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377748fd7b
Summary:
clang has `-Wextra-semi` (D43162), which is not dictated by the currently selected standard.
While that is great, there is at least one more source of need-less semis - 'null statements'.
Sometimes, they are needed:
```
for(int x = 0; continueToDoWork(x); x++)
; // Ugly code, but the semi is needed here.
```
But sometimes they are just there for no reason:
```
switch(X) {
case 0:
return -2345;
case 5:
return 0;
default:
return 42;
}; // <- oops
;;;;;;;;;;; <- OOOOPS, still not diagnosed. Clearly this is junk.
```
Additionally:
```
if(; // <- empty init-statement
true)
;
switch (; // empty init-statement
x) {
...
}
for (; // <- empty init-statement
int y : S())
;
}
As usual, things may or may not go sideways in the presence of macros.
While evaluating this diag on my codebase of interest, it was unsurprisingly
discovered that Google Test macros are *very* prone to this.
And it seems many issues are deep within the GTest itself, not
in the snippets passed from the codebase that uses GTest.
So after some thought, i decided not do issue a diagnostic if the semi
is within *any* macro, be it either from the normal header, or system header.
Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=39111 | PR39111 ]]
Reviewers: rsmith, aaron.ballman, efriedma
Reviewed By: aaron.ballman
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D52695
llvm-svn: 347339
97 lines
2.0 KiB
C++
97 lines
2.0 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -Wextra-semi-stmt -verify %s
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// RUN: cp %s %t
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// RUN: %clang_cc1 -x c++ -Wextra-semi-stmt -fixit %t
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// RUN: %clang_cc1 -x c++ -Wextra-semi-stmt -Werror %t
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#define GOODMACRO(varname) int varname
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#define BETTERMACRO(varname) GOODMACRO(varname);
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#define NULLMACRO(varname)
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enum MyEnum {
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E1,
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E2
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};
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void test() {
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; // expected-warning {{empty expression statement has no effect; remove unnecessary ';' to silence this warning}}
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;
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// This removal of extra semi also consumes all the comments.
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// clang-format: off
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;;;
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// clang-format: on
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// clang-format: off
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;NULLMACRO(ZZ);
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// clang-format: on
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{}; // expected-warning {{empty expression statement has no effect; remove unnecessary ';' to silence this warning}}
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{
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; // expected-warning {{empty expression statement has no effect; remove unnecessary ';' to silence this warning}}
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}
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if (true) {
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; // expected-warning {{empty expression statement has no effect; remove unnecessary ';' to silence this warning}}
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}
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GOODMACRO(v0); // OK
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GOODMACRO(v1;) // OK
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BETTERMACRO(v2) // OK
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BETTERMACRO(v3;) // Extra ';', but within macro expansion, so ignored.
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BETTERMACRO(v4); // expected-warning {{empty expression statement has no effect; remove unnecessary ';' to silence this warning}}
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BETTERMACRO(v5;); // expected-warning {{empty expression statement has no effect; remove unnecessary ';' to silence this warning}}
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NULLMACRO(v6) // OK
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NULLMACRO(v7); // OK. This could be either GOODMACRO() or BETTERMACRO() situation, so we can't know we can drop it.
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if (true)
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; // OK
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while (true)
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; // OK
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do
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; // OK
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while (true);
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for (;;) // OK
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; // OK
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MyEnum my_enum;
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switch (my_enum) {
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case E1:
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// stuff
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break;
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case E2:; // OK
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}
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for (;;) {
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for (;;) {
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goto contin_outer;
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}
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contin_outer:; // OK
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}
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}
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;
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namespace NS {};
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void foo(int x) {
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switch (x) {
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case 0:
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[[fallthrough]];
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case 1:
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return;
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}
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}
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[[]];
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