Bugreport (+fix) for gcc-2.95.2 with -frepo

[Stefan Westerfeld <stefan at space dot twc dot de>]

   Hi!

I've got a bug report concerning template instantiation and -frepo. I
observed, that the following code

/*
 * This source doesn't compile with
 *  - gcc-2.95.2 + binutils-2.9.5.0.22
 *  - egcs-1.1.1 + binutils-2.9.1
 *
 * compiling started with
 *
 *  $ gcc -frepo -c repo-bug.cc
 *  $ gcc -o repo-bug repo-bug.o
 */
#include <vector>
#include <stack>
#include <string>

int main()
{
	// this fails under egcs-1.1.1
	vector<string> v;
	v.push_back(string("Hello World"));

	// this fails under gcc-2.95.2
	stack<int> is;
	is.push(4);

	return 0;
}

doesn't compile with gcc-2.95.2 + binutils-2.9.5.0.22. The reason for that
is that the linker emits error messages like:

file.o: In function `User<int>::User(int const &)':
file.o:  ... here comes the real error message, like undefined reference...

which causes tlink.c (in the collect phase) to consider the first line to
contain a symbol that needs to be tweaked (so it would tweak
`User<int>::User(int const &)', which is obviously not the template that
is causing the error). So it fails.

I assume that only nested templates will cause such errors.

/* Here is another, simpler example */

template<class T>
class Keep {
	T foo;
public:
	Keep(const T& t);
};

template<class T>
Keep<T>::Keep(const T& t)
{
	foo = t;
}

template<class T>
class User {
	Keep<T> *k1;
public:
	User(const T& t);
};

template<class T>
User<T>::User(const T& t)
{
	k1 = new Keep<T>(t);		// that would give the error message above
}

int main()
{
	User<int> k(2);
	return 0;
}

The fix I did was kind of a "hack", since it will ignore the lines ending
with a colon when analyzing linker output. This will ignore the
"In function..." lines, and only tweak symbols of lines containing real
errors. After applying that fix, my C++ project compiled fine with -frepo.

However, this of course depends on linker output, and may not help for
any linker.

   Cu... Stefan

Here's the diff:

--- tlink.c	Tue Oct 12 08:39:14 1999
+++ tlink.c.new	Fri Jan 21 18:27:33 2000
@@ -597,6 +597,19 @@
     }
 }
 
+static int
+ends_with_colon(p)
+    const char *p;
+{
+  int result = 0;
+  while(*p)
+    {
+      result = (*p == ':');
+      p++;
+    }
+  return result;
+}
+
 /* Step through the output of the linker, in the file named FNAME, and
    adjust the settings for each symbol encountered.  */
 
@@ -615,6 +628,15 @@
       
       while (*p && ISSPACE ((unsigned char)*p))
 	++p;
+
+      /*
+       * expect this to be a line like
+       *
+       * file.o: In function `User<int>::User(int const &)':
+       * which is not really talking about a symbol (but breaking everything)
+       */
+      if (ends_with_colon(p))
+	continue;
 
       if (! *p)
 	continue;