We warn about uses of uninitialized variables from the middle end, via
warn_uninit.
This patch adds the ability for such warnings to contain fix-it hints,
showing the user how to zero-initialize the relevant variables.
Naturally this is highly frontend-dependent, so the patch adds a langhook:
LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX to allow the frontend to optionally
provide a fragment of text to be inserted after the decl.
This is implemented for the C and C++ frontends, for a subset of types,
falling back to not emitting a hint if it's not clearly correct to do so.
The precise text varies with the type e.g. "0" vs "0.0f" vs "0.0" vs "false"
vs "NULL".
In combination with -fdiagnostics-generate-patch this can generate output
like this:
--- ../../src/gcc/testsuite/c-c++-common/fix-missing-initializer-1.c
+++ ../../src/gcc/testsuite/c-c++-common/fix-missing-initializer-1.c
@@ -2,7 +2,7 @@
int test_int (void)
{
- int ivar;
+ int ivar = 0;
return ivar; /* { dg-warning "used uninitialized" } */
/* { dg-begin-multiline-output "" }
return ivar;
@@ -17,7 +17,7 @@
char test_char (void)
{
- char cvar;
+ char cvar = 0;
return cvar; /* { dg-warning "used uninitialized" } */
/* { dg-begin-multiline-output "" }
return cvar;
@@ -32,7 +32,7 @@
float test_float (void)
{
- float fvar;
+ float fvar = 0.0f;
return fvar; /* { dg-warning "used uninitialized" } */
/* { dg-begin-multiline-output "" }
return fvar;
@@ -47,7 +47,7 @@
double test_double (void)
{
- double dvar;
+ double dvar = 0.0;
return dvar; /* { dg-warning "used uninitialized" } */
/* { dg-begin-multiline-output "" }
return dvar;
@@ -73,7 +73,7 @@
int test_multiple_on_one_line (void)
{
- int ivar_a, ivar_b;
+ int ivar_a = 0, ivar_b = 0;
int tot = 0;
tot += ivar_a; /* { dg-warning "used uninitialized" } */
/* { dg-begin-multiline-output "" }
Successfully bootstrapped®rtested on x86_64-pc-linux-gnu.
Adds 93 PASS results to g++.sum.
Adds 33 PASS results to gcc.sum, converting
gcc.dg/uninit-15.c (test for warnings, line 23)
from an XFAIL to a PASS, due to the fix-it hint being emitted for the:
int j;
decl, and thus forcing the "note: 'j' was declared here"
to be printed.
OK for trunk?
gcc/c-family/ChangeLog:
* c-common.c (c_common_get_uninitialized_decl_fix): New function.
* c-common.h (c_common_get_uninitialized_decl_fix): New decl.
gcc/c/ChangeLog:
* c-lang.c (LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX): Redefine as
c_common_get_uninitialized_decl_fix.
gcc/cp/ChangeLog:
* cp-lang.c (LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX): Redefine as
c_common_get_uninitialized_decl_fix.
gcc/ChangeLog:
* langhooks-def.h (lhd_get_uninitialized_decl_fix): New decl.
(LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX): Define.
(LANG_HOOKS_INITIALIZER): Add
LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX.
* langhooks.c (lhd_get_uninitialized_decl_fix): New function.
* langhooks.h (struct lang_hooks_for_decls): Add field
"get_uninitialized_decl_fix".
gcc/testsuite/ChangeLog:
* c-c++-common/fix-missing-initializer-1.c: New test case.
* c-c++-common/fix-missing-initializer-2.c: New test case.
* g++.dg/fix-missing-initializer-1.C: New test case.
* gcc.dg/diagnostic-tree-expr-ranges-2.c: Add fix-it hints to
expected output.
* gcc.dg/fix-missing-initializer-1.c: New test case.
* gcc.dg/uninit-15.c: Remove xfail from "int j;".
gcc/ChangeLog:
* tree-ssa-uninit.c (warn_uninit): When issuing note about
location of declaration, potentially provide a fix-it hint.
---
gcc/c-family/c-common.c | 53 +++++++++++
gcc/c-family/c-common.h | 2 +
gcc/c/c-lang.c | 3 +
gcc/cp/cp-lang.c | 3 +
gcc/langhooks-def.h | 3 +
gcc/langhooks.c | 9 ++
gcc/langhooks.h | 7 ++
.../c-c++-common/fix-missing-initializer-1.c | 101 +++++++++++++++++++++
.../c-c++-common/fix-missing-initializer-2.c | 36 ++++++++
gcc/testsuite/g++.dg/fix-missing-initializer-1.C | 18 ++++
.../gcc.dg/diagnostic-tree-expr-ranges-2.c | 10 ++
gcc/testsuite/gcc.dg/fix-missing-initializer-1.c | 18 ++++
gcc/testsuite/gcc.dg/uninit-15.c | 2 +-
gcc/tree-ssa-uninit.c | 13 ++-
14 files changed, 275 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/fix-missing-initializer-1.c
create mode 100644 gcc/testsuite/c-c++-common/fix-missing-initializer-2.c
create mode 100644 gcc/testsuite/g++.dg/fix-missing-initializer-1.C
create mode 100644 gcc/testsuite/gcc.dg/fix-missing-initializer-1.c
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 328e5f6..f6325311 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -13060,4 +13060,57 @@ diagnose_mismatched_attributes (tree olddecl, tree
newdecl)
return warned;
}
+/* Implementation of LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX.
+ Given an uninitialized warning about a usage of DECL, return
+ a fragment of code suitable for insertion immediately after
+ DECL for initializing it, for use as a fix-it hint to
+ suppress the warning.
+ Return NULL if it's not possible to emit such a hint. */
+
+const char *
+c_common_get_uninitialized_decl_fix (const_tree decl)
+{
+ gcc_assert (decl);
+ tree type = TREE_TYPE (decl);
+ switch (TREE_CODE (type))
+ {
+ case INTEGER_TYPE:
+ return " = 0";
+
+ case REAL_TYPE:
+ {
+ if (type == float_type_node)
+ return " = 0.0f";
+ else if (type == double_type_node)
+ return " = 0.0";
+ else
+ return NULL;
+ }
+
+ case POINTER_TYPE:
+ {
+ tree pointed_to = TREE_TYPE (type);
+ if (TREE_CODE (pointed_to) == FUNCTION_TYPE)
+ /* We can't easily insert a fixit for a function pointer,
+ unless it's a typedef. For now don't attempt to. */
+ return NULL;
+
+ /* If the macro "NULL" has been defined, then suggest it. */
+ if (cpp_defined (parse_in, (const unsigned char *)"NULL", 4))
+ return " = NULL";
+ else
+ return NULL;
+ }
+
+ case BOOLEAN_TYPE:
+ /* If we have a BOOLEAN_TYPE, then presumably we have either
+ C++, or C99 onwards. */
+ return " = false";
+
+ default:
+ return NULL;
+ }
+}
+
+
#include "gt-c-family-c-common.h"
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 42ce969..a3c6f54 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1162,6 +1162,8 @@ class substring_loc
int m_end_idx;
};
+extern const char *c_common_get_uninitialized_decl_fix (const_tree);
+
/* In c-gimplify.c */
extern void c_genericize (tree);
extern int c_gimplify_expr (tree *, gimple_seq *, gimple_seq *);
diff --git a/gcc/c/c-lang.c b/gcc/c/c-lang.c
index b26be6a..866d351 100644
--- a/gcc/c/c-lang.c
+++ b/gcc/c/c-lang.c
@@ -37,6 +37,9 @@ enum c_language_kind c_language = clk_c;
#define LANG_HOOKS_INIT c_objc_common_init
#undef LANG_HOOKS_INIT_TS
#define LANG_HOOKS_INIT_TS c_common_init_ts
+#undef LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX
+#define LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX \
+ c_common_get_uninitialized_decl_fix
#if CHECKING_P
#undef LANG_HOOKS_RUN_LANG_SELFTESTS
diff --git a/gcc/cp/cp-lang.c b/gcc/cp/cp-lang.c
index 8cfee4f..75bab92 100644
--- a/gcc/cp/cp-lang.c
+++ b/gcc/cp/cp-lang.c
@@ -78,6 +78,9 @@ static tree cxx_enum_underlying_base_type (const_tree);
#define LANG_HOOKS_EH_RUNTIME_TYPE build_eh_type_type
#undef LANG_HOOKS_ENUM_UNDERLYING_BASE_TYPE
#define LANG_HOOKS_ENUM_UNDERLYING_BASE_TYPE cxx_enum_underlying_base_type
+#undef LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX
+#define LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX \
+ c_common_get_uninitialized_decl_fix
/* Each front end provides its own lang hook initializer. */
struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
diff --git a/gcc/langhooks-def.h b/gcc/langhooks-def.h
index 10d910c..962a708 100644
--- a/gcc/langhooks-def.h
+++ b/gcc/langhooks-def.h
@@ -56,6 +56,7 @@ extern void lhd_incomplete_type_error (location_t,
const_tree, const_tree);
extern tree lhd_type_promotes_to (tree);
extern void lhd_register_builtin_type (tree, const char *);
extern bool lhd_decl_ok_for_sibcall (const_tree);
+extern const char *lhd_get_uninitialized_decl_fix (const_tree);
extern size_t lhd_tree_size (enum tree_code);
extern HOST_WIDE_INT lhd_to_target_charset (HOST_WIDE_INT);
extern tree lhd_expr_to_decl (tree, bool *, bool *);
@@ -215,6 +216,7 @@ extern tree lhd_make_node (enum tree_code);
#define LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL lhd_warn_unused_global_decl
#define LANG_HOOKS_POST_COMPILATION_PARSING_CLEANUPS NULL
#define LANG_HOOKS_DECL_OK_FOR_SIBCALL lhd_decl_ok_for_sibcall
+#define LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX lhd_get_uninitialized_decl_fix
#define LANG_HOOKS_OMP_PRIVATIZE_BY_REFERENCE hook_bool_const_tree_false
#define LANG_HOOKS_OMP_PREDETERMINED_SHARING lhd_omp_predetermined_sharing
#define LANG_HOOKS_OMP_REPORT_DECL lhd_pass_through_t
@@ -241,6 +243,7 @@ extern tree lhd_make_node (enum tree_code);
LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL, \
LANG_HOOKS_POST_COMPILATION_PARSING_CLEANUPS, \
LANG_HOOKS_DECL_OK_FOR_SIBCALL, \
+ LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX, \
LANG_HOOKS_OMP_PRIVATIZE_BY_REFERENCE, \
LANG_HOOKS_OMP_PREDETERMINED_SHARING, \
LANG_HOOKS_OMP_REPORT_DECL, \
diff --git a/gcc/langhooks.c b/gcc/langhooks.c
index 3256a9d..667e39e 100644
--- a/gcc/langhooks.c
+++ b/gcc/langhooks.c
@@ -291,6 +291,15 @@ lhd_decl_ok_for_sibcall (const_tree decl ATTRIBUTE_UNUSED)
return true;
}
+/* Default implementation of LANG_HOOKS_GET_UNINITIALIZED_DECL_FIX.
+ Return NULL, meaning to not issue a fix-it hint. */
+
+const char *
+lhd_get_uninitialized_decl_fix (const_tree decl ATTRIBUTE_UNUSED)
+{
+ return NULL;
+}
+
/* Generic global declaration processing. This is meant to be called
by the front-ends at the end of parsing. C/C++ do their own thing,
but other front-ends may call this. */
diff --git a/gcc/langhooks.h b/gcc/langhooks.h
index 44c258e..521e984 100644
--- a/gcc/langhooks.h
+++ b/gcc/langhooks.h
@@ -215,6 +215,13 @@ struct lang_hooks_for_decls
/* True if this decl may be called via a sibcall. */
bool (*ok_for_sibcall) (const_tree);
+ /* Given an uninitialized warning about a usage of DECL, return
+ a fragment of code suitable for insertion immediately after
+ DECL for initializing it, for use as a fix-it hint to
+ suppress the warning, such as " = 0".
+ Return NULL if it's not possible to emit such a hint. */
+ const char * (*get_uninitialized_decl_fix) (const_tree);
+
/* True if OpenMP should privatize what this DECL points to rather
than the DECL itself. */
bool (*omp_privatize_by_reference) (const_tree);
diff --git a/gcc/testsuite/c-c++-common/fix-missing-initializer-1.c
b/gcc/testsuite/c-c++-common/fix-missing-initializer-1.c
new file mode 100644
index 0000000..f035195
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/fix-missing-initializer-1.c
@@ -0,0 +1,101 @@
+/* { dg-options "-fdiagnostics-show-caret -Wuninitialized" } */
+
+int test_int (void)
+{
+ int ivar;
+ return ivar; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return ivar;
+ ^~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ int ivar;
+ ^~~~
+ = 0
+ { dg-end-multiline-output "" } */
+}
+
+char test_char (void)
+{
+ char cvar;
+ return cvar; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return cvar;
+ ^~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ char cvar;
+ ^~~~
+ = 0
+ { dg-end-multiline-output "" } */
+}
+
+float test_float (void)
+{
+ float fvar;
+ return fvar; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return fvar;
+ ^~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ float fvar;
+ ^~~~
+ = 0.0f
+ { dg-end-multiline-output "" } */
+}
+
+double test_double (void)
+{
+ double dvar;
+ return dvar; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return dvar;
+ ^~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ double dvar;
+ ^~~~
+ = 0.0
+ { dg-end-multiline-output "" } */
+}
+
+void *test_ptr (void)
+{
+ void *ptr;
+ return ptr; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return ptr;
+ ^~~
+ { dg-end-multiline-output "" } */
+ /* NULL is not defined in this file, so no fix-it hint for pointers. */
+}
+
+int test_multiple_on_one_line (void)
+{
+ int ivar_a, ivar_b;
+ int tot = 0;
+ tot += ivar_a; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ tot += ivar_a;
+ ~~~~^~~~~~~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ int ivar_a, ivar_b;
+ ^~~~~~
+ = 0
+ { dg-end-multiline-output "" } */
+
+ tot += ivar_b; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ tot += ivar_b;
+ ~~~~^~~~~~~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ int ivar_a, ivar_b;
+ ^~~~~~
+ = 0
+ { dg-end-multiline-output "" } */
+
+ return tot;
+}
diff --git a/gcc/testsuite/c-c++-common/fix-missing-initializer-2.c
b/gcc/testsuite/c-c++-common/fix-missing-initializer-2.c
new file mode 100644
index 0000000..5e16b98
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/fix-missing-initializer-2.c
@@ -0,0 +1,36 @@
+/* { dg-options "-fdiagnostics-show-caret -Wuninitialized" } */
+
+#define NULL ((void)0)
+
+/* NULL is defined in this file, so pointers should get fix-it hints. */
+
+void *test_ptr (void)
+{
+ void *ptr;
+ return ptr; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return ptr;
+ ^~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ void *ptr;
+ ^~~
+ = NULL
+ { dg-end-multiline-output "" } */
+}
+
+/* ...apart from function pointers. */
+
+typedef void (*fnptr_t) (void);
+
+fnptr_t test_fnptr (void)
+{
+ void (*fnptr) (void);
+ return fnptr; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return fnptr;
+ ^~~~~
+ { dg-end-multiline-output "" } */
+ /* We don't have enough location information, so we can't provide an
+ initializer for the function pointer. */
+}
diff --git a/gcc/testsuite/g++.dg/fix-missing-initializer-1.C
b/gcc/testsuite/g++.dg/fix-missing-initializer-1.C
new file mode 100644
index 0000000..46bc7fc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/fix-missing-initializer-1.C
@@ -0,0 +1,18 @@
+/* { dg-options "-fdiagnostics-show-caret -Wuninitialized" } */
+
+int test_bool (void)
+{
+ bool bvar;
+ return bvar; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return bvar;
+ ^~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ bool bvar;
+ ^~~~
+ = false
+ { dg-end-multiline-output "" } */
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/diagnostic-tree-expr-ranges-2.c
b/gcc/testsuite/gcc.dg/diagnostic-tree-expr-ranges-2.c
index 302e233..79233c3 100644
--- a/gcc/testsuite/gcc.dg/diagnostic-tree-expr-ranges-2.c
+++ b/gcc/testsuite/gcc.dg/diagnostic-tree-expr-ranges-2.c
@@ -9,6 +9,11 @@ int test_uninit_1 (void)
return result;
^~~~~~
{ dg-end-multiline-output "" } */
+/* { dg-begin-multiline-output "" }
+ int result;
+ ^~~~~~
+ = 0
+ { dg-end-multiline-output "" } */
}
int test_uninit_2 (void)
@@ -19,5 +24,10 @@ int test_uninit_2 (void)
result += 3;
~~~~~~~^~~~
{ dg-end-multiline-output "" } */
+/* { dg-begin-multiline-output "" }
+ int result;
+ ^~~~~~
+ = 0
+ { dg-end-multiline-output "" } */
return result;
}
diff --git a/gcc/testsuite/gcc.dg/fix-missing-initializer-1.c
b/gcc/testsuite/gcc.dg/fix-missing-initializer-1.c
new file mode 100644
index 0000000..a1cc04e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fix-missing-initializer-1.c
@@ -0,0 +1,18 @@
+/* { dg-options "-fdiagnostics-show-caret -Wuninitialized" } */
+
+int test_bool (void)
+{
+ _Bool bvar;
+ return bvar; /* { dg-warning "used uninitialized" } */
+ /* { dg-begin-multiline-output "" }
+ return bvar;
+ ^~~~
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ _Bool bvar;
+ ^~~~
+ = false
+ { dg-end-multiline-output "" } */
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/uninit-15.c b/gcc/testsuite/gcc.dg/uninit-15.c
index 20bea95..02165ce 100644
--- a/gcc/testsuite/gcc.dg/uninit-15.c
+++ b/gcc/testsuite/gcc.dg/uninit-15.c
@@ -20,7 +20,7 @@ void baz (void);
void
bar (void)
{
- int j; /* { dg-message "note: 'j' was declared here" "" { xfail *-*-* } } */
+ int j; /* { dg-message "note: 'j' was declared here" } */
for (; foo (j); ++j) /* { dg-warning "'j' is used uninitialized" } */
baz ();
}
diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c
index d5f0344..5725086 100644
--- a/gcc/tree-ssa-uninit.c
+++ b/gcc/tree-ssa-uninit.c
@@ -33,6 +33,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-ssa.h"
#include "params.h"
#include "tree-cfg.h"
+#include "langhooks.h"
/* This implements the pass that does predicate aware warning on uses of
possibly uninitialized variables. The pass first collects the set of
@@ -180,11 +181,19 @@ warn_uninit (enum opt_code wc, tree t, tree expr, tree
var,
if (location == DECL_SOURCE_LOCATION (var))
return;
+ const char *initializer_fix
+ = lang_hooks.decls.get_uninitialized_decl_fix (var);
if (xloc.file != floc.file
|| linemap_location_before_p (line_table, location, cfun_loc)
|| linemap_location_before_p (line_table, cfun->function_end_locus,
- location))
- inform (DECL_SOURCE_LOCATION (var), "%qD was declared here", var);
+ location)
+ || initializer_fix)
+ {
+ rich_location richloc (line_table, DECL_SOURCE_LOCATION (var));
+ if (initializer_fix)
+ richloc.add_fixit_insert_after (initializer_fix);
+ inform_at_rich_loc (&richloc, "%qD was declared here", var);
+ }
}
}
--
1.8.5.3
