[PATCH 3/3] PR c/68473: sanitize source range-printing within certain macro expansions (v2)

[David Malcolm <dmalcolm@redhat.com>]

Changes in v2:
  - add two more testcases, based on additional reproducers
    reported (one to the PR, another to a dup); now adds 17 PASS
    results to gcc.sum.
  - update for delayed expansion of locations within rich_location
    and the terminology fixes from the other patches in this kit.

As before this patch fixes PR c/68473 by bulletproofing the new
diagnostic_show_locus implementation against ranges that finish before
they start (which can happen when using the C preprocessor), falling
back to simply printing a caret.

gcc/ChangeLog:
	PR c/68473
	* diagnostic-show-locus.c (layout::layout): Sanitize the
	layout against ranges that finish before they start.

gcc/testsuite/ChangeLog:
	PR c/68473
	* gcc.dg/plugin/diagnostic-test-expressions-1.c (fminl): New decl.
	(TEST_EQ): New macro.
	(test_macro): New function.
	* gcc.dg/pr68473-2.c: New test case.
	* gcc.dg/pr68473-3.c: New test case.
	* gcc.target/i386/pr68473-1.c: New test case.
---
 gcc/diagnostic-show-locus.c                        | 24 +++++++++++++++-
 .../gcc.dg/plugin/diagnostic-test-expressions-1.c  | 17 +++++++++++
 gcc/testsuite/gcc.dg/pr68473-2.c                   | 23 +++++++++++++++
 gcc/testsuite/gcc.dg/pr68473-3.c                   | 33 ++++++++++++++++++++++
 gcc/testsuite/gcc.target/i386/pr68473-1.c          | 24 ++++++++++++++++
 5 files changed, 120 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr68473-2.c
 create mode 100644 gcc/testsuite/gcc.dg/pr68473-3.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr68473-1.c

diff --git a/gcc/diagnostic-show-locus.c b/gcc/diagnostic-show-locus.c
index f279019..0bcd333 100644
--- a/gcc/diagnostic-show-locus.c
+++ b/gcc/diagnostic-show-locus.c
@@ -473,9 +473,31 @@ layout::layout (diagnostic_context * context,
 	if (caret.file != m_exploc.file)
 	  continue;
 
+      /* Everything is now known to be in the correct source file,
+	 but it may require further sanitization.  */
+      layout_range ri (&start, &finish, nested_loc->m_show_caret_p, &caret);
+
+      /* If we have a range that finishes before it starts (perhaps
+	 from something built via macro expansion), printing the
+	 range is likely to be nonsensical.  Also, attempting to do so
+	 breaks assumptions within the printing code  (PR c/68473).  */
+      if (ri.m_start.m_line > ri.m_finish.m_line)
+	{
+	  /* Is this the primary location?  */
+	  if (m_layout_ranges.length () == 0)
+	    {
+	      /* We want to print the caret for the primary location, but
+		 we must sanitize away m_start and m_finish.  */
+	      ri.m_start = ri.m_caret;
+	      ri.m_finish = ri.m_caret;
+	    }
+	  else
+	    /* This is a non-primary location; ignore it.  */
+	    continue;
+	}
+
       /* Passed all the tests; add the location to m_layout_ranges so that
 	 it will be printed.  */
-      layout_range ri (&start, &finish, nested_loc->m_show_caret_p, &caret);
       m_layout_ranges.safe_push (ri);
 
       /* Update m_first_line/m_last_line if necessary.  */
diff --git a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-expressions-1.c b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-expressions-1.c
index 175b2ea..97426f6 100644
--- a/gcc/testsuite/gcc.dg/plugin/diagnostic-test-expressions-1.c
+++ b/gcc/testsuite/gcc.dg/plugin/diagnostic-test-expressions-1.c
@@ -618,3 +618,20 @@ void test_quadratic (double a, double b, double c)
    { dg-end-multiline-output "" } */
 
 }
+
+/* Reproducer for PR c/68473.  */
+
+extern long double fminl (long double __x, long double __y);
+#define TEST_EQ(FUNC) FUNC##l(xl,xl)
+void test_macro (long double xl)
+{
+  __emit_expression_range (0, TEST_EQ (fmin) ); /* { dg-warning "range" } */
+/* { dg-begin-multiline-output "" }
+   __emit_expression_range (0, TEST_EQ (fmin) );
+                                        ^
+   { dg-end-multiline-output "" } */
+/* { dg-begin-multiline-output "" }
+ #define TEST_EQ(FUNC) FUNC##l(xl,xl)
+                       ^~~~
+   { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/gcc.dg/pr68473-2.c b/gcc/testsuite/gcc.dg/pr68473-2.c
new file mode 100644
index 0000000..5a10f1c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr68473-2.c
@@ -0,0 +1,23 @@
+/* { dg-options "-fdiagnostics-show-caret -Wall" } */
+#define FOO(bar) bar && 42  /* { dg-warning "suggest parentheses" } */
+int param;
+int lhs;
+int f() { return lhs || FOO(param); }  /* { dg-message "in expansion of" } */
+
+/* { dg-begin-multiline-output "" }
+ #define FOO(bar) bar && 42
+                      ^
+   { dg-end-multiline-output "" } */
+
+/* { dg-begin-multiline-output "" }
+ int f() { return lhs || FOO(param); }
+                         ^~~
+   { dg-end-multiline-output "" } */
+
+/* TODO: ideally we'd print the full range of the expression as it
+   pertains to the primary caret:
+
+ #define FOO(bar) bar && 42
+                  ~~~~^~~~~
+
+*/
diff --git a/gcc/testsuite/gcc.dg/pr68473-3.c b/gcc/testsuite/gcc.dg/pr68473-3.c
new file mode 100644
index 0000000..d1f3107
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr68473-3.c
@@ -0,0 +1,33 @@
+/* From PR c/68839 (dup of 68473). */
+/* { dg-options "-fdiagnostics-show-caret -Wduplicated-cond" } */
+
+struct S { void *q; };
+
+#define NULL (void*)0
+
+void f (struct S *p)
+{
+  if (p->q != NULL) { } /* { dg-message "previously used here" } */
+    else if (p->q != NULL) { } /* { dg-warning "duplicated" } */
+}
+
+/* { dg-begin-multiline-output "" }
+     else if (p->q != NULL) { }
+                   ^
+   { dg-end-multiline-output "" } */
+
+/* { dg-begin-multiline-output "" }
+   if (p->q != NULL) { }
+            ^
+   { dg-end-multiline-output "" } */
+
+/* TODO: Ideally we'd print some form of the ranges as they pertain to the
+   primary caret within the location:
+
+     else if (p->q != NULL) { }
+              ~~~~~^~~~~~~
+
+     if (p->q != NULL) { }
+         ~~~~~^~~~~~~
+
+*/
diff --git a/gcc/testsuite/gcc.target/i386/pr68473-1.c b/gcc/testsuite/gcc.target/i386/pr68473-1.c
new file mode 100644
index 0000000..ffffaa7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68473-1.c
@@ -0,0 +1,24 @@
+/* { dg-options "-fdiagnostics-show-caret -mno-fp-ret-in-387" } */
+
+extern long double fminl (long double __x, long double __y);
+
+#define TEST_EQ(FUNC) do { \
+  if ((long)FUNC##l(xl,xl) != (long)xl) \
+    return; \
+  } while (0)
+
+void
+foo (long double xl)
+{
+  TEST_EQ (fmin); /* { dg-error "x87 register return with x87 disabled" } */
+}
+
+/* { dg-begin-multiline-output "" }
+   TEST_EQ (fmin);
+            ^
+   { dg-end-multiline-output "" } */
+
+/* { dg-begin-multiline-output "" }
+   if ((long)FUNC##l(xl,xl) != (long)xl) \
+             ^~~~
+   { dg-end-multiline-output "" } */
-- 
1.8.5.3