[lldb-dev] Using FileCheck in lldb inline tests

[Vedant Kumar via lldb-dev]

Hello,

I'd like to make FileCheck available within lldb inline tests, in addition to existing helpers like 'runCmd' and 'expect'.

My motivation is that several tests I'm working on can't be made as rigorous as they need to be without FileCheck-style checks. In particular, the 'matching', 'substrs', and 'patterns' arguments to runCmd/expect don't allow me to verify the ordering of checked input, to be stringent about line numbers, or to capture & reuse snippets of text from the input stream.

I'd curious to know if anyone else is interested or would be willing to review this (https://reviews.llvm.org/D50751 <https://reviews.llvm.org/D50751>).

Here's an example of an inline test which benefits from FileCheck-style checking. This test is trying to check that certain frames appear in a backtrace when stopped inside of the "sink" function. Notice that without FileCheck, it's not possible to verify the order in which frames are printed, and that dealing with line numbers would be cumbersome.

```
--- a/lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/main.cpp
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/tail_call_frames/unambiguous_sequence/main.cpp
@@ -9,16 +9,21 @@
 
 volatile int x;
 
+// CHECK: frame #0: {{.*}}sink() at main.cpp:[[@LINE+2]] [opt]
 void __attribute__((noinline)) sink() {
-  x++; //% self.expect("bt", substrs = ['main', 'func1', 'func2', 'func3', 'sink'])
+  x++; //% self.filecheck("bt", "main.cpp")
 }
 
+// CHECK-NEXT: frame #1: {{.*}}func3() {{.*}}[opt] [artificial]
 void __attribute__((noinline)) func3() { sink(); /* tail */ }
 
+// CHECK-NEXT: frame #2: {{.*}}func2() at main.cpp:[[@LINE+1]] [opt]
 void __attribute__((disable_tail_calls, noinline)) func2() { func3(); /* regular */ }
 
+// CHECK-NEXT: frame #3: {{.*}}func1() {{.*}}[opt] [artificial]
 void __attribute__((noinline)) func1() { func2(); /* tail */ }
 
+// CHECK-NEXT: frame #4: {{.*}}main at main.cpp:[[@LINE+2]] [opt]
 int __attribute__((disable_tail_calls)) main() {
   func1(); /* regular */
   return 0;
```

For reference, here's the output of the "bt" command:

```
runCmd: bt
output: * thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x000000010c6a6f64 a.out`sink() at main.cpp:14 [opt]
    frame #1: 0x000000010c6a6f70 a.out`func3() at main.cpp:15 [opt] [artificial]
    frame #2: 0x000000010c6a6f89 a.out`func2() at main.cpp:21 [opt]
    frame #3: 0x000000010c6a6f90 a.out`func1() at main.cpp:21 [opt] [artificial]
    frame #4: 0x000000010c6a6fa9 a.out`main at main.cpp:28 [opt]
```

thanks,
vedant
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