[lldb] print a notice when `source list` paging reaches the end of th… #137515

hapeeeeee · 2025-04-27T13:45:31Z

This PR fixes the issue where the list command does not output a prompt when reaching the end of the file.
Closes #128507.

github-actions · 2025-04-27T13:45:50Z

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llvmbot · 2025-04-27T13:46:24Z

@llvm/pr-subscribers-lldb

Author: None (hapeeeeee)

Changes

This PR fixes the issue where the list command does not output a prompt when reaching the end of the file.
Closes #128507.

Full diff: https://github.com/llvm/llvm-project/pull/137515.diff

2 Files Affected:

(modified) lldb/source/Core/SourceManager.cpp (+5-2)
(added) lldb/test/Shell/Commands/command-list-reach-end-of-file.test (+16)

diff --git a/lldb/source/Core/SourceManager.cpp b/lldb/source/Core/SourceManager.cpp
index d63d42de14e80..b57d8b3e20316 100644
--- a/lldb/source/Core/SourceManager.cpp
+++ b/lldb/source/Core/SourceManager.cpp
@@ -360,8 +360,11 @@ size_t SourceManager::DisplayMoreWithLineNumbers(
     GetDefaultFileAndLine();
 
   if (last_file_sp) {
-    if (m_last_line == UINT32_MAX)
-      return 0;
+    if (m_last_line == UINT32_MAX) {
+      Stream::ByteDelta delta(*s);
+      s->Printf("note: reached the end of current file, no more to page\n");
+      return *delta;
+    }
 
     if (reverse && m_last_line == 1)
       return 0;
diff --git a/lldb/test/Shell/Commands/command-list-reach-end-of-file.test b/lldb/test/Shell/Commands/command-list-reach-end-of-file.test
new file mode 100644
index 0000000000000..61237ce4af542
--- /dev/null
+++ b/lldb/test/Shell/Commands/command-list-reach-end-of-file.test
@@ -0,0 +1,16 @@
+# RUN: %clang_host -g -O0 %S/Inputs/sigchld.c -o %t.out
+# RUN: %lldb %t.out -b -s %s | FileCheck %s
+
+b main
+r
+list
+# CHECK: assert (child_pid != -1);
+
+list
+# CHECK: printf("signo = %d\n", SIGCHLD);
+
+list 
+# CHECK: return 0;
+
+list 
+# CHECK: note: reached the end of current file, no more to page

jimingham · 2025-04-28T21:21:14Z

It seems wrong to have the source manager pretend there are more lines in the file with the content "there are no more lines in this file". At some point, someone is going to want to know that there are no more lines and this artificial content will be confusing.

It would be better to have the source manager return some kind of error and have the printer cons up the user-facing message.

hapeeeeee · 2025-04-29T03:00:43Z

It seems wrong to have the source manager pretend there are more lines in the file with the content "there are no more lines in this file". At some point, someone is going to want to know that there are no more lines and this artificial content will be confusing.

It would be better to have the source manager return some kind of error and have the printer cons up the user-facing message.

I believe you are correct. I have updated the code so that the prompt output is now returned by SourceManager, and I have differentiated the causes. Could you please review my commit again? @jimingham

jimingham

That's better, but checking something the SourceManager calls the last line against UINT32_MAX seem to me too much implementation detail. I also can't see any other reason why m_last_line would be useful outside the SourceManager.

So maybe a better API would be

bool SourceManager::AtLastLine() { return m_last_line == UINT32_MAX; }

Then client code doesn't have to know how the SourceManager manages its paging through the source file.

Also, it would be good in your test to page twice past the end of the source buffer, not just once. That SHOULD just present the same error again, but it would be good to assert that it does.

hapeeeeee · 2025-04-30T01:43:01Z

That's better, but checking something the SourceManager calls the last line against UINT32_MAX seem to me too much implementation detail. I also can't see any other reason why m_last_line would be useful outside the SourceManager.

So maybe a better API would be

bool SourceManager::AtLastLine() { return m_last_line == UINT32_MAX; }

Then client code doesn't have to know how the SourceManager manages its paging through the source file.

As you suggested, I’ve encapsulated the AsLastLine for checking whether a line is the last one, and reused this API in the SourceManager to replace the original logic for determining the last line.

Also, it would be good in your test to page twice past the end of the source buffer, not just once. That SHOULD just present the same error again, but it would be good to assert that it does.

I added a second list command when reaching the end of the file to ensure the output is consistent across both attempts.

Could you please review my commit again? @jimingham

jimingham · 2025-04-30T16:37:31Z

lldb/source/Commands/CommandObjectSource.cpp

@@ -1067,7 +1067,14 @@ class CommandObjectSourceList : public CommandObjectParsed {
                &result.GetOutputStream(), m_options.num_lines,
                m_options.reverse, GetBreakpointLocations())) {
          result.SetStatus(eReturnStatusSuccessFinishResult);
+        } else {
+          if (target.GetSourceManager().AsLastLine(m_options.reverse)) {


If you go in reverse and try to page past the beginning of the file we really shouldn't print "Reached the end to the file". Maybe:

result.AppendNoteWithFormat("Reached {0} of the file, no more to page", m_options.reverse ? "beginning" : "end");

If you go in reverse and try to page past the beginning of the file we really shouldn't print "Reached the end to the file". Maybe:如果您反向操作并尝试翻页超过文件开头，我们真的不应该打印 "已到达文件末尾"。或许：

result.AppendNoteWithFormat("Reached {0} of the file, no more to page", m_options.reverse ? "beginning" : "end");result.AppendNoteWithFormat("已到达文件的第{0}处，没有更多可翻页", m_options.reverse ? "开始" : "结束");

I have already added different prompt messages based on reverse printing.

jimingham · 2025-04-30T16:39:02Z

lldb/test/Shell/Commands/command-list-reach-end-of-file.test

+list 
+# CHECK: note: Reached end of the file, no more to page
+
+list 


That's good. There should also be a test for scrolling past the beginning of the file in reverse, since you added a good behavior for that.

I added a test file command-list-reach-beginning-of-file.test for when the beginning of the file is reached, and ran the test twice, getting expected result both times.

jimingham

LGTM

JDevlieghere · 2025-05-01T19:46:28Z

lldb/include/lldb/Core/SourceManager.h

@@ -155,6 +155,9 @@ class SourceManager {
  ~SourceManager();

  FileSP GetLastFile() { return GetFile(m_last_support_file_sp); }
+  bool AsLastLine(bool reverse) {


Is this a typo?

Suggested change

bool AsLastLine(bool reverse) {

bool AtLastLine(bool reverse) {

Is this a typo?

Yes, it is a mistake. I have fixed it. Could you please review my commit again? @JDevlieghere

…e file

hapeeeeee · 2025-05-07T09:24:59Z

Hi @JDevlieghere , I've corrected the typos. Could you please review my changes again?

hapeeeeee · 2025-05-08T13:17:12Z

Hi @JDevlieghere @jinmingjian , all required checks have passed and the PR has received approvals. Would you mind helping merge this PR? Thanks!

github-actions · 2025-05-08T14:01:35Z

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Added in #137515, as the source uses unistd.h which isn't present there. | C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\llvm-project\lldb\test\Shell\Commands/Inputs/sigchld.c:4:10: fatal error: 'unistd.h' file not found | 4 | #include <unistd.h> | | ^~~~~~~~~~ | 1 error generated.

DavidSpickett · 2025-05-09T10:32:51Z

I've skipped the new tests on Windows because we don't have the headers the sigchld example uses.

(no notification of the failure was sent because we were already failing some lldb-dap tests)

Added in llvm/llvm-project#137515, as the source uses unistd.h which isn't present there. | C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\llvm-project\lldb\test\Shell\Commands/Inputs/sigchld.c:4:10: fatal error: 'unistd.h' file not found | 4 | #include <unistd.h> | | ^~~~~~~~~~ | 1 error generated.

hapeeeeee · 2025-05-09T13:24:24Z

I've skipped the new tests on Windows because we don't have the headers the sigchld example uses.我跳过了 Windows 上的新测试，因为我们没有 sigchld 示例使用的头文件。

(no notification of the failure was sent because we were already failing some lldb-dap tests)（没有发送失败通知，因为我们已经有一些 lldb-dap 测试失败了）

The new tests are only applied to the command line, and they should be cross-platform. Maybe I should choose a more general source code for testing?

DavidSpickett · 2025-05-09T13:43:48Z

That would be great if you can, there isn't one in that folder right now but you can find another elsewhere, or add a new file. I didn't want to go changing all the check lines myself in case I broke something.

hapeeeeee · 2025-05-09T13:46:25Z

That would be great if you can, there isn't one in that folder right now but you can find another elsewhere, or add a new file. I didn't want to go changing all the check lines myself in case I broke something.如果你能做到那就太好了，那个文件夹里现在没有，但你可以在别处找到另一个，或者添加一个新文件。我不想自己去改所有的检查行，以免破坏了什么。

If I modified the test file, should I create a new PR to fix it?

DavidSpickett · 2025-05-09T13:49:35Z

Yes please.

hapeeeeee requested a review from JDevlieghere as a code owner April 27, 2025 13:45

llvmbot added the lldb label Apr 27, 2025

hapeeeeee force-pushed the issue-list-no-source branch from 2d66140 to cc39f34 Compare April 29, 2025 02:53

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hapeeeeee requested a review from jimingham April 29, 2025 23:58

hapeeeeee force-pushed the issue-list-no-source branch from cc39f34 to edd562c Compare April 30, 2025 01:36

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hapeeeeee force-pushed the issue-list-no-source branch from edd562c to 3c0bd90 Compare May 1, 2025 01:16

hapeeeeee requested a review from jimingham May 1, 2025 01:30

jimingham approved these changes May 1, 2025

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JDevlieghere reviewed May 1, 2025

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[lldb] print a notice when source list paging reaches the end of th…

0d44818

…e file

hapeeeeee force-pushed the issue-list-no-source branch from 3c0bd90 to 0d44818 Compare May 2, 2025 00:51

JDevlieghere approved these changes May 7, 2025

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JDevlieghere merged commit b5674cb into llvm:main May 8, 2025
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hapeeeeee mentioned this pull request May 9, 2025

[lldb][test] Fix beginning/end of file test failed on Windows #139278

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	bool AsLastLine(bool reverse) {
	bool AtLastLine(bool reverse) {

[lldb] print a notice when source list paging reaches the end of th… #137515

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