[clang-scan-deps] [P1689] Inconsistent path style for make style dependency output

[ChuanqiXu9]

Reproducer:

// a.h
// empty 

// a.cpp
#include "a.h"
#include <stdarg.h>

Use the following command to get the make style dependency information:

clang-scan-deps -format=p1689  -- <abs-path>/clang++  -std=c++20 a.cpp -c -o a.o -MD -MT a.ddi -MF a.dep
cat a.dep

we get:

a.ddi: \
  <absolute-path>/a.cpp \
  <absolute-path>/a.h \
  <absolute-path>/stdarg.h \
  <absolute-path>/__stdarg___gnuc_va_list.h \
  <absolute-path>/__stdarg_va_list.h \
  <absolute-path>/__stdarg_va_arg.h \
  <absolute-path>/__stdarg___va_copy.h \
  <absolute-path>/__stdarg_va_copy.h

But if we try to get the information by the compiler itself:

a.ddi: a.cpp a.h \
  <absolute-path>/stdarg.h \
  <absolute-path>/__stdarg___gnuc_va_list.h \
  <absolute-path>/__stdarg_va_list.h \
  <absolute-path>/__stdarg_va_arg.h \
  <absolute-path>/__stdarg___va_copy.h \
  <absolute-path>/__stdarg_va_copy.h

then we can find that the path to a.cpp and a.h is not consistency. This is problematic in cases like sandboxes.