llvm-project/clang/test/Preprocessor/first-line-indent.c
Michael Kruse ae6b400002 [Preprocessor] Implement -fminimize-whitespace.
This patch adds the -fminimize-whitespace with the following effects:

 * If combined with -E, remove as much non-line-breaking whitespace as
   possible.

 * If combined with -E -P, removes as much whitespace as possible,
   including line-breaks.

The motivation is to reduce the amount of insignificant changes in the
preprocessed output with source files where only whitespace has been
changed (add/remove comments, clang-format, etc.) which is in particular
useful with ccache.

A patch for ccache for using this flag has been proposed to ccache as well:
https://github.com/ccache/ccache/pull/815, which will use
-fnormalize-whitespace when clang-13 has been detected, and additionally
uses -P in "unify_mode". ccache already had a unify_mode in an older
version which was removed because of problems that using the
preprocessor itself does not have (such that the custom tokenizer did
not recognize C++11 raw strings).

This patch slightly reorganizes which part is responsible for adding
newlines that are required for semantics. It is now either
startNewLineIfNeeded() or MoveToLine() but never both; this avoids the
ShouldUpdateCurrentLine workaround and avoids redundant lines being
inserted in some cases. It also fixes a mandatory newline not inserted
after a _Pragma("...") that is expanded into a #pragma.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D104601
2021-07-25 23:30:57 -05:00

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C

foo
// RUN: %clang_cc1 -E %s | FileCheck -strict-whitespace %s
// RUN: %clang_cc1 -E -fminimize-whitespace %s | FileCheck -strict-whitespace %s --check-prefix=MINCOL
// RUN: %clang_cc1 -E -fminimize-whitespace -P %s | FileCheck -strict-whitespace %s --check-prefix=MINWS
bar
// CHECK: {{^ }}foo
// CHECK: {{^ }}bar
// MINCOL: {{^}}foo
// MINCOL: {{^}}bar
// MINWS: {{^}}foo bar