[PATCH] a68: Fix ICE in a68_extract_indicants

[Iain Buclaw]

Hi,

I stumbled across a segfault in the algol68 compiler when it encounters
an invalid module syntax.

After seeing a `module' symbol token, the parser skips over the contents
of the module until it finds the terminating `fed' symbol token, then
moves forward to the next token to scan.  If instead the parser reaches
the end of file, then skip_module_text returns NULL, triggering an ICE
in the call to FORWARD.

Ran the compiler testsuite and didn't observe any regressions.

OK?

Regards,
Iain.

---
gcc/algol68/ChangeLog:

        * a68-parser-extract.cc (a68_extract_indicants): Don't call FORWARD if
        skip_module_text returns NO_NODE.

gcc/testsuite/ChangeLog:

        * algol68/compile/error-module-definition-1.a68: New test.
        * algol68/compile/error-module-definition-2.a68: New test.
---
 gcc/algol68/a68-parser-extract.cc                           | 4 ++--
 gcc/testsuite/algol68/compile/error-module-definition-1.a68 | 1 +
 gcc/testsuite/algol68/compile/error-module-definition-2.a68 | 3 +++
 3 files changed, 6 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/algol68/compile/error-module-definition-1.a68
 create mode 100644 gcc/testsuite/algol68/compile/error-module-definition-2.a68

diff --git a/gcc/algol68/a68-parser-extract.cc 
b/gcc/algol68/a68-parser-extract.cc
index 32a9933bd72..92a1e676012 100644
--- a/gcc/algol68/a68-parser-extract.cc
+++ b/gcc/algol68/a68-parser-extract.cc
@@ -415,8 +415,8 @@ a68_extract_indicants (NODE_T *p)
                    }
                  else
                    {
-                     q = skip_module_text (NEXT (q));
-                     FORWARD (q);
+                     if ((q = skip_module_text (NEXT (q))) != NO_NODE)
+                       FORWARD (q);
                    }
                }
              else
diff --git a/gcc/testsuite/algol68/compile/error-module-definition-1.a68 
b/gcc/testsuite/algol68/compile/error-module-definition-1.a68
new file mode 100644
index 00000000000..bc763bd682b
--- /dev/null
+++ b/gcc/testsuite/algol68/compile/error-module-definition-1.a68
@@ -0,0 +1 @@
+module Module = { dg-error "" }
diff --git a/gcc/testsuite/algol68/compile/error-module-definition-2.a68 
b/gcc/testsuite/algol68/compile/error-module-definition-2.a68
new file mode 100644
index 00000000000..d2ad87b5d6c
--- /dev/null
+++ b/gcc/testsuite/algol68/compile/error-module-definition-2.a68
@@ -0,0 +1,3 @@
+module Module = { dg-error "" }
+begin
+end
-- 
2.43.0