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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
65 lines
1.2 KiB
C++
65 lines
1.2 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -Wextra -std=c++2a -verify %s
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// RUN: %clang_cc1 -fsyntax-only -Wextra-semi-stmt -std=c++2a -verify %s
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// RUN: %clang_cc1 -fsyntax-only -Wempty-init-stmt -std=c++2a -verify %s
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// RUN: cp %s %t
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// RUN: %clang_cc1 -x c++ -Wempty-init-stmt -std=c++2a -fixit %t
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// RUN: %clang_cc1 -x c++ -Wempty-init-stmt -std=c++2a -Werror %t
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struct S {
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int *begin();
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int *end();
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};
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void naive(int x) {
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if (; true) // expected-warning {{empty initialization statement of 'if' has no effect}}
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;
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switch (; x) { // expected-warning {{empty initialization statement of 'switch' has no effect}}
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}
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for (; int y : S()) // expected-warning {{empty initialization statement of 'range-based for' has no effect}}
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;
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for (;;) // OK
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;
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}
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#define NULLMACRO
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void with_null_macro(int x) {
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if (NULLMACRO; true)
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;
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switch (NULLMACRO; x) {
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}
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for (NULLMACRO; int y : S())
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;
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}
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#define SEMIMACRO ;
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void with_semi_macro(int x) {
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if (SEMIMACRO true)
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;
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switch (SEMIMACRO x) {
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}
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for (SEMIMACRO int y : S())
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;
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}
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#define PASSTHROUGHMACRO(x) x
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void with_passthrough_macro(int x) {
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if (PASSTHROUGHMACRO(;) true)
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;
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switch (PASSTHROUGHMACRO(;) x) {
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}
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for (PASSTHROUGHMACRO(;) int y : S())
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;
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}
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