Add option to IndentPPDirectives to respect indentation of context

[aardappel]

Bugzilla Link	36020
Version	trunk
OS	All

Extended Description

With IndentPPDirectives: AfterHash, preprocessor directives are indented, but only relative to other preprocessor directives, not to the surrounding code. So code that is intended to look like:

void foo() {
    if (bar) {
        A;
#       ifdef D
#           define E
            B;
#       endif
        C;
    }
}

is clang-formatted to:

void foo() {
    if (bar) {
        A;
#ifdef D
#    define E
        B;
#endif
        C;
    }
}

This is a follow-up from bug #17736
Related feature: llvm/llvm-bugzilla-archive#36019

[llvmbot]

+1.

There should be an option to indent preprocessor directives relative to surrounding code.

[llvmbot]

In the proposed example, not only preprocessor directives are indented.
C++ declarations are indented also:

ifdef D

define E

       B; // <- is intended to `ifdef D`

endif

Is it right?
Should preprocessor directives influent on the indentation of nested C/C++ code?

Reference C/C++ code (indent=2):

void main() { // Line intend = 0
int x = 0;
if(2) {
x += 1;
x -= 2;
}
}

Add preprocessor directives and format it with IndentPPDirectives: None:

#ifdef L0
void foo() {
#ifdef L1
int x = 0;
if (2) {
#ifdef L2
x += 1;
#ifdef L3
x -= 2;
#endif
#endif
}
#endif
}
#endif

How should look a right formatted code with AfterHash?

[aardappel]

Vladimir: yes, I'd say code inside PPDs should also be indented.

Your example would look like:

#ifdef L0
void foo() {

ifdef L1

int x = 0;
if (2) {

ifdef L2

   x += 1;

ifdef L3

     x -= 2;

endif

endif

}

endif

}
#endif

Or with the proposed BeforeHash (#36019 )

#ifdef L0
void foo() {
#ifdef L1
int x = 0;
if (2) {
#ifdef L2
x += 1;
#ifdef L3
x -= 2;
#endif
#endif
}
#endif
}
#endif

[llvmbot]

Wouter, in your example function void foo() is not indented although it declared inside #if/#endif block.
Is it right?
Should all top-level declarations have zero indentation even if they are declared inside a #if/#endif block?

file.cpp:

int counter = 0;

#ifdef L0
std::string top;

void foo() {
top = "";
}
#endif

or

file.cpp:

int counter = 0;

#ifdef L0
std::string top;

void foo() {
top = "";
}
#endif

[llvmbot]

Formatted code:

file_0.cpp:

int counter = 0;
#ifdef L0
std::string top;
void foo() {
top = "";
}
#endif

file_1.cpp:

int counter = 0;
#ifdef L0
std::string top;
void foo() {
top = "";
}
#endif

[aardappel]

I'd personally be fine indenting top level items as well, but my guess is that most people would prefer starting longer top level items in column 1.

[llvmbot]

Hopefully this should also support leaving indentation of pragmas alone that annotate specific parts of code.

See ODB pragma language for example: https://www.codesynthesis.com/products/odb/doc/manual.xhtml#14

I've had to disable formatting in large sections of code to prevent it messing up these pragmas. I'd even be happy to be able to disable formatting of PP directives entirely.

[llvmbot]

Troy,
I'm sorry, I stopped at the tests stage.
The problem is deeper than PP formatting.

"A twice-format problem: the format of format isn't format."
https://reviews.llvm.org/D53482

I thought that fixing without unit-tests is meaningless.
I did research, but since then the code could already have changed, I did not check it.
If you are ready to fix this problem I can try to restore my research results and compare it with the HEAD of the clan-format repo.

[aardappel]

Related bug: llvm/llvm-bugzilla-archive#39280

[llvmbot]

mentioned in issue llvm/llvm-bugzilla-archive#39163

[aardappel]

mentioned in issue llvm/llvm-bugzilla-archive#39280