Fix bug when reflowing comments that are exactly one character longer…

… than the maximum line length.

PiperOrigin-RevId: 712521148

xls/dslx/fmt/ast_fmt_test.cc

@@ -3310,6 +3310,7 @@ fn test() {
 }
 )");
 }
+
 TEST_F(ModuleFmtTest, StructLiteralBreak) {
   DoFmt(R"(struct Foo { a: u1, b: u1 }
 
@@ -3321,5 +3322,26 @@ fn test() {
 }
 )");
 }
+
+TEST_F(ModuleFmtTest, CommentsDoNotReflow100Chars) {
+  // This is 100 characters, and should not reflow.
+  DoFmt(
+      R"(// Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labo
+struct Foo { a: u1, b: u1 }
+)");
+}
+
+TEST_F(ModuleFmtTest, CommentsReflow101Chars) {
+  // This is 101 characters, and wasn't reflowing before.
+  DoFmt(
+      R"(// Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labor
+struct Foo { a: u1, b: u1 }
+)",
+      R"(// Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut
+// labor
+struct Foo { a: u1, b: u1 }
+)");
+}
+
 }  // namespace
 }  // namespace xls::dslx

xls/dslx/fmt/pretty_print.cc

@@ -255,7 +255,9 @@ void PrettyPrintInternal(const DocArena& arena, const Doc& doc,
                         // If the next token isn't going to fit we make a
                         // carriage return and go to the next prefix insertion.
                         const std::string& next_tok = remaining_toks.front();
-                        if (virtual_outcol + next_tok.size() >
+                        // Note: we add 1 to the next_tok size because we're
+                        // going to emit a space before it.
+                        if (virtual_outcol + next_tok.size() + 1 >
                             entry.text_width()) {
                           VLOG(5) << "PrefixedReflow; adding carriage "
                                      "return in advance of: `"

xls/dslx/fmt/pretty_print_test.cc

@@ -167,6 +167,16 @@ TEST(PrettyPrintTest, PrefixedReflowAfterIndentWidth40) {
     // indented)");
 }
 
+TEST(PrettyPrintTest, PrefixedReflowOffByOne) {
+  FileTable file_table;
+  DocArena arena(file_table);
+  // Total width is 8, so it should reflow since the max width is 7.
+  DocRef ref = arena.MakePrefixedReflow("// ", "1 2 3");
+  EXPECT_EQ(PrettyPrint(arena, ref, 7),
+            R"(// 1 2
+// 3)");
+}
+
 // Demonstrates that the empty line between nested elements don't have leading
 // spaces.
 TEST(PrettyPrintTest, NestLevelWithEmptyLine) {

xls/dslx/stdlib/std.x

@@ -202,8 +202,8 @@ fn smul_test() {
 // Returns unsigned division of `n` (N bits) and `d` (M bits) as quotient (N bits) and remainder (M
 // bits).
 // If dividing by `0`, returns all `1`s for quotient and `n` for remainder.
-// Implements binary long division; should be expected to use a large number of gates and have a slow
-// critical path when using combinational codegen.
+// Implements binary long division; should be expected to use a large number of gates and have a
+// slow critical path when using combinational codegen.
 pub fn iterative_div_mod<N: u32, M: u32>(n: uN[N], d: uN[M]) -> (uN[N], uN[M]) {
     // Zero extend divisor by 1 bit.
     let divisor = d as uN[M + u32:1];

xls/dslx/tests/constexpr_attrs.x

@@ -27,8 +27,8 @@ const LOCAL = LocalStruct { a: u32:8 };
 const LOCAL_STRUCT = u32[LOCAL.a]:[u32:0, u32:1, u32:2, u32:3, ...];
 
 //const imported_struct = u32[IMPORTED.a]:[u32:8, u32:9, u32:10, u32:11, ...];
-//const imported_instance = u32[constexpr::IMPORTED_STRUCT_INSTANCE.a]:[u32:8, u32:9, u32:10, u32:11,
-//...];
+//const imported_instance = u32[constexpr::IMPORTED_STRUCT_INSTANCE.a]:[u32:8, u32:9, u32:10,
+//u32:11, ...];
 
 // TODO(rspringer): 2021/03/04 Add a test that dereferences an attribute of an attribute,
 // e.g., "u32[IMPORTED_STRUCT.a.b]:[...]".

xls/dslx/tests/tuple_indexing.x

@@ -13,8 +13,8 @@
 // limitations under the License.
 
 fn tuple_index_all_bits_set(x: (u1, u2, u3, u4)) -> u4 {
-    // Tuple index access where the index has all bits set (e.g. demonstrates the index is treated as
-    // unsigned).
+    // Tuple index access where the index has all bits set (e.g. demonstrates the index is treated
+    // as unsigned).
     x.0b11
 }