[lldb] Fix a crash when two diagnostics are on the same column or in …

[adrian-prantl]

…reverse order

The second inner loop (only) was missing the check for offset > column. Also this patch sorts the diagnostics before printing them.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Adrian Prantl (adrian-prantl)

Changes

…reverse order

The second inner loop (only) was missing the check for offset > column. Also this patch sorts the diagnostics before printing them.

---

Full diff: https://github.com/llvm/llvm-project/pull/112451.diff

2 Files Affected:

• (modified) lldb/source/Utility/DiagnosticsRendering.cpp (+25-7)
• (modified) lldb/unittests/Utility/DiagnosticsRenderingTest.cpp (+26-2)

diff --git a/lldb/source/Utility/DiagnosticsRendering.cpp b/lldb/source/Utility/DiagnosticsRendering.cpp
index 96caf934cc2315..dd8f5dd1700c26 100644
--- a/lldb/source/Utility/DiagnosticsRendering.cpp
+++ b/lldb/source/Utility/DiagnosticsRendering.cpp
@@ -77,11 +77,7 @@ void RenderDiagnosticDetails(Stream &stream,
     spacer = "";
   }
 
-  // Print a line with caret indicator(s) below the lldb prompt + command.
-  const size_t padding = *offset_in_command;
-  stream << std::string(padding, ' ');
-
-  size_t offset = 1;
+  // Partition the diagnostics.
   std::vector<DiagnosticDetail> remaining_details, other_details,
       hidden_details;
   for (const DiagnosticDetail &detail : details) {
@@ -98,10 +94,31 @@ void RenderDiagnosticDetails(Stream &stream,
       continue;
     }
 
-    auto &loc = *detail.source_location;
     remaining_details.push_back(detail);
+  }
+
+  // Sort the diagnostics.
+  auto sort = [](auto &ds) {
+    std::sort(ds.begin(), ds.end(), [](auto &d1, auto &d2) {
+      auto l1 = d1.source_location.value_or(DiagnosticDetail::SourceLocation{});
+      auto l2 = d2.source_location.value_or(DiagnosticDetail::SourceLocation{});
+      return std::pair(l1.line, l2.column) < std::pair(l1.line, l2.column);
+    });
+  };
+  sort(remaining_details);
+  sort(other_details);
+  sort(hidden_details);
+
+  // Print a line with caret indicator(s) below the lldb prompt + command.
+  const size_t padding = *offset_in_command;
+  stream << std::string(padding, ' ');
+  size_t offset = 1;
+  for (const DiagnosticDetail &detail : remaining_details) {
+    auto &loc = *detail.source_location;
+
     if (offset > loc.column)
       continue;
+
     stream << std::string(loc.column - offset, ' ') << cursor;
     for (unsigned i = 0; i + 1 < loc.length; ++i)
       stream << underline;
@@ -121,7 +138,8 @@ void RenderDiagnosticDetails(Stream &stream,
     for (auto &remaining_detail :
          llvm::ArrayRef(remaining_details).drop_back(1)) {
       uint16_t column = remaining_detail.source_location->column;
-      stream << std::string(column - offset, ' ') << vbar;
+      if (offset <= column)
+        stream << std::string(column - offset, ' ') << vbar;
       offset = column + 1;
     }
 
diff --git a/lldb/unittests/Utility/DiagnosticsRenderingTest.cpp b/lldb/unittests/Utility/DiagnosticsRenderingTest.cpp
index 2bd80796b8074c..e55b23368f0ea2 100644
--- a/lldb/unittests/Utility/DiagnosticsRenderingTest.cpp
+++ b/lldb/unittests/Utility/DiagnosticsRenderingTest.cpp
@@ -16,12 +16,36 @@ std::string Render(std::vector<DiagnosticDetail> details) {
 } // namespace
 
 TEST_F(ErrorDisplayTest, RenderStatus) {
-  DiagnosticDetail::SourceLocation inline_loc;
-  inline_loc.in_user_input = true;
   {
+    DiagnosticDetail::SourceLocation inline_loc;
+    inline_loc.in_user_input = true;
     std::string result =
         Render({DiagnosticDetail{inline_loc, eSeverityError, "foo", ""}});
     ASSERT_TRUE(StringRef(result).contains("error:"));
     ASSERT_TRUE(StringRef(result).contains("foo"));
   }
+
+  {
+    DiagnosticDetail::SourceLocation loc1 = {FileSpec{"a.c"}, 13,  11, 0,
+                                             false,           true};
+    DiagnosticDetail::SourceLocation loc2 = {FileSpec{"a.c"}, 13,  13, 0,
+                                             false,           true};
+    std::string result =
+        Render({DiagnosticDetail{loc1, eSeverityError, "1", "1"},
+                DiagnosticDetail{loc1, eSeverityError, "2", "3"},
+                DiagnosticDetail{loc2, eSeverityError, "3", "3"}});
+    ASSERT_TRUE(StringRef(result).contains("error: 1"));
+    ASSERT_TRUE(StringRef(result).contains("error: 3"));
+    ASSERT_TRUE(StringRef(result).contains("error: 2"));
+  }
+  {
+    DiagnosticDetail::SourceLocation loc1 = {FileSpec{"a.c"}, 1,   20, 0,
+                                             false,           true};
+    DiagnosticDetail::SourceLocation loc2 = {FileSpec{"a.c"}, 2,   10, 0,
+                                             false,           true};
+    std::string result =
+        Render({DiagnosticDetail{loc2, eSeverityError, "X", "X"},
+                DiagnosticDetail{loc1, eSeverityError, "Y", "Y"}});
+    ASSERT_LT(StringRef(result).find("Y"), StringRef(result).find("X"));
+  }
 }

[JDevlieghere]

Thanks!

[slackito]

This comparison is always false, both sides of the < operator are identical.

[slackito]

Btw, I found that bug because this commit is causing flakiness in the test. So the bad comparison is producing the expected results, sometimes.

Some more data I gathered poking around to hopefully help debug. If I change the comparator to

  return std::pair(l1.line, l1.column) < std::pair(l2.line, l2.column)

I still get (non-flaky) test failures. I think at least one of these test cases is wrong:

  {
    // Test that diagnostics in reverse order are emitted correctly.
    SourceLocation loc1 = {FileSpec{"a.c"}, 1, 20, 0, false, true};
    SourceLocation loc2 = {FileSpec{"a.c"}, 2, 10, 0, false, true};
    std::string result =
        Render({DiagnosticDetail{loc2, eSeverityError, "X", "X"},
                DiagnosticDetail{loc1, eSeverityError, "Y", "Y"}});
    ASSERT_LT(StringRef(result).find("Y"), StringRef(result).find("X"));
  }
  {
    // Test that diagnostics in reverse order are emitted correctly.
    SourceLocation loc1 = {FileSpec{"a.c"}, 2, 10, 0, false, true};
    SourceLocation loc2 = {FileSpec{"a.c"}, 1, 20, 0, false, true};
    std::string result =
        Render({DiagnosticDetail{loc2, eSeverityError, "X", "X"},
                DiagnosticDetail{loc1, eSeverityError, "Y", "Y"}});
    ASSERT_LT(StringRef(result).find("Y"), StringRef(result).find("X"));
  }

In the first one, we have "X" in loc2 (line 2, col 10), and "Y" in loc1 (line 1, col 20), so they are in reverse order.
In the second one, we have "X" in loc2 (line 1, col 20), and "Y" in loc1 (line 2, col 10), so despite the comment they are not in reverse order if lines are supposed to be compared first.

[adrian-prantl]

Thanks!

[adrian-prantl]

#113220