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| author | Patrick Palka <ppalka@redhat.com> | 2020-03-25 12:32:43 -0400 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2020-03-25 12:33:12 -0400 |
| commit | c7a252ba2d0a08397d8fc6d6dc7db34f90f76acb (patch) | |
| tree | 7e34c9ee867c9b4b8a85e029608cd0bd476c87f6 | |
| parent | 05c13c439903eb78f109bcab62fd9a74f03a3c9b (diff) | |
| download | gcc-c7a252ba2d0a08397d8fc6d6dc7db34f90f76acb.zip gcc-c7a252ba2d0a08397d8fc6d6dc7db34f90f76acb.tar.gz gcc-c7a252ba2d0a08397d8fc6d6dc7db34f90f76acb.tar.bz2 | |
c++: Fix invalid -Wduplicated-cond warning [PR94265]
This fixes a false-positive warning from -Wduplicate-cond in the presence of an
if-statement with a non-empty init-statement. Precisely determining whether a
non-empty init-statement has side effects seems tricky and error-prone, so this
patch takes the route of unconditionally invalidating the condition chain when
it encounters such an if-statement.
gcc/cp/ChangeLog:
PR c++/94265
* parser.c (cp_parser_selection_statement) <case RID_IF>: Invalidate the
current condition chain when the if-statement has a non-empty
init-statement.
gcc/testsuite/ChangeLog:
PR c++/94265
* g++.dg/warn/Wduplicated-cond1.C: New test.
| -rw-r--r-- | gcc/cp/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/cp/parser.c | 7 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/warn/Wduplicated-cond1.C | 16 |
4 files changed, 35 insertions, 0 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index d9f87ec..34ccb9f 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,10 @@ +2020-03-25 Patrick Palka <ppalka@redhat.com> + + PR c++/94265 + * parser.c (cp_parser_selection_statement) <case RID_IF>: Invalidate the + current condition chain when the if-statement has a non-empty + init-statement. + 2020-03-25 Iain Sandoe <iain@sandoe.co.uk> PR c++/94319 diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index cbd5510..0536365 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -11934,6 +11934,13 @@ cp_parser_selection_statement (cp_parser* parser, bool *if_p, pedwarn (cp_lexer_peek_token (parser->lexer)->location, 0, "init-statement in selection statements only available " "with %<-std=c++17%> or %<-std=gnu++17%>"); + if (cp_lexer_next_token_is_not (parser->lexer, CPP_SEMICOLON)) + { + /* A non-empty init-statement can have arbitrary side + effects. */ + delete chain; + chain = NULL; + } cp_parser_init_statement (parser, &decl); } diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 7f2d590..ddfdaa6 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-03-25 Patrick Palka <ppalka@redhat.com> + + PR c++/94265 + * g++.dg/warn/Wduplicated-cond1.C: New test. + 2020-03-25 Martin Sebor <msebor@redhat.com> PR tree-optimization/94131 diff --git a/gcc/testsuite/g++.dg/warn/Wduplicated-cond1.C b/gcc/testsuite/g++.dg/warn/Wduplicated-cond1.C new file mode 100644 index 0000000..e85920a --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wduplicated-cond1.C @@ -0,0 +1,16 @@ +// PR c++/94265 +// { dg-do compile { target c++17 } } +// { dg-additional-options "-Wduplicated-cond" } + +void +foo () +{ + if (int a = 0; a) + { } + else if (a = 5; a) // { dg-message "previously used here" } + { } + else if (; a) // { dg-warning "duplicated .if. condition" } + { } + else if (int b = ++a; a) + { } +} |