[flang-commits] [flang] [llvm] [flang] [flang-rt] Implement AT edit descriptor for Fortran 202X with appropriate handling and tests (PR #189157)

[Eugene Epshteyn via flang-commits]

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@@ -1018,3 +1018,66 @@ TEST(IOApiTests, ConfusingMinimization) {
   EXPECT_TRUE(CompareFormattedStrings(" 65504. ", got))
       << "expected ' 65504. ', got '" << got << '\''; // not 65500.!
 }
+
+// Test AT edit descriptor (F2023) - trims trailing blanks on output
+TEST(IOApiTests, ATEditDescriptorOutput) {
+  // Helper to test AT formatted output
+  auto testAT = [](const char *format, const char *input, std::size_t inputLen,
+                    const char *expect) {
+    char buffer[800];
+    auto cookie{IONAME(BeginInternalFormattedOutput)(
+        buffer, sizeof buffer, format, std::strlen(format))};
+    EXPECT_TRUE(IONAME(OutputAscii)(cookie, input, inputLen));
+    auto status{IONAME(EndIoStatement)(cookie)};
+    EXPECT_EQ(status, 0) << "AT test: '" << format << "' failed, status "
+                         << static_cast<int>(status);
+    std::string got{buffer, sizeof buffer};
+    auto lastNonBlank{got.find_last_not_of(" ")};
+    if (lastNonBlank != std::string::npos) {
+      got.resize(lastNonBlank + 1);
+    }
+    EXPECT_TRUE(CompareFormattedStrings(expect, got))
+        << "AT test: format '" << format << "' input '" << input
+        << "' expected '" << expect << "' got '" << got << "'";
+  };
+
+  // AT trims trailing blanks
+  testAT("(AT)", "hello     ", 10, "hello");
+  testAT("(AT)", "hello", 5, "hello");
+  testAT("(AT)", "  hi  ", 6, "  hi");
+  testAT("(AT)", "          ", 10, ""); // all blanks -> empty
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eugeneepshteyn wrote:

Would it be possible to avoid manually counting the length? Perhaps have `testAT` accept `const std::string&` instead of separate ptr and len.

https://github.com/llvm/llvm-project/pull/189157