[clang-format] Respect ColumnLimit 0 line breaks in inline asm

[rymiel]

Summary

Previously, using ColumnLimit: 0 with extended inline asm with the
BreakBeforeInlineASMColon: OnlyMultiline option (the default style),
the formatter would act as if in Always mode, meaning a line break was
added before every colon in an extended inline assembly block.

This patch respects the already existing line breaks, and doesn't add
any new ones, if in ColumnLimit 0 mode.

Behaviour with Always stays as expected, with a break before every colon
regardless of any existing line breaks.

Behaviour with Never was broken before, and remains broken with this patch,
it is just never respected in ColumnLimit 0 mode.

Fixes https://github.com/llvm/llvm-project/issues/62754

[owenpan]

clang/lib/Format/ContinuationIndenter.cpp

361

FWIW.

clang/unittests/Format/FormatTest.cpp

4617–4650

FWIW, it's easier to read IMO.

[rymiel]

Apply suggestions from review

[owenpan]

clang/unittests/Format/FormatTest.cpp

4626–4627

We have verifyNoChange now. See D153109.

4630–4632

[rymiel]

clang/unittests/Format/FormatTest.cpp

4626–4627

Sorry, this patch was so old and I forgot that refactor happened, thanks for reminding me, i pushed https://github.com/llvm/llvm-project/commit/6e39b0ddf08ab5cd44fed2d16e9669d64aa733ef

clang/lib/Format/ContinuationIndenter.cpp

bool ContinuationIndenter::mustBreak(const LineState &State) {
   if (Style.BraceWrapping.BeforeLambdaBody && Current.CanBreakBefore &&
       Current.is(TT_LambdaLBrace) && Previous.isNot(TT_LineComment)) {
     auto LambdaBodyLength = getLengthToMatchingParen(Current, State.Stack);
     return LambdaBodyLength > getColumnLimit(State);
   }
   if (Current.MustBreakBefore ||
       (Current.is(TT_InlineASMColon) &&
        (Style.BreakBeforeInlineASMColon == FormatStyle::BBIAS_Always ||
-        Style.BreakBeforeInlineASMColon == FormatStyle::BBIAS_OnlyMultiline))) {
+        (Style.BreakBeforeInlineASMColon == FormatStyle::BBIAS_OnlyMultiline &&
+         Style.ColumnLimit > 0)))) {
     return true;
   }
   if (CurrentState.BreakBeforeClosingBrace &&
       Current.closesBlockOrBlockTypeList(Style)) {
     return true;
   }
   if (CurrentState.BreakBeforeClosingParen && Current.is(tok::r_paren))
     return true;

clang/unittests/Format/FormatTest.cpp

verifyFormat("void function() {\n"
                "  asm(\"\");\n"
                "}");
   EXPECT_EQ("__asm {\n"
             "}\n"
             "int i;",
             format("__asm   {\n"
                    "}\n"
                    "int   i;"));
+
+  auto Style = getLLVMStyleWithColumns(0);
+  const StringRef Code1{"asm(\"xyz\" : \"=a\"(a), \"=d\"(b) : \"a\"(data));"};
+  const StringRef Code2{"asm(\"xyz\"\n"
+                        "    : \"=a\"(a), \"=d\"(b)\n"
+                        "    : \"a\"(data));"};
+  const StringRef Code3{"asm(\"xyz\" : \"=a\"(a), \"=d\"(b)\n"
+                        "    : \"a\"(data));"};
+
+  Style.BreakBeforeInlineASMColon = FormatStyle::BBIAS_OnlyMultiline;
+  verifyFormat(Code1, Style);
+  EXPECT_EQ(Code2, format(Code2, Style));
+  EXPECT_EQ(Code3, format(Code3, Style));
+
+  Style.BreakBeforeInlineASMColon = FormatStyle::BBIAS_Always;
+  EXPECT_EQ(Code2, format(Code1, Style));
+  EXPECT_EQ(Code2, format(Code2, Style));
+  EXPECT_EQ(Code2, format(Code3, Style));
 }
 
 TEST_F(FormatTest, FormatTryCatch) {
   verifyFormat("try {\n"
                "  throw a * b;\n"
                "} catch (int a) {\n"
                "  // Do nothing.\n"
                "} catch (...) {\n"
                "  exit(42);\n"
                "}");
 
   // Function-level try statements.
   verifyFormat("int f() try { return 4; } catch (...) {\n"
                "  return 5;\n"
                "}");
   verifyFormat("class A {\n"
                "  int a;\n"
                "  A() try : a(0) {\n"
                "  } catch (...) {\n"
                "    throw;\n"
                "  }\n"
                "};\n");
   verifyFormat("class A {\n"
                "  int a;\n"
                "  A() try : a(0), b{1} {\n"
                "  } catch (...) {\n"