[clang] [clang] Add source range to 'use of undeclared identifier' diagnostics (PR #117671)

[Timm Baeder via cfe-commits]

Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/117671 at github.com>


tbaederr wrote:

It's the same problem again.

For this code:
```c++

#define F(x) x + 1
#define G(x) F(x) + 2
#define ADD(x,y) G(x) + y
#define LEVEL4(x) ADD(p,x)
#define LEVEL3(x) LEVEL4(x)
#define LEVEL2(x) LEVEL3(x)
#define LEVEL1(x) LEVEL2(x)

int a = LEVEL1(b);
```

The previous output was:
```
./array.cpp:34:9: error: use of undeclared identifier 'p'
   34 | int a = LEVEL1(b);
      |         ^
./array.cpp:32:19: note: expanded from macro 'LEVEL1'
   32 | #define LEVEL1(x) LEVEL2(x)
      |                   ^
./array.cpp:31:19: note: expanded from macro 'LEVEL2'
   31 | #define LEVEL2(x) LEVEL3(x)
      |                   ^
./array.cpp:30:19: note: expanded from macro 'LEVEL3'
   30 | #define LEVEL3(x) LEVEL4(x)
      |                   ^
./array.cpp:29:23: note: expanded from macro 'LEVEL4'
   29 | #define LEVEL4(x) ADD(p,x)
      |                       ^
./array.cpp:34:16: error: use of undeclared identifier 'b'
   34 | int a = LEVEL1(b);
      |                ^
2 errors generated.
```

and we now print:
```
./array.cpp:34:9: error: use of undeclared identifier 'p'
   34 | int a = LEVEL1(b);
      |         ^~~~~~~~~
./array.cpp:32:19: note: expanded from macro 'LEVEL1'
   32 | #define LEVEL1(x) LEVEL2(x)
      |                   ^~~~~~~~~
./array.cpp:31:19: note: expanded from macro 'LEVEL2'
   31 | #define LEVEL2(x) LEVEL3(x)
      |                   ^~~~~~~~~
./array.cpp:30:19: note: expanded from macro 'LEVEL3'
   30 | #define LEVEL3(x) LEVEL4(x)
      |                   ^~~~~~~~~
note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
./array.cpp:28:20: note: expanded from macro 'ADD'
   28 | #define ADD(x,y) G(x) + y
      |                    ^
./array.cpp:27:16: note: expanded from macro 'G'
   27 | #define G(x) F(x) + 2
      |                ^
./array.cpp:26:14: note: expanded from macro 'F'
   26 | #define F(x) x + 1
      |              ^
./array.cpp:34:16: error: use of undeclared identifier 'b'
   34 | int a = LEVEL1(b);
      |                ^
./array.cpp:32:26: note: expanded from macro 'LEVEL1'
   32 | #define LEVEL1(x) LEVEL2(x)
      |                          ^
./array.cpp:31:26: note: expanded from macro 'LEVEL2'
   31 | #define LEVEL2(x) LEVEL3(x)
      |                          ^
./array.cpp:30:26: note: expanded from macro 'LEVEL3'
   30 | #define LEVEL3(x) LEVEL4(x)
      |                          ^
./array.cpp:29:25: note: expanded from macro 'LEVEL4'
   29 | #define LEVEL4(x) ADD(p,x)
      |                         ^
./array.cpp:28:25: note: expanded from macro 'ADD'
   28 | #define ADD(x,y) G(x) + y
      |                         ^
2 errors generated.
```

but this is not a bug introduced by the changes, rather, the newly supplied (valid!) source ranges now get taken into account in `checkRangesForMacroArgExpansion()` in `Frontend/DiagnosticRenderer.cpp`.



https://github.com/llvm/llvm-project/pull/117671