x) {
}
while (_Generic(x, //
           long: x)(x)) {
}

old

while (_Generic(x, //
       long: x)(x) > x) {
}
while (_Generic(x, //
    long: x)(x)) {
}

In the first case above, the second line previously aligned to the open parenthesis. The 4 spaces did not get added by the fallback line near the end of getNewLineColumn because there was already some indentaton. Now the spaces get added explicitly.

In the second case above, without the fake parentheses, the second line did not respect the outer parentheses. Because the LastSpace field did not get set without the fake parentheses. Now the indentation of the outer level is used instead.

[llvmbot]

@llvm/pr-subscribers-clang-format

Author: None (sstwcw)

Changes

new

while (_Generic(x, //
           long: x)(x) > x) {
}
while (_Generic(x, //
           long: x)(x)) {
}

old

while (_Generic(x, //
       long: x)(x) > x) {
}
while (_Generic(x, //
    long: x)(x)) {
}

In the first case above, the second line previously aligned to the open parenthesis. The 4 spaces did not get added by the fallback line near the end of getNewLineColumn because there was already some indentaton. Now the spaces get added explicitly.

In the second case above, without the fake parentheses, the second line did not respect the outer parentheses. Because the LastSpace field did not get set without the fake parentheses. Now the indentation of the outer level is used instead.

---

Full diff: https://github.com/llvm/llvm-project/pull/79785.diff

2 Files Affected:

• (modified) clang/lib/Format/ContinuationIndenter.cpp (+5-2)
• (modified) clang/unittests/Format/FormatTest.cpp (+9)

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index a3eb9138b21833..a1c5a297c67c13 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1694,8 +1694,11 @@ void ContinuationIndenter::moveStatePastFakeLParens(LineState &State,
     // Special case for generic selection expressions, its comma-separated
     // expressions are not aligned to the opening paren like regular calls, but
     // rather continuation-indented relative to the _Generic keyword.
-    if (Previous && Previous->endsSequence(tok::l_paren, tok::kw__Generic))
-      NewParenState.Indent = CurrentState.LastSpace;
+    if (Previous && Previous->endsSequence(tok::l_paren, tok::kw__Generic) &&
+        State.Stack.size() >= 2) {
+      NewParenState.Indent =
+          State.Stack.end()[-2].Indent + Style.ContinuationIndentWidth;
+    }
 
     if ((shouldUnindentNextOperator(Current) ||
          (Previous &&
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index e5e763edf5b5bf..c066107bebdd73 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -24111,6 +24111,15 @@ TEST_F(FormatTest, C11Generic) {
                "    double _Complex: dc,\n"
                "    long double _Complex: ldc)");
 
+  verifyFormat("while (_Generic(x, //\n"
+               "           long: x)(x) > x) {\n"
+               "}");
+  verifyFormat("while (_Generic(x, //\n"
+               "           long: x)(x)) {\n"
+               "}");
+  verifyFormat("x(_Generic(x, //\n"
+               "      long: x)(x));");
+
   FormatStyle Style = getLLVMStyle();
   Style.ColumnLimit = 40;
   verifyFormat("#define LIMIT_MAX(T)                   \\\n"

[HazardyKnusperkeks]

This is freaky, never thought I'd ever see operator[] on iterators used, and in such a way.

[owenca]

To be consistent with the other dozen similar sinppets:

Suggested change

	State.Stack.size() >= 2) {
	NewParenState.Indent =
	State.Stack.end()[-2].Indent + Style.ContinuationIndentWidth;
	State.Stack.size() > 1) {
	NewParenState.Indent =
	State.Stack[State.Stack.size() - 2].Indent + Style.ContinuationIndentWidth;