https://gcc.gnu.org/g:5943a2fa1bc5407332a91976c145446cdb8ded7b
commit r15-4010-g5943a2fa1bc5407332a91976c145446cdb8ded7b
Author: Jakub Jelinek <ja...@redhat.com>
Date: Wed Oct 2 10:53:35 2024 +0200
libcpp: Implement clang -Wheader-guard warning [PR96842]
The following patch implements the clang -Wheader-guard warning, which warns
if a valid multiple inclusion header guard's #ifndef/#if !defined directive
is immediately (no other non-line directives nor other (non-comment)
tokens in between) followed by #define directive for some different macro,
which in get_suggestion rules is close enough to the actual header guard
macro (i.e. likely misspelling), the #define is object-like with empty
definition (I've followed what clang implements) and the macro isn't defined
later on (at least not on the final #endif at the end of a header).
In this case it emits a warning, so that
#ifndef STDIO_H
#define STDOI_H
...
#endif
or similar misspellings can be caught.
clang enables this warning by default, but I've put it into -Wall instead
as it still seems to be a style warning, nothing more severe; if a header
doesn't survive multiple inclusion because of the misspelling, users will
get different diagnostics.
2024-10-02 Jakub Jelinek <ja...@redhat.com>
PR preprocessor/96842
libcpp/
* include/cpplib.h (struct cpp_options): Add warn_header_guard
member.
(enum cpp_warning_reason): Add CPP_W_HEADER_GUARD enumerator.
* internal.h (struct cpp_reader): Add mi_def_cmacro, mi_loc and
mi_def_loc members.
(_cpp_defined_macro_p): Constify type pointed by argument type.
Formatting fix.
* init.cc (cpp_create_reader): Clear
CPP_OPTION (pfile, warn_header_guard).
* directives.cc (struct if_stack): Add def_loc and mi_def_cmacro
members.
(DIRECTIVE_TABLE): Add IF_COND flag to define.
(do_define): Set ifs->mi_def_cmacro on a define immediately
following
#ifndef directive for the guard. Clear pfile->mi_valid. Formatting
fix.
(do_endif): Copy over pfile->mi_def_cmacro and pfile->mi_def_loc
if ifs->mi_def_cmacro is set and pfile->mi_cmacro isn't a defined
macro.
(push_conditional): Clear mi_def_cmacro and mi_def_loc members.
* files.cc (_cpp_pop_file_buffer): Emit -Wheader-guard diagnostics.
gcc/
* doc/invoke.texi (Wheader-guard): Document.
gcc/c-family/
* c.opt (Wheader-guard): New option.
* c.opt.urls: Regenerated.
* c-ppoutput.cc (init_pp_output): Initialize also
cb->get_suggestion.
gcc/testsuite/
* c-c++-common/cpp/Wheader-guard-1.c: New test.
* c-c++-common/cpp/Wheader-guard-1-1.h: New test.
* c-c++-common/cpp/Wheader-guard-1-2.h: New test.
* c-c++-common/cpp/Wheader-guard-1-3.h: New test.
* c-c++-common/cpp/Wheader-guard-1-4.h: New test.
* c-c++-common/cpp/Wheader-guard-1-5.h: New test.
* c-c++-common/cpp/Wheader-guard-1-6.h: New test.
* c-c++-common/cpp/Wheader-guard-1-7.h: New test.
* c-c++-common/cpp/Wheader-guard-1-8.h: New test.
* c-c++-common/cpp/Wheader-guard-1-9.h: New test.
* c-c++-common/cpp/Wheader-guard-1-10.h: New test.
* c-c++-common/cpp/Wheader-guard-1-11.h: New test.
* c-c++-common/cpp/Wheader-guard-1-12.h: New test.
* c-c++-common/cpp/Wheader-guard-2.c: New test.
* c-c++-common/cpp/Wheader-guard-2.h: New test.
* c-c++-common/cpp/Wheader-guard-3.c: New test.
* c-c++-common/cpp/Wheader-guard-3.h: New test.
Diff:
---
gcc/c-family/c-ppoutput.cc | 1 +
gcc/c-family/c.opt | 4 +++
gcc/c-family/c.opt.urls | 3 ++
gcc/doc/invoke.texi | 15 +++++++-
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-1.h | 5 +++
.../c-c++-common/cpp/Wheader-guard-1-10.h | 5 +++
.../c-c++-common/cpp/Wheader-guard-1-11.h | 5 +++
.../c-c++-common/cpp/Wheader-guard-1-12.h | 5 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-2.h | 4 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-3.h | 4 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-4.h | 3 ++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-5.h | 5 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-6.h | 8 +++++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-7.h | 4 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-8.h | 5 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-9.h | 5 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-1.c | 19 ++++++++++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.c | 10 ++++++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.h | 4 +++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.c | 10 ++++++
gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.h | 4 +++
libcpp/directives.cc | 42 +++++++++++++++++++---
libcpp/files.cc | 21 ++++++++++-
libcpp/include/cpplib.h | 7 +++-
libcpp/init.cc | 1 +
libcpp/internal.h | 7 ++--
26 files changed, 197 insertions(+), 9 deletions(-)
diff --git a/gcc/c-family/c-ppoutput.cc b/gcc/c-family/c-ppoutput.cc
index c674610760b6..e3f5ca3ec97c 100644
--- a/gcc/c-family/c-ppoutput.cc
+++ b/gcc/c-family/c-ppoutput.cc
@@ -164,6 +164,7 @@ init_pp_output (FILE *out_stream)
cb->has_builtin = c_common_has_builtin;
cb->has_feature = c_common_has_feature;
cb->get_source_date_epoch = cb_get_source_date_epoch;
+ cb->get_suggestion = cb_get_suggestion;
cb->remap_filename = remap_macro_filename;
/* Initialize the print structure. */
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index b5983093e24a..77fe1b02bd2f 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -828,6 +828,10 @@ Wglobal-module
C++ ObjC++ Var(warn_global_module) Warning Init(1)
Warn about the global module fragment not containing only preprocessing
directives.
+Wheader-guard
+C ObjC C++ ObjC++ CPP(warn_header_guard) CppReason(CPP_W_HEADER_GUARD)
Var(cpp_warn_header_guard) Init(0) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
+Warn when #ifndef of a header guard is followed by #define of a different
macro with the header guard macro not defined at the end of header.
+
Wif-not-aligned
C ObjC C++ ObjC++ Var(warn_if_not_aligned) Init(1) Warning
Warn when the field in a struct is not aligned.
diff --git a/gcc/c-family/c.opt.urls b/gcc/c-family/c.opt.urls
index 47a54926363b..4cd9a75b950c 100644
--- a/gcc/c-family/c.opt.urls
+++ b/gcc/c-family/c.opt.urls
@@ -415,6 +415,9 @@ UrlSuffix(gcc/Warning-Options.html#index-Wframe-address)
Wglobal-module
UrlSuffix(gcc/C_002b_002b-Dialect-Options.html#index-Wglobal-module)
+Wheader-guard
+UrlSuffix(gcc/Warning-Options.html#index-Wheader-guard)
+
Wif-not-aligned
UrlSuffix(gcc/Warning-Options.html#index-Wif-not-aligned)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index bd1208a62ee1..e199522f62c7 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -372,7 +372,7 @@ Objective-C and Objective-C++ Dialects}.
-Wformat-security -Wformat-signedness -Wformat-truncation=@var{n}
-Wformat-y2k -Wframe-address
-Wframe-larger-than=@var{byte-size} -Wno-free-nonheap-object
--Wno-if-not-aligned -Wno-ignored-attributes
+-Wheader-guard -Wno-if-not-aligned -Wno-ignored-attributes
-Wignored-qualifiers -Wno-incompatible-pointer-types -Whardened
-Wimplicit -Wimplicit-fallthrough -Wimplicit-fallthrough=@var{n}
-Wno-implicit-function-declaration -Wno-implicit-int
@@ -10115,6 +10115,19 @@ Do not warn if certain built-in macros are redefined.
This suppresses
warnings for redefinition of @code{__TIMESTAMP__}, @code{__TIME__},
@code{__DATE__}, @code{__FILE__}, and @code{__BASE_FILE__}.
+@opindex Wheader-guard
+@item -Wheader-guard
+Warn if a valid preprocessor header multiple inclusion guard has
+a @code{#define} directive right after @code{#ifndef} or @code{#if !defined}
+directive for the multiple inclusion guard, which defines a different macro
+from the guard macro with a similar name, the actual multiple inclusion guard
+macro isn't defined at the corresponding @code{#ifndef} directive at the end
+of the header, and the @code{#define} directive defines an object-like macro
+with empty definition. In such case, it often is just a misspelled guard
+name, either in the @code{#ifndef} or @code{#if !defined} directive or in the
+subsequent @code{#define} directive. This warning is enabled
+by @option{-Wall}.
+
@opindex Wstrict-prototypes
@opindex Wno-strict-prototypes
@item -Wstrict-prototypes @r{(C and Objective-C only)}
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-1.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-1.h
new file mode 100644
index 000000000000..1ac3fe865ad4
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-1.h
@@ -0,0 +1,5 @@
+#ifndef WHEADER_GUARD_1
+#define WHEADER_GUARD_1
+/* This is what header guards should look like. */
+#define SOMETHING1 123
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-10.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-10.h
new file mode 100644
index 000000000000..119a2a869b64
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-10.h
@@ -0,0 +1,5 @@
+#ifndef WHEADER_GUARD_10
+#define WHEADERGUARD10
+/* Don't warn if it actually isn't a valid header guard. */
+#else
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-11.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-11.h
new file mode 100644
index 000000000000..88820a51590f
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-11.h
@@ -0,0 +1,5 @@
+#ifndef WHEADER_GUARD_11
+#define WHEADERGUARD11
+/* Don't warn if it actually isn't a valid header guard. */
+#elif 1
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-12.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-12.h
new file mode 100644
index 000000000000..9233fbffea40
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-12.h
@@ -0,0 +1,5 @@
+#ifndef WHEADER_GUARD_12
+#define WHEADERGUARD12
+/* Don't warn if it actually isn't a valid header guard. */
+#endif
+#define ASOMETHING12
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-2.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-2.h
new file mode 100644
index 000000000000..25d4fb5b2e3f
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-2.h
@@ -0,0 +1,4 @@
+#ifndef WHEADER_GUARD_2
+#define WHEADERGUARD2 1
+/* Don't warn if the different macro defines some tokens. */
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-3.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-3.h
new file mode 100644
index 000000000000..d995e3f2cd4b
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-3.h
@@ -0,0 +1,4 @@
+#ifndef WHEADER_GUARD_3
+#define WHEADERGUARD3()
+/* Won't warn if it is a function-like macro. */
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-4.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-4.h
new file mode 100644
index 000000000000..6d031a5687a7
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-4.h
@@ -0,0 +1,3 @@
+#ifndef WHEADER_GUARD_4
+/* Don't warn if there is no define after #ifndef. */
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-5.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-5.h
new file mode 100644
index 000000000000..d691ba9f4f3f
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-5.h
@@ -0,0 +1,5 @@
+#ifndef WHEADER_GUARD_5
+int guard5;
+#define WHEADERGUARD5
+/* Don't warn if there are tokens in between #ifndef and #define. */
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-6.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-6.h
new file mode 100644
index 000000000000..1057162da387
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-6.h
@@ -0,0 +1,8 @@
+#ifndef WHEADER_GUARD_6
+#define WHEADERGUARD6
+/* Don't warn if WHEADER_GUARD_6 is eventually defined later. */
+#if 0
+#else
+#define WHEADER_GUARD_6
+#endif
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-7.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-7.h
new file mode 100644
index 000000000000..d0e0708ab662
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-7.h
@@ -0,0 +1,4 @@
+#ifndef WHEADER_GUARD_7
+#define SOMETHING7
+/* Don't warn if the two macros don't have similar names. */
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-8.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-8.h
new file mode 100644
index 000000000000..2be231bc1078
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-8.h
@@ -0,0 +1,5 @@
+#ifndef WHEADER_GUARD_8
+#define WHEADERGUARD8
+/* Don't warn if the guard macro is already defined before
+ including the header. */
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-9.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-9.h
new file mode 100644
index 000000000000..2152eafc89ce
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1-9.h
@@ -0,0 +1,5 @@
+int guard9;
+#ifndef WHEADER_GUARD_9
+#define WHEADERGUARD9
+/* Don't warn if it actually isn't a valid header guard. */
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1.c
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1.c
new file mode 100644
index 000000000000..6074d872afd5
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-1.c
@@ -0,0 +1,19 @@
+/* PR preprocessor/96842 */
+/* { dg-do preprocess } */
+/* { dg-options "-Wall" } */
+
+#include "Wheader-guard-1-1.h"
+#include "Wheader-guard-1-2.h"
+#include "Wheader-guard-1-3.h"
+#include "Wheader-guard-1-4.h"
+#include "Wheader-guard-1-5.h"
+#include "Wheader-guard-1-6.h"
+#include "Wheader-guard-1-7.h"
+#define WHEADER_GUARD_8
+#include "Wheader-guard-1-8.h"
+#include "Wheader-guard-1-9.h"
+#include "Wheader-guard-1-10.h"
+#include "Wheader-guard-1-11.h"
+#include "Wheader-guard-1-12.h"
+
+int i;
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.c
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.c
new file mode 100644
index 000000000000..9596fe7e3a09
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.c
@@ -0,0 +1,10 @@
+/* PR preprocessor/96842 */
+/* { dg-do preprocess } */
+/* { dg-options "-Wheader-guard" } */
+
+#include "Wheader-guard-2.h"
+
+int i;
+
+/* { dg-warning "header guard \"WHEADER_GUARD_2\" followed by \"#define\" of a
different macro" "" { target *-*-* } 0 } */
+/* { dg-message "\"WHEADERGUARD2\" is defined here; did you mean
\"WHEADER_GUARD_2\"\\\?" "" { target *-*-* } 0 } */
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.h
new file mode 100644
index 000000000000..c38d2d52b599
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-2.h
@@ -0,0 +1,4 @@
+#ifndef WHEADER_GUARD_2
+#define WHEADERGUARD2
+#define SOMETHING2 123
+#endif
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.c
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.c
new file mode 100644
index 000000000000..9fa4fbfa3076
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.c
@@ -0,0 +1,10 @@
+/* PR preprocessor/96842 */
+/* { dg-do preprocess } */
+/* { dg-options "-Wall" } */
+
+#include "Wheader-guard-3.h"
+
+int i;
+
+/* { dg-warning "header guard \"WHEADER_GUARD_3\" followed by \"#define\" of a
different macro" "" { target *-*-* } 0 } */
+/* { dg-message "\"WHEADERGUARD3\" is defined here; did you mean
\"WHEADER_GUARD_3\"\\\?" "" { target *-*-* } 0 } */
diff --git a/gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.h
b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.h
new file mode 100644
index 000000000000..cb610ed47223
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Wheader-guard-3.h
@@ -0,0 +1,4 @@
+#if !defined(WHEADER_GUARD_3)
+#define WHEADERGUARD3
+#define SOMETHING3 123
+#endif
diff --git a/libcpp/directives.cc b/libcpp/directives.cc
index 866ac9a823d0..c30087c7a1d9 100644
--- a/libcpp/directives.cc
+++ b/libcpp/directives.cc
@@ -31,7 +31,11 @@ struct if_stack
{
struct if_stack *next;
location_t line; /* Line where condition started. */
- const cpp_hashnode *mi_cmacro;/* macro name for #ifndef around entire file */
+ location_t def_loc; /* Locus of the following #define if any. */
+ const cpp_hashnode *mi_cmacro;/* Macro name for #ifndef around entire
+ file. */
+ const cpp_hashnode *mi_def_cmacro; /* Macro name in the following
+ #define. */
bool skip_elses; /* Can future #else / #elif be skipped? */
bool was_skipping; /* If were skipping on entry. */
int type; /* Most recent conditional for diagnostics. */
@@ -144,7 +148,7 @@ static void cpp_pop_definition (cpp_reader *, struct
def_pragma_macro *);
where the extension appears to have come from. */
#define DIRECTIVE_TABLE
\
- D(define, T_DEFINE = 0, KANDR, IN_I) \
+ D(define, T_DEFINE = 0, KANDR, IN_I | IF_COND) \
D(include, T_INCLUDE, KANDR, INCL | EXPAND) \
D(endif, T_ENDIF, KANDR, COND) \
D(ifdef, T_IFDEF, KANDR, COND | IF_COND) \
@@ -680,8 +684,8 @@ do_define (cpp_reader *pfile)
/* If we have been requested to expand comments into macros,
then re-enable saving of comments. */
- pfile->state.save_comments =
- ! CPP_OPTION (pfile, discard_comments_in_macro_exp);
+ pfile->state.save_comments
+ = ! CPP_OPTION (pfile, discard_comments_in_macro_exp);
if (pfile->cb.before_define)
pfile->cb.before_define (pfile);
@@ -691,7 +695,28 @@ do_define (cpp_reader *pfile)
pfile->cb.define (pfile, pfile->directive_line, node);
node->flags &= ~NODE_USED;
+
+ if (pfile->mi_valid
+ && !pfile->mi_cmacro
+ && CPP_OPTION (pfile, warn_header_guard)
+ && node->type == NT_USER_MACRO
+ && node->value.macro
+ && node->value.macro->count == 0
+ && !node->value.macro->fun_like)
+ {
+ cpp_buffer *buffer = pfile->buffer;
+ struct if_stack *ifs = buffer->if_stack;
+ if (ifs
+ && !ifs->next
+ && ifs->mi_cmacro
+ && node != ifs->mi_cmacro)
+ {
+ ifs->mi_def_cmacro = node;
+ ifs->def_loc = pfile->directive_line;
+ }
+ }
}
+ pfile->mi_valid = false;
}
/* Handle #undef. Mark the identifier NT_VOID in the hash table. */
@@ -2711,6 +2736,13 @@ do_endif (cpp_reader *pfile)
{
pfile->mi_valid = true;
pfile->mi_cmacro = ifs->mi_cmacro;
+ pfile->mi_loc = ifs->line;
+ pfile->mi_def_cmacro = nullptr;
+ if (ifs->mi_def_cmacro && !_cpp_defined_macro_p (pfile->mi_cmacro))
+ {
+ pfile->mi_def_cmacro = ifs->mi_def_cmacro;
+ pfile->mi_def_loc = ifs->def_loc;
+ }
}
buffer->if_stack = ifs->next;
@@ -2732,6 +2764,7 @@ push_conditional (cpp_reader *pfile, int skip, int type,
ifs = XOBNEW (&pfile->buffer_ob, struct if_stack);
ifs->line = pfile->directive_line;
+ ifs->def_loc = 0;
ifs->next = buffer->if_stack;
ifs->skip_elses = pfile->state.skipping || !skip;
ifs->was_skipping = pfile->state.skipping;
@@ -2741,6 +2774,7 @@ push_conditional (cpp_reader *pfile, int skip, int type,
ifs->mi_cmacro = cmacro;
else
ifs->mi_cmacro = 0;
+ ifs->mi_def_cmacro = nullptr;
pfile->state.skipping = skip;
buffer->if_stack = ifs;
diff --git a/libcpp/files.cc b/libcpp/files.cc
index 031169978e72..5f9fbc54e999 100644
--- a/libcpp/files.cc
+++ b/libcpp/files.cc
@@ -2253,7 +2253,26 @@ _cpp_pop_file_buffer (cpp_reader *pfile, _cpp_file *file,
/* Record the inclusion-preventing macro, which could be NULL
meaning no controlling macro. */
if (pfile->mi_valid && file->cmacro == NULL)
- file->cmacro = pfile->mi_cmacro;
+ {
+ file->cmacro = pfile->mi_cmacro;
+ if (pfile->mi_cmacro
+ && pfile->mi_def_cmacro
+ && pfile->cb.get_suggestion)
+ {
+ auto mi_cmacro = (const char *) NODE_NAME (pfile->mi_cmacro);
+ auto mi_def_cmacro = (const char *) NODE_NAME (pfile->mi_def_cmacro);
+ const char *names[] = { mi_def_cmacro, NULL };
+ if (pfile->cb.get_suggestion (pfile, mi_cmacro, names)
+ && cpp_warning_with_line (pfile, CPP_W_HEADER_GUARD,
+ pfile->mi_loc, 0,
+ "header guard \"%s\" followed by "
+ "\"#define\" of a different macro",
+ mi_cmacro))
+ cpp_error_at (pfile, CPP_DL_NOTE, pfile->mi_def_loc,
+ "\"%s\" is defined here; did you mean \"%s\"?",
+ mi_def_cmacro, mi_cmacro);
+ }
+ }
/* Invalidate control macros in the #including file. */
pfile->mi_valid = false;
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 76e2437e06a1..fbddc34b6af0 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -435,6 +435,10 @@ struct cpp_options
/* Different -Wimplicit-fallthrough= levels. */
unsigned char cpp_warn_implicit_fallthrough;
+ /* Nonzero means warn about a define of a different macro right after
+ #ifndef/#if !defined header guard directive. */
+ unsigned char warn_header_guard;
+
/* Nonzero means we should look for header.gcc files that remap file
names. */
unsigned char remap;
@@ -709,7 +713,8 @@ enum cpp_warning_reason {
CPP_W_EXPANSION_TO_DEFINED,
CPP_W_BIDIRECTIONAL,
CPP_W_INVALID_UTF8,
- CPP_W_UNICODE
+ CPP_W_UNICODE,
+ CPP_W_HEADER_GUARD
};
/* Callback for header lookup for HEADER, which is the name of a
diff --git a/libcpp/init.cc b/libcpp/init.cc
index b22481c29653..2c80d63a491d 100644
--- a/libcpp/init.cc
+++ b/libcpp/init.cc
@@ -230,6 +230,7 @@ cpp_create_reader (enum c_lang lang, cpp_hash_table *table,
CPP_OPTION (pfile, warn_variadic_macros) = 1;
CPP_OPTION (pfile, warn_builtin_macro_redefined) = 1;
CPP_OPTION (pfile, cpp_warn_implicit_fallthrough) = 0;
+ CPP_OPTION (pfile, warn_header_guard) = 0;
/* By default, track locations of tokens resulting from macro
expansion. The '2' means, track the locations with the highest
accuracy. Read the comments for struct
diff --git a/libcpp/internal.h b/libcpp/internal.h
index fa64a69954ff..b69a0377f024 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -495,9 +495,11 @@ struct cpp_reader
been used. */
bool seen_once_only;
- /* Multiple include optimization. */
+ /* Multiple include optimization and -Wheader-guard warning. */
const cpp_hashnode *mi_cmacro;
const cpp_hashnode *mi_ind_cmacro;
+ const cpp_hashnode *mi_def_cmacro;
+ location_t mi_loc, mi_def_loc;
bool mi_valid;
/* Lexing. */
@@ -696,7 +698,8 @@ _cpp_in_main_source_file (cpp_reader *pfile)
}
/* True if NODE is a macro for the purposes of ifdef, defined etc. */
-inline bool _cpp_defined_macro_p (cpp_hashnode *node)
+inline bool
+_cpp_defined_macro_p (const cpp_hashnode *node)
{
/* Do not treat conditional macros as being defined. This is due to
the powerpc port using conditional macros for 'vector', 'bool',
