[gcc r12-948] PR middle-end/100684 - spurious -Wnonnull with -O1 on a C++ lambda

[gcc r12-948] PR middle-end/100684 - spurious -Wnonnull with -O1 on a C++ lambda

[Martin Sebor]

https://gcc.gnu.org/g:9480491a6447576e8e695b8ea3c4989cf72c9670

commit r12-948-g9480491a6447576e8e695b8ea3c4989cf72c9670
Author: Martin Sebor <msebor@redhat.com>
Date:   Thu May 20 13:15:58 2021 -0600

    PR middle-end/100684 - spurious -Wnonnull with -O1 on a C++ lambda
    
    gcc/ChangeLog:
    
            PR middle-end/100684
            * tree-ssa-ccp.c (pass_post_ipa_warn::execute): Handle C++ lambda.
    
    gcc/testsuite/ChangeLog:
    
            PR middle-end/100684
            * g++.dg/warn/Wnonnull13.C: New test.
            * g++.dg/warn/Wnonnull14.C: New test.
            * g++.dg/warn/Wnonnull15.C: New test.

Diff:
---
 gcc/testsuite/g++.dg/warn/Wnonnull13.C | 28 ++++++++++++++++++++++++++++
 gcc/testsuite/g++.dg/warn/Wnonnull14.C | 28 ++++++++++++++++++++++++++++
 gcc/testsuite/g++.dg/warn/Wnonnull15.C | 28 ++++++++++++++++++++++++++++
 gcc/tree-ssa-ccp.c                     |  4 ++++
 4 files changed, 88 insertions(+)

diff --git a/gcc/testsuite/g++.dg/warn/Wnonnull13.C b/gcc/testsuite/g++.dg/warn/Wnonnull13.C
new file mode 100644
index 00000000000..e3279764ac0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wnonnull13.C
@@ -0,0 +1,28 @@
+/* PR middle-end/100684 - spurious -Wnonnull with -O1 on a C++ lambda
+   { dg-do compile { target c++11 } }
+   { dg-options "-O0 -Wall -fsanitize=undefined" } */
+
+#define NONNULL  __attribute__ ((nonnull))
+
+typedef int F (const char *);
+
+NONNULL int f (const char *);
+
+int nowarn_O0 ()
+{
+  return static_cast<F*>([](const char *s){ return f (s); })("O0");
+  // { dg-bogus "\\\[-Wnonnull" "" { target *-*-* } .-1 }
+}
+
+int warn_O0 ()
+{
+  return static_cast<F*>([] NONNULL (const char *){ return 0; })(0);
+  // { dg-warning "\\\[-Wnonnull" "" { target *-*-* } .-1 }
+}
+
+int warn_O0_inline ()
+{
+  return static_cast<F*>([](const char *s){ return f (s); })(0);
+  // { dg-warning "\\\[-Wnonnull" "lambda not inlined" { xfail *-*-* } .-1 }
+}
+
diff --git a/gcc/testsuite/g++.dg/warn/Wnonnull14.C b/gcc/testsuite/g++.dg/warn/Wnonnull14.C
new file mode 100644
index 00000000000..16d7ec3f573
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wnonnull14.C
@@ -0,0 +1,28 @@
+/* PR middle-end/100684 - spurious -Wnonnull with -O1 on a C++ lambda
+   { dg-do compile { target c++11 } }
+   { dg-options "-Og -Wall -fsanitize=undefined" } */
+
+#define NONNULL  __attribute__ ((nonnull))
+
+typedef int F (const char *);
+
+__attribute__ ((nonnull)) int f (const char *);
+
+int nowarn_Og ()
+{
+  return static_cast<F*>([](const char *s){ return f (s); })("Og");
+  // { dg-bogus "'this' pointer is null" "" { target *-*-* } .-1 }
+}
+
+int warn_Og ()
+{
+  return static_cast<F*>([] NONNULL (const char *){ return 0; })(0);
+  // { dg-warning "\\\[-Wnonnull" "" { target *-*-* } .-1 }
+}
+
+int warn_Og_inline ()
+{
+  const char *p = 0;
+  return static_cast<F*>([](const char *s){ return f (s); })(p);
+  // { dg-warning "\\\[-Wnonnull" "lambda not inlined" { xfail *-*-* } .-1 }
+}
diff --git a/gcc/testsuite/g++.dg/warn/Wnonnull15.C b/gcc/testsuite/g++.dg/warn/Wnonnull15.C
new file mode 100644
index 00000000000..36a2ab48789
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wnonnull15.C
@@ -0,0 +1,28 @@
+/* PR middle-end/100684 - spurious -Wnonnull with -O1 on a C++ lambda
+   { dg-do compile { target c++11 } }
+   { dg-options "-O1 -Wall -fsanitize=undefined" } */
+
+#define NONNULL  __attribute__ ((nonnull))
+
+typedef int F (const char *);
+
+NONNULL int f (const char *);
+
+int nowarn_O1 ()
+{
+  return static_cast<F*>([](const char *s){ return f (s); })("O1");
+  // { dg-bogus "\\\[-Wnonnull" "" { target *-*-* } .-1 }
+}
+
+int warn_O1 ()
+{
+  return static_cast<F*>([] NONNULL (const char *){ return 0; })(0);
+  // { dg-warning "\\\[-Wnonnull" "" { target *-*-* } .-1 }
+}
+
+int warn_O1_inline ()
+{
+  const char *p = 0;
+  return static_cast<F*>([](const char *s){ return f (s); })(p);
+  // { dg-warning "\\\[-Wnonnull" "lambda not inlined" { xfail *-*-* } .-1 }
+}
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index bf31f035153..3834212b867 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -3536,6 +3536,7 @@ pass_post_ipa_warn::execute (function *fun)
 	    continue;
 
 	  tree fndecl = gimple_call_fndecl (stmt);
+	  const bool closure = fndecl && DECL_LAMBDA_FUNCTION_P (fndecl);
 
 	  for (unsigned i = 0; i < gimple_call_num_args (stmt); i++)
 	    {
@@ -3544,6 +3545,9 @@ pass_post_ipa_warn::execute (function *fun)
 		continue;
 	      if (!integer_zerop (arg))
 		continue;
+	      if (i == 0 && closure)
+		/* Avoid warning for the first argument to lambda functions.  */
+		continue;
 	      if (!bitmap_empty_p (nonnullargs)
 		  && !bitmap_bit_p (nonnullargs, i))
 		continue;